A time for retro-tech... the "Obi-Wan"

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  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15261

    A time for retro-tech... the "Obi-Wan"

    Hmm, I've heard a friend describe forums as "social media". And on "social media", teasers are common place, if not at times a majority of the posting!

    While I would not advocate that generally for HT Guide, sometimes it's hard to resist...


    Do you ever get tired of an unending procession of projects and posts all discussing the latest hideously expensive unobtanium drivers? I mean, a $1,645.00 11" woofer? Really? (guilty as charged)

    Perhaps it is time for a different approach... something that perhaps only an old retired geezer with 50+ years building speakers might come up with...


    If so, we may have something for you... soon. Imagine not a cheerfully youthful moniker, like the "Natalie P", but something representing the gravitas and weight of... decades.

    Imagine a driver set for which the "youngest" parts are about ten years old, and the oldest 30 years.

    Imagine a core driver set cost of about $100.

    Imagine an unconventional form factor, with detailed baffle analytics.

    Imagine solid performance to the low 30's at 100 dB.

    Imagine... the "Obi-Wan".



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    the AudioWorx
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    Resistance is not futile, it is Volts divided by Amperes...
    Just ask Mr. Ohm....
  • Chancellor
    Junior Member
    • Jan 2010
    • 12

    #2
    Events are proceeding as I have foreseen...


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    Comment

    • dwk
      Senior Member
      • Apr 2005
      • 251

      #3
      Well, this is intriguing. I'm sitting here trying to figure what 30 year old driver designs are still available, let alone ones that can find a home in a $100/side driver budget. (I'm assuming it's per side given what I think is a Dayton reference box there).

      Some of the classic scan-speak drivers like the 2905-9x00 tweeters and 85xx mid-woofers might date from that era, but they certainly aren't priced for this project. I'm guessing a Vifa or Seas tweeter, but so many have been discontinued that I don't have a lot of confidence in that guess.

      Side note - before we moved I was using a revived pair of Acuostic Reality pyramid speakers that used the classic scan-speak drivers (9500 or 9700 tweeter and carbon-pulp woofer). Made me really understand the attraction and nostalgia for them - wonderful rich, warm sound. No space for them in the new place, though.

      Anyway, watching with interest. I love these design threads.

      Comment

      • JonMarsh
        Mad Max Moderator
        • Aug 2000
        • 15261

        #4
        Originally posted by dwk
        Well, this is intriguing. I'm sitting here trying to figure what 30 year old driver designs are still available, let alone ones that can find a home in a $100/side driver budget. (I'm assuming it's per side given what I think is a Dayton reference box there).

        Anyway, watching with interest. I love these design threads.
        It's always about having fun! If we're not having fun, we're doing something wrong!

        This one may be a particular indulgence- going back to some old concepts and drivers with some new fangled design experience- hopefully with interesting results!
        the AudioWorx
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        In Development...
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        Resistance is not futile, it is Volts divided by Amperes...
        Just ask Mr. Ohm....

        Comment

        • technodanvan
          Senior Member
          • Nov 2009
          • 998

          #5
          That looks like a box of Anarchys to me. Can a box look like anything but a box?
          - Danny

          Comment

          • JonMarsh
            Mad Max Moderator
            • Aug 2000
            • 15261

            #6
            Well, it might LOOK like that, but PE doesn't sell Anarchy's, now do they?
            the AudioWorx
            Natalie P
            M8ta
            Modula Neo DCC
            Modula MT XE
            Modula Xtreme
            Isiris
            Wavecor Ardent

            SMJ
            Minerva Monitor
            Calliope
            Ardent D

            In Development...
            Isiris Mk II updates- in final test stage!
            Obi-Wan
            Saint-Saëns Symphonique/AKA SMJ-40
            Modula PWB
            Calliope CC Supreme
            Natalie P Ultra
            Natalie P Supreme
            Janus BP1 Sub


            Resistance is not futile, it is Volts divided by Amperes...
            Just ask Mr. Ohm....

            Comment

            • technodanvan
              Senior Member
              • Nov 2009
              • 998

              #7
              Hey, two of those boxes don't say Parts Express on them!
              - Danny

              Comment

              • JonMarsh
                Mad Max Moderator
                • Aug 2000
                • 15261

                #8
                Not that you can see....
                the AudioWorx
                Natalie P
                M8ta
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                Modula Xtreme
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                SMJ
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                Ardent D

                In Development...
                Isiris Mk II updates- in final test stage!
                Obi-Wan
                Saint-Saëns Symphonique/AKA SMJ-40
                Modula PWB
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                Natalie P Supreme
                Janus BP1 Sub


                Resistance is not futile, it is Volts divided by Amperes...
                Just ask Mr. Ohm....

                Comment

                • dwk
                  Senior Member
                  • Apr 2005
                  • 251

                  #9
                  All will be revealed in time, I suppose. But that won't stop speculation.

                  My eyes want to believe that the PE box has 225-4 showing behind the tape, but it's too blurry to be certain. Definitely a reasonable choice for a 100-per-side 3-way, but the typical HTGuide 3-way xover would undermine that value proposition a fair bit I think. I can fill out a 3-way lineup with drivers from PE, but I don't think any of them satisfy the 30 year criteria. I then started wondering whether there was something like an Eminence compression driver that might fit the bill, but it doesn't appear so - the only cheapies would be a very tough match to a 225, and also don't seem to satisfy the criteria.

                  I was guessing that the 2 unmarked boxes might be cabinet flat-packs given the lack of production woodworking facilities. They don't really have a flat-pack appropriate for the 225-4, although one of the 1.5 ft^3 sub cabinets could be repurposed with a new front baffle.

                  TLDR: I have no idea.

                  Comment

                  • Chancellor
                    Junior Member
                    • Jan 2010
                    • 12

                    #10
                    Clearly you are too dismissive of your powers of perception- your power in the Force is not to be dismissed lightly...

                    Yes, the chosen woofer for this design demonstration is the well known but sometimes under appreciated RS225-4... and those "unmarked" boxes are Denovo flatpack, ordered in consideration for possible use in this project, but possibly another.

                    There are some further steps in the design evaluation with which I am guiding my new apprentice to completion- then the utility and power of these design considerations will be revealed to all, and the construction of this "technological terror" may commence.

                    Now, actually, this is nominally a two way system, yet in an advanced implementation there are three driver parts that might be used, though only two are electrically connected. The other works on the principle of an indirect "Force push".

                    All will be revealed in time, as my new student completes his assignment.

                    My other Sith Apprentice would usually be handling these tasks, but he is still occupied with necessary activities for establishing our new facility in the more remote parts of the galaxy.

                    Comment

                    • JonMarsh
                      Mad Max Moderator
                      • Aug 2000
                      • 15261

                      #11
                      To start this off, as regards specifics and details, I've been working on two topics...
                      • Enclosure modeling- looking at a nominal "optimal" and a couple of cases either side of it- these were partly driven by possible opportuniteis for faster enclosure construction, but also recognizing that if anyone else becomes interested in this relatively simple build, it may help them to optimize for their needs and considerations.
                      • Baffle modeling- Something not discussed all that often around here, and only occasionally alluded to in some past works- like the M8a project with it's magazine article PDF. (can you believe it? 20 years ago!). Sometimes designers like to have some special tools they don't talk about often that give useful inight into optimizing the design process- well, I'm goign to talk about this a bit- you may find it interesting, if not, you can just skip over and follow the recipe or just have a good chuckle about this project.



                      The RS225 series belongs to that class of driver with relatively light cones and moderate sensitivity that can result in what some refer to as "monkey coffins". This often means tower enclosures, though there are alternative form factors, like the Q Audio 3030i, that achieve more or less the same thing with a rather different esthetic. The 3030i is one inspiration I'm looking at seriously...







                      What isn't necessarily obvious from pictures, depending on the lents type use, is how deep the cabinet design is, and the degree to which is trades front panel size for cabinet depth to get a reasonable mid 40's cut off for a 6.5" vented woofer. I like the form factor, but not the relatively high cut off point; we intend to improve on that significantly.

                      So let's kick off next with a review of some alternative suggested enclosure alignments, with only a "minimal" bit of kibitzing on my part.
                      the AudioWorx
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                      In Development...
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                      Resistance is not futile, it is Volts divided by Amperes...
                      Just ask Mr. Ohm....

                      Comment

                      • JonMarsh
                        Mad Max Moderator
                        • Aug 2000
                        • 15261

                        #12
                        1.5 cu ft RSS2265 200g Updated

                        Now, when I say, "monkey coffins", consider that Unibox suggests that a "Standard Design" for a vented enclosure for the RS225-4 would be a 51L enclosure. That's larger than the Wavecor Ardents, with two 8-3/4" drivers. For the sake of round numbers and those "Imperialists" that like to work in cu ft, we could round that up to 56L.


                        Well, initially I rebelled at that idea, and figured that 1.5L might be fairly workable and still hit some nice targets. And in fact, when considering opportunities for flat pack construction and getting SOMETHING together really fast, I decided to even consider 28L/1cu ft. So that's what we'll go over in the next posts, starting in the middle, as my thinking did, and showing the alternatives.

                        Now, that Q Audio 3030i has a nice long port exiting the back- one of the things which that form factor enables. This alone is good reason to consider it. But I'm less and less a fan of conventional vented designs, though I will show an example, and in the case of enclosure flexibility and eliminating midrange contamination, I've had very nice results lately with Dayton PR's. It may not be well known, but they're some of the best documented parts on the market, coming with a nice weight assortment, and I've had good results with them in several systems. So, the RSS265PR was selected as a "perfectionist" option to consider. The standard weights have pretty significant jumps in mass, but I've found the single disk alignment to work well in many cases, with an MMS of 275g.

                        So, let's start with the initial concept based on 1.5 cu ft:


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                        How does this look? Pretty nice, I'd say...

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                        when you consider that any reasonable positioning and boundary lift is going to raise the response by 3-5 dB by 30Hz, this looks pretty good, 100dB from a single 8" driver. (well, plus a 10" PR!).
                        Last edited by JonMarsh; 25 January 2022, 09:35 Tuesday.
                        the AudioWorx
                        Natalie P
                        M8ta
                        Modula Neo DCC
                        Modula MT XE
                        Modula Xtreme
                        Isiris
                        Wavecor Ardent

                        SMJ
                        Minerva Monitor
                        Calliope
                        Ardent D

                        In Development...
                        Isiris Mk II updates- in final test stage!
                        Obi-Wan
                        Saint-Saëns Symphonique/AKA SMJ-40
                        Modula PWB
                        Calliope CC Supreme
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                        Natalie P Supreme
                        Janus BP1 Sub


                        Resistance is not futile, it is Volts divided by Amperes...
                        Just ask Mr. Ohm....

                        Comment

                        • JonMarsh
                          Mad Max Moderator
                          • Aug 2000
                          • 15261

                          #13
                          2 cu ft Vented

                          Now, what about a vented design? And what about that 50+ liter recommendation? If you're willing to live with a larger box, and want to keep the budget down, what is possible?

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                          Essentially flat to 30Hz, nothing to complain about here!


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                          At nearly full output, it's just starting to enter the brown zone for a port ID of 3", and length (not including flares) of about 9". So, it's easy to see why the enclosure arrangement with depth has some advantages.


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                          The main drawback of the port is the midrange output and port resonance of about 670Hz, which in a three way would not likely be an issue, but for a two way perfectionist approach one might prefer to avoid. I'll explore some 2cu ft options with PR before we wrap this part up.
                          the AudioWorx
                          Natalie P
                          M8ta
                          Modula Neo DCC
                          Modula MT XE
                          Modula Xtreme
                          Isiris
                          Wavecor Ardent

                          SMJ
                          Minerva Monitor
                          Calliope
                          Ardent D

                          In Development...
                          Isiris Mk II updates- in final test stage!
                          Obi-Wan
                          Saint-Saëns Symphonique/AKA SMJ-40
                          Modula PWB
                          Calliope CC Supreme
                          Natalie P Ultra
                          Natalie P Supreme
                          Janus BP1 Sub


                          Resistance is not futile, it is Volts divided by Amperes...
                          Just ask Mr. Ohm....

                          Comment

                          • JonMarsh
                            Mad Max Moderator
                            • Aug 2000
                            • 15261

                            #14
                            1 cu ft PR Design Updated

                            The next enclosure size I considered in detail was the 1 cu ft concept- this would certainly have some limitations for low end extension, and likely would not be feasible with a ported approach, but might, "might" have some value if a PR is used- and I had a way to put together a test example quickly. For this example, we need a bit more mass and different parameters, in this size box, and I had a "hunch" about how this might model out that proved correct.

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                            Helmholtz alignments are often characterized with descriptions like electrical filters, and this example is about as close as you'll ever see to what looks like a QB3 high pass alignment with a PR, which is nominally a 6th order systems, unlike vented boxes which are 4th order. This gives a slower roll off and maintains system loading down to lower frequencies- it's popular for vented alignments, too. So, it's nearly flat to 40Hz, and gives some loading down to the mid 30's. For the size of enclosure, that's not a bad set of tradeoffs.

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                            The modeled impedance curve doesn't look like it will cause any problems, either.
                            Last edited by JonMarsh; 24 January 2022, 09:42 Monday.
                            the AudioWorx
                            Natalie P
                            M8ta
                            Modula Neo DCC
                            Modula MT XE
                            Modula Xtreme
                            Isiris
                            Wavecor Ardent

                            SMJ
                            Minerva Monitor
                            Calliope
                            Ardent D

                            In Development...
                            Isiris Mk II updates- in final test stage!
                            Obi-Wan
                            Saint-Saëns Symphonique/AKA SMJ-40
                            Modula PWB
                            Calliope CC Supreme
                            Natalie P Ultra
                            Natalie P Supreme
                            Janus BP1 Sub


                            Resistance is not futile, it is Volts divided by Amperes...
                            Just ask Mr. Ohm....

                            Comment

                            • JonMarsh
                              Mad Max Moderator
                              • Aug 2000
                              • 15261

                              #15
                              56L Updated RSS315PR 300g MMS PR

                              OK, time to look at the big boy PR options...


                              There's two ways you could do this- one with two RSS265PR, and one with a single RSS315PR- you don't need a degree in accounting to know which is more cost effective.

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                              We've definitely got some extension on the bottom end, now to below 30Hz, but the soft drift downwards in response is looking like an EBS alignment, which can be useful for a sub, but not really be what we want in a stand mount or small tower full range speaker.

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                              Last edited by JonMarsh; 24 January 2022, 10:09 Monday.
                              the AudioWorx
                              Natalie P
                              M8ta
                              Modula Neo DCC
                              Modula MT XE
                              Modula Xtreme
                              Isiris
                              Wavecor Ardent

                              SMJ
                              Minerva Monitor
                              Calliope
                              Ardent D

                              In Development...
                              Isiris Mk II updates- in final test stage!
                              Obi-Wan
                              Saint-Saëns Symphonique/AKA SMJ-40
                              Modula PWB
                              Calliope CC Supreme
                              Natalie P Ultra
                              Natalie P Supreme
                              Janus BP1 Sub


                              Resistance is not futile, it is Volts divided by Amperes...
                              Just ask Mr. Ohm....

                              Comment

                              • JonMarsh
                                Mad Max Moderator
                                • Aug 2000
                                • 15261

                                #16
                                Baffled about baffles?

                                This is where things may get either interesting or tedious, depending on your turn of mind.


                                We all know how baffle width for a tall speaker will control baffle step drop off behavior, in general terms. And that if you want to play with an existing design, without modifying the woofer crossover (or more) you better keep the main width parameter the same.

                                But, these are sort of bare bones generalizations.


                                One of my favorite tools for exploring baffle and driver interactions is Tolvan's "The Edge". If you want to have an idea of what you're getting into before you start cutting wood, it can be very helpful. And I'd say it's one of those things that may help define the difference between a good design and a perfectionist design. Because baffle step behavior may not be just a simple 6 dB drop off... compensated easily with a single pole and zero.

                                Let's investigate a bit...


                                For those interested in more about "The Edge"





                                I explored a number of baffle sizes, based on build possibilities, and will share data using more "conventional" layouts and also that which by "The Edge" seems to me to be more optimized. - and share why. Most of these are based on using or adapting flatpack cabinets available off the shelf, as most of my tools are in storage, pending a move sometime in March to a new home.

                                • 14" x 14" baffle, as is found on the 1 cu ft Denovo sub cabinet
                                • 12" x 16" Rectangular- somewhat similar ratio front panel as 3030i
                                • 12" x 19" - a larger rectangular front panel of dimensions common to many "traditional" speaker designs, and which could be obtained by cutting down the 2 cu ft Denovo sub cabinet, seeking a 1.5 cu ft cabinet design ready to construct
                                • 16" x 19". front panel- the front panel dimensions to the 2 cu Ft Denovo cabinet
                                the AudioWorx
                                Natalie P
                                M8ta
                                Modula Neo DCC
                                Modula MT XE
                                Modula Xtreme
                                Isiris
                                Wavecor Ardent

                                SMJ
                                Minerva Monitor
                                Calliope
                                Ardent D

                                In Development...
                                Isiris Mk II updates- in final test stage!
                                Obi-Wan
                                Saint-Saëns Symphonique/AKA SMJ-40
                                Modula PWB
                                Calliope CC Supreme
                                Natalie P Ultra
                                Natalie P Supreme
                                Janus BP1 Sub


                                Resistance is not futile, it is Volts divided by Amperes...
                                Just ask Mr. Ohm....

                                Comment

                                • JonMarsh
                                  Mad Max Moderator
                                  • Aug 2000
                                  • 15261

                                  #17
                                  For the baffle concept for the 1 cu ft sub enclosure, I did not prepare a "conventional" driver location example, as this is hardly a conventional format for a two way speaker.

                                  Setup of The Edge included the following parameters for analysis:

                                  • Edge sources: 40
                                  • Speaker source density: 6 (both woofer and tweeter)
                                  • Mic distance from baffle: 3m



                                  Let's start off with the woofer model that produced the smoothest modeling result with minimal dips and peaking:


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                                  Note the asymmetric location.

                                  Modelled on axis response at 3m:

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                                  Now, about the tweeter... folks often don't think about baffle step impact on tweeter response, though it can happen, and it's quite important for midrange drivers:


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                                  If I go ahead and build a 1 cu ft example to test (substantial likelihood) this is how I'll layout the baffle. I looked at pretty much every other imaginable configuration- takes a little time, but informative.
                                  the AudioWorx
                                  Natalie P
                                  M8ta
                                  Modula Neo DCC
                                  Modula MT XE
                                  Modula Xtreme
                                  Isiris
                                  Wavecor Ardent

                                  SMJ
                                  Minerva Monitor
                                  Calliope
                                  Ardent D

                                  In Development...
                                  Isiris Mk II updates- in final test stage!
                                  Obi-Wan
                                  Saint-Saëns Symphonique/AKA SMJ-40
                                  Modula PWB
                                  Calliope CC Supreme
                                  Natalie P Ultra
                                  Natalie P Supreme
                                  Janus BP1 Sub


                                  Resistance is not futile, it is Volts divided by Amperes...
                                  Just ask Mr. Ohm....

                                  Comment

                                  • JonMarsh
                                    Mad Max Moderator
                                    • Aug 2000
                                    • 15261

                                    #18
                                    12" x 16" rectangular baffle

                                    Next up is what I call the small rectangular configuration- 12" x 16", which could be approximated in a hurry with a cut down version of the 1.5 cu ft Denovo enclosure.


                                    First, the selected woofer configuration:


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                                    And the calculated response:


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                                    This should create few problems for the crossover.


                                    Next, the tweeter position and analysis:


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                                    And the modeled response:


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                                    This slight boost in the tweeter lower output range may not wind up being particularly useful, but it's much better than the dips higher up that other locations produced. I'll show some examples I saved for the next baffles modeled.


                                    This is a baffle size and response that appeals to me for a full custom build.
                                    the AudioWorx
                                    Natalie P
                                    M8ta
                                    Modula Neo DCC
                                    Modula MT XE
                                    Modula Xtreme
                                    Isiris
                                    Wavecor Ardent

                                    SMJ
                                    Minerva Monitor
                                    Calliope
                                    Ardent D

                                    In Development...
                                    Isiris Mk II updates- in final test stage!
                                    Obi-Wan
                                    Saint-Saëns Symphonique/AKA SMJ-40
                                    Modula PWB
                                    Calliope CC Supreme
                                    Natalie P Ultra
                                    Natalie P Supreme
                                    Janus BP1 Sub


                                    Resistance is not futile, it is Volts divided by Amperes...
                                    Just ask Mr. Ohm....

                                    Comment

                                    • JonMarsh
                                      Mad Max Moderator
                                      • Aug 2000
                                      • 15261

                                      #19
                                      12" x 19" Rectangular Conventional locations

                                      Next up, a more conventional bookshelf style configuration- 12" x 19" rectangular.


                                      First off, let's consider the woofer in a fairly conventional driver location:


                                      Click image for larger version

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                                      And the response:


                                      Click image for larger version

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                                      Now, the tweeter:


                                      Click image for larger version

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                                      Click image for larger version

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                                      In neither case does this look like a baffle response I would like to work with.
                                      the AudioWorx
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                                      Comment

                                      • JonMarsh
                                        Mad Max Moderator
                                        • Aug 2000
                                        • 15261

                                        #20
                                        12" x 19" Alternative locations

                                        So the question becomes, for this baffle size, can we do better? Or is this just not a great baffle dimensions for these components?


                                        Let's look at the woofer first...


                                        Click image for larger version

Name:	Obi-Wan Woofer POC Lg Rect Baffle.jpg
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                                        This was the layout selected after much experimentation for getting a smooth plot with minimum dips or peaks.


                                        Click image for larger version

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                                        Now the tweeter:


                                        Click image for larger version

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                                        Click image for larger version

Name:	Obi-Wan Tweeter 12x19 Opt baffle Response.jpg
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ID:	866564


                                        It took a bit of time to get a location that was this smooth above 1500Hz.
                                        the AudioWorx
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                                        Resistance is not futile, it is Volts divided by Amperes...
                                        Just ask Mr. Ohm....

                                        Comment

                                        • JonMarsh
                                          Mad Max Moderator
                                          • Aug 2000
                                          • 15261

                                          #21
                                          16" x 19" 2 cu ft Denovo

                                          OK, last up baffle to look at is the full 2cu ft Denovo front baffle, just for grins, which is 16" by 19".

                                          Definitely big enough for a small monkey, though he wouldn't enjoy living in it; hence, the moniker, Monkey Coffins.


                                          The story isn't much different from the previous example, so first I'll just show the tweeter response in conventional baffle position.



                                          Click image for larger version

Name:	Obi-Wan Tweeter Conv 19x16 baffle.jpg
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                                          And the response...


                                          Click image for larger version

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                                          And now the woofer calculated behavior:


                                          Click image for larger version

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                                          Click image for larger version

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                                          Next, we'll look at what might be more optimum positions for this large baffle. BTW, large baffles are harder to work with...
                                          the AudioWorx
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                                          Resistance is not futile, it is Volts divided by Amperes...
                                          Just ask Mr. Ohm....

                                          Comment

                                          • JonMarsh
                                            Mad Max Moderator
                                            • Aug 2000
                                            • 15261

                                            #22
                                            16" x 19" with optimization

                                            These are better optimized baffle position choices, out of looking at a LOT of positions, and small differences can have a surprising impact.


                                            For the woofer:



                                            Click image for larger version

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                                            Click image for larger version

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                                            And for the tweeter:



                                            Click image for larger version

Name:	Obi-Wan Tweeter Baffle Eval 19x16 baffle.jpg
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                                            Click image for larger version

Name:	16 x 19 Tweeter Response.jpg
Views:	1
Size:	75.7 KB
ID:	866572
                                            the AudioWorx
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                                            Resistance is not futile, it is Volts divided by Amperes...
                                            Just ask Mr. Ohm....

                                            Comment

                                            • JonMarsh
                                              Mad Max Moderator
                                              • Aug 2000
                                              • 15261

                                              #23
                                              Reviewing all of this, when I build a custom enclosure, I'm inclined to go with the 12" x 16" rectangular front panel, with an overall depth of 18-20", for a 40L working enclosure volume. Perhaps up to 24" deep.

                                              Probably layered bamboo board for the front (two layers) and 18mm BB ply for everything else- it's becoming a little more available lately from Woodcraft, including the big local store in Boise.


                                              But for now, the 1 cu ft enclosure at 14" x 14" baffle can model very closely on baffle behavior, so that little guy may be my first crossover and general test cab. I've got a couple of these on hand, were earmarked for Epique and PuriFi metal cone tests, but what the heck... love the one you're with.

                                              Next will be fabricating a 24" x 24" test baffle for some tweeter checks...
                                              the AudioWorx
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                                              Resistance is not futile, it is Volts divided by Amperes...
                                              Just ask Mr. Ohm....

                                              Comment

                                              • xandresen
                                                Member
                                                • Feb 2015
                                                • 48

                                                #24
                                                Originally posted by JonMarsh
                                                So, the RSS265PR was selected...
                                                All the Passive Radiator Box design windows show an Sdp of 466 cm^2 but the copy of the RSS265PR spec sheet I downloaded today shows 356 cm^2.

                                                Am I missing something?

                                                Comment

                                                • augerpro
                                                  Super Senior Member
                                                  • Aug 2006
                                                  • 1866

                                                  #25
                                                  Wouldn't these RS225 be a good candidate for your 3rd order, sealed box with woofer capacitor designs? I've been curious about using that with the RS225 in a 3-way I'm working on.
                                                  ~Brandon 8O
                                                  Please donate to my Waveguides for CNC and 3D Printing Project!!
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                                                  DriverVault
                                                  Soma Sonus

                                                  Comment

                                                  • JonMarsh
                                                    Mad Max Moderator
                                                    • Aug 2000
                                                    • 15261

                                                    #26
                                                    Originally posted by augerpro
                                                    Wouldn't these RS225 be a good candidate for your 3rd order, sealed box with woofer capacitor designs? I've been curious about using that with the RS225 in a 3-way I'm working on.
                                                    It could be, but that wouldn't help the actual LF output- just alter the tuning. Also, that works best with drivers with relatively high Qts- the RS225 doesn't fit that. It's something I could probably work up a model for, just for fun- when more spare time is available!
                                                    the AudioWorx
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                                                    Resistance is not futile, it is Volts divided by Amperes...
                                                    Just ask Mr. Ohm....

                                                    Comment

                                                    • JonMarsh
                                                      Mad Max Moderator
                                                      • Aug 2000
                                                      • 15261

                                                      #27
                                                      Originally posted by xandresen
                                                      All the Passive Radiator Box design windows show an Sdp of 466 cm^2 but the copy of the RSS265PR spec sheet I downloaded today shows 356 cm^2.

                                                      Am I missing something?
                                                      No, you're not- thanks for the catch! I was plugging in a different woofer to an existing file, and I didn't catch this issue!

                                                      I'll have updated designs (with either RSS265PR or RSS315PR by tomorrow morning! I've got some of those packed away, but probably at the back of one of the storage units- easier just to order a couple more tomorrow!
                                                      the AudioWorx
                                                      Natalie P
                                                      M8ta
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                                                      Modula Xtreme
                                                      Isiris
                                                      Wavecor Ardent

                                                      SMJ
                                                      Minerva Monitor
                                                      Calliope
                                                      Ardent D

                                                      In Development...
                                                      Isiris Mk II updates- in final test stage!
                                                      Obi-Wan
                                                      Saint-Saëns Symphonique/AKA SMJ-40
                                                      Modula PWB
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                                                      Natalie P Ultra
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                                                      Resistance is not futile, it is Volts divided by Amperes...
                                                      Just ask Mr. Ohm....

                                                      Comment

                                                      • JonMarsh
                                                        Mad Max Moderator
                                                        • Aug 2000
                                                        • 15261

                                                        #28
                                                        Enclosure calculations and graphs are all updated. PE shows RSS315PR should be back in stock around the end of the month. I ordered their last 12" Wavecor PR just to have something to play with.
                                                        the AudioWorx
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                                                        Resistance is not futile, it is Volts divided by Amperes...
                                                        Just ask Mr. Ohm....

                                                        Comment

                                                        • Bear
                                                          Super Senior Member
                                                          • Dec 2008
                                                          • 1038

                                                          #29
                                                          Originally posted by JonMarsh
                                                          Now, when I say, "monkey coffins", consider that Unibox suggests that a "Standard Design" for a vented enclosure for the RS225-4 would be a 51L enclosure. That's larger than the Wavecor Ardents, with two 8-3/4" drivers. For the sake of round numbers and those "Imperialists" that like to work in cu ft, we could round that up to 56L.


                                                          Well, initially I rebelled at that idea, and figured that 1.5L might be fairly workable and still hit some nice targets. And in fact, when considering opportunities for flat pack construction and getting SOMETHING together really fast, I decided to even consider 28L/1cu ft. So that's what we'll go over in the next posts, starting in the middle, as my thinking did, and showing the alternatives.

                                                          Now, that Q Audio 3030i has a nice long port exiting the back- one of the things which that form factor enables. This alone is good reason to consider it. But I'm less and less a fan of conventional vented designs, though I will show an example, and in the case of enclosure flexibility and eliminating midrange contamination, I've had very nice results lately with Dayton PR's. It may not be well known, but they're some of the best documented parts on the market, coming with a nice weight assortment, and I've had good results with them in several systems. So, the RSS265PR was selected as a "perfectionist" option to consider. The standard weights have pretty significant jumps in mass, but I've found the single disk alignment to work well in many cases, with an MMS of 275g.

                                                          So, let's start with the initial concept based on 1.5 cu ft:

                                                          [ATTACH=CONFIG]31819[/ATTACH]



                                                          How does this look? Pretty nice, I'd say...

                                                          [ATTACH=CONFIG]31820[/ATTACH]


                                                          [ATTACH=CONFIG]31821[/ATTACH]


                                                          [ATTACH=CONFIG]31822[/ATTACH]






                                                          when you consider that any reasonable positioning and boundary lift is going to raise the response by 3-5 dB by 30Hz, this looks pretty good, 100dB from a single 8" driver. (well, plus a 10" PR!).
                                                          The attachments are coming out invalid on my end. :cry:

                                                          It would be fun to see a Wavecor Ardent with the BD03 (8 ohm) woofers, but I know a) that I will get force choked by ET, and b) that is what the "Y" in DIY stands for. (I have seriously contemplated building the Ardent D 'rough draft' though. Good thing that there are other things to distract me...)
                                                          Welcome to Rivendell, Mr. Anderson.

                                                          Comment

                                                          • technodanvan
                                                            Senior Member
                                                            • Nov 2009
                                                            • 998

                                                            #30
                                                            So I'm learning a few things about BSC here, but how is the off-axis response going to be affected/handled with an extra wide baffle and offset drivers? You've already shown how on-axis modeling shows an...uneven...response.

                                                            Attachments on that post are also invalid for me now (Chrome), though they were fine yesterday.
                                                            - Danny

                                                            Comment

                                                            • JonMarsh
                                                              Mad Max Moderator
                                                              • Aug 2000
                                                              • 15261

                                                              #31
                                                              Originally posted by Bear
                                                              The attachments are coming out invalid on my end. :cry:

                                                              It would be fun to see a Wavecor Ardent with the BD03 (8 ohm) woofers, but I know a) that I will get force choked by ET, and b) that is what the "Y" in DIY stands for. (I have seriously contemplated building the Ardent D 'rough draft' though. Good thing that there are other things to distract me...)
                                                              Looked OK this morning, but now that one is messed up for me, too. I'll fix it tomorrow morning...
                                                              the AudioWorx
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                                                              Resistance is not futile, it is Volts divided by Amperes...
                                                              Just ask Mr. Ohm....

                                                              Comment

                                                              • JonMarsh
                                                                Mad Max Moderator
                                                                • Aug 2000
                                                                • 15261

                                                                #32
                                                                Originally posted by technodanvan
                                                                So I'm learning a few things about BSC here, but how is the off-axis response going to be affected/handled with an extra wide baffle and offset drivers? You've already shown how on-axis modeling shows an...uneven...response.

                                                                Attachments on that post are also invalid for me now (Chrome), though they were fine yesterday.
                                                                I think there is something going on with the forum- I had to redo a couple of them this morning to get them to come out right after reloading the page. They're bad for me now, too. Will completely reload that post in the AM.
                                                                the AudioWorx
                                                                Natalie P
                                                                M8ta
                                                                Modula Neo DCC
                                                                Modula MT XE
                                                                Modula Xtreme
                                                                Isiris
                                                                Wavecor Ardent

                                                                SMJ
                                                                Minerva Monitor
                                                                Calliope
                                                                Ardent D

                                                                In Development...
                                                                Isiris Mk II updates- in final test stage!
                                                                Obi-Wan
                                                                Saint-Saëns Symphonique/AKA SMJ-40
                                                                Modula PWB
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                                                                Natalie P Ultra
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                                                                Janus BP1 Sub


                                                                Resistance is not futile, it is Volts divided by Amperes...
                                                                Just ask Mr. Ohm....

                                                                Comment

                                                                • JonMarsh
                                                                  Mad Max Moderator
                                                                  • Aug 2000
                                                                  • 15261

                                                                  #33
                                                                  Originally posted by technodanvan
                                                                  So I'm learning a few things about BSC here, but how is the off-axis response going to be affected/handled with an extra wide baffle and offset drivers? You've already shown how on-axis modeling shows an...uneven...response.

                                                                  Go take a closer look at The Edge. Mic position, distance of the microphone test position, edge point density for calculations are all variable. I set this to 3M for these analysis because that's a reasonable distance for a speaker of this type and size. Moving the mic away from the center and anywhere in front of the enclosure border makes little difference if at a "normal" listening distance. Moving the driver is what makes a difference, sometimes a surprising difference. Go download it and get a few hours on it. go model some typical speakers, and see why baffle step is not as simple as some would have you believe.

                                                                  Mind you, those ripples for unoptimized baffle positions are only a few dB. But we are talking perfectionist...

                                                                  The "funny" driver positioning might not be liked by some, just like all the posts I saw on DIY Audio criticizing the appearance of the surrounds of the PuriFi drivers... non of those guys were measuring the differences in IM or other artifacts from surround resonance.

                                                                  Baffle step looks and models like diffraction as you go higher in frequency, and this is one of the few tools, actually the only tool I've found that can do this reasonably well. But Tolvan quit developing a while ago (business model not very robust I suppose). He developed a number of design programs, some of them don't have the easiest to follow user interfaces- his speaker development program will never pull me away from VituixCAD, for example!

                                                                  But how many users will do the detailed measurements and have a reference driver of sufficient flatness and extension that they could measure these characteristics accurately?

                                                                  Yes, few realize the impact of the baffle shape and driver location. that was one of the points I was trying to get across in a different way in the Speaker Design three part article for the M8a project, (48MB). Just sent a copy of that to Dhar via messages. He found it useful.
                                                                  Last edited by JonMarsh; 25 January 2022, 09:41 Tuesday.
                                                                  the AudioWorx
                                                                  Natalie P
                                                                  M8ta
                                                                  Modula Neo DCC
                                                                  Modula MT XE
                                                                  Modula Xtreme
                                                                  Isiris
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                                                                  SMJ
                                                                  Minerva Monitor
                                                                  Calliope
                                                                  Ardent D

                                                                  In Development...
                                                                  Isiris Mk II updates- in final test stage!
                                                                  Obi-Wan
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                                                                  Modula PWB
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                                                                  Resistance is not futile, it is Volts divided by Amperes...
                                                                  Just ask Mr. Ohm....

                                                                  Comment

                                                                  • JonMarsh
                                                                    Mad Max Moderator
                                                                    • Aug 2000
                                                                    • 15261

                                                                    #34
                                                                    OK, the attachments are fixed for the 1.5 cu ft enclosure post. Also started a tech drawing for the 1cu ft modified sub cabinet, and getting the tools together- should make some MDF dust this afternoon! plus cut a test baffle for the tweeter candidate...
                                                                    the AudioWorx
                                                                    Natalie P
                                                                    M8ta
                                                                    Modula Neo DCC
                                                                    Modula MT XE
                                                                    Modula Xtreme
                                                                    Isiris
                                                                    Wavecor Ardent

                                                                    SMJ
                                                                    Minerva Monitor
                                                                    Calliope
                                                                    Ardent D

                                                                    In Development...
                                                                    Isiris Mk II updates- in final test stage!
                                                                    Obi-Wan
                                                                    Saint-Saëns Symphonique/AKA SMJ-40
                                                                    Modula PWB
                                                                    Calliope CC Supreme
                                                                    Natalie P Ultra
                                                                    Natalie P Supreme
                                                                    Janus BP1 Sub


                                                                    Resistance is not futile, it is Volts divided by Amperes...
                                                                    Just ask Mr. Ohm....

                                                                    Comment

                                                                    • JonMarsh
                                                                      Mad Max Moderator
                                                                      • Aug 2000
                                                                      • 15261

                                                                      #35
                                                                      A lot of stuff going on at the home front this week, but that includes starting a test cabinet build for the 1 cu ft version.


                                                                      Click image for larger version

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                                                                      These may be used as the "monitor" speakers for the music practicing room, until the planned two way line array system can finish development and construction.

                                                                      (Line array? Think floor to ceiling, ~95-97 dB sensitivity for 2.83VRMS, and true 250W power handling. Think supply chain issues, also.)

                                                                      (Music practicing? Think deferred gratification, re-engagement with past activities)


                                                                      Click image for larger version

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                                                                      the AudioWorx
                                                                      Natalie P
                                                                      M8ta
                                                                      Modula Neo DCC
                                                                      Modula MT XE
                                                                      Modula Xtreme
                                                                      Isiris
                                                                      Wavecor Ardent

                                                                      SMJ
                                                                      Minerva Monitor
                                                                      Calliope
                                                                      Ardent D

                                                                      In Development...
                                                                      Isiris Mk II updates- in final test stage!
                                                                      Obi-Wan
                                                                      Saint-Saëns Symphonique/AKA SMJ-40
                                                                      Modula PWB
                                                                      Calliope CC Supreme
                                                                      Natalie P Ultra
                                                                      Natalie P Supreme
                                                                      Janus BP1 Sub


                                                                      Resistance is not futile, it is Volts divided by Amperes...
                                                                      Just ask Mr. Ohm....

                                                                      Comment

                                                                      • JonMarsh
                                                                        Mad Max Moderator
                                                                        • Aug 2000
                                                                        • 15261

                                                                        #36
                                                                        Front Panel drawing and routing

                                                                        Things are moving along, the test cabinet panels are all glued up.

                                                                        Unfortunately, it's a brick 15 degrees outside, so working in the garage is going to be a bit chilly- but I've cheated and kept the routers indoors so they'll be nice and warm...

                                                                        The walls are insulated (I believe; they are in the same floor plan we're having built in Middleton) but the garage doors are not in this rental house.


                                                                        Click image for larger version

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                                                                        The layout drawing reflects the front baffle layouts developed by "The Edge"; assuming all goes well, I'll build a second cabinet but with the layout mirror imaged...

                                                                        It's definitely "snug", and to nail the tweeter location will require truncation of the front plate. A DA25 would not fit in this version of the design.


                                                                        The predicted woofer response profile on this baffle doesn't quite match my "preferred" baffle size of 12" x 16", but it comes pretty close- good enough for starting crossover development after I get measurements.


                                                                        Click image for larger version

Name:	Obi-Wan Woofer POC Baffle Response NoPhase.jpg
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                                                                        The Dayton RSS315PR are backordered, but the expected availability is literally today, so if that's accurate, I might get them next week. In the mean time I bought the one remaining Wavecor PR, which seems to have been discontinued, just so I'd have something to "plug the hole" on this test build. Actually, with the available weight combinations for the Wavecor PR, things pretty much look OK, though not quite matching the RSS315PR parts.

                                                                        Let's see what I can get done this weekend...
                                                                        the AudioWorx
                                                                        Natalie P
                                                                        M8ta
                                                                        Modula Neo DCC
                                                                        Modula MT XE
                                                                        Modula Xtreme
                                                                        Isiris
                                                                        Wavecor Ardent

                                                                        SMJ
                                                                        Minerva Monitor
                                                                        Calliope
                                                                        Ardent D

                                                                        In Development...
                                                                        Isiris Mk II updates- in final test stage!
                                                                        Obi-Wan
                                                                        Saint-Saëns Symphonique/AKA SMJ-40
                                                                        Modula PWB
                                                                        Calliope CC Supreme
                                                                        Natalie P Ultra
                                                                        Natalie P Supreme
                                                                        Janus BP1 Sub


                                                                        Resistance is not futile, it is Volts divided by Amperes...
                                                                        Just ask Mr. Ohm....

                                                                        Comment

                                                                        • JonMarsh
                                                                          Mad Max Moderator
                                                                          • Aug 2000
                                                                          • 15261

                                                                          #37
                                                                          initial test data from 1 cu ft POC enclosure

                                                                          The "Proof Of Concept" test box has been completed, and some basic driver tests finished- enough to start a crossover design proposal soon.

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                                                                          These cabinets are expected to be mirror imaged if/when a stereo pair is built (probably just for the 12 X 16" rectangular baffle, and 1.5 cu ft volume, net).
                                                                          Measurements were taken for polar response on both sides of the horizontal centers, and were surprisingly good even on the "off" axis, but I'm just going to show for now for the design intention. In modeling for the crossover, I may use from 30 degrees on the outside to 50 degrees on the inside.

                                                                          On axis for the test tweeter, with distortion:


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                                                                          (experience with the DA25 and some other parts shows that with the breakup mode notch filter in place, most of the resonance mode amplification of distortion products will not appear).


                                                                          Zero to 30 degree polar:

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                                                                          And zero to 50 degree:


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                                                                          the AudioWorx
                                                                          Natalie P
                                                                          M8ta
                                                                          Modula Neo DCC
                                                                          Modula MT XE
                                                                          Modula Xtreme
                                                                          Isiris
                                                                          Wavecor Ardent

                                                                          SMJ
                                                                          Minerva Monitor
                                                                          Calliope
                                                                          Ardent D

                                                                          In Development...
                                                                          Isiris Mk II updates- in final test stage!
                                                                          Obi-Wan
                                                                          Saint-Saëns Symphonique/AKA SMJ-40
                                                                          Modula PWB
                                                                          Calliope CC Supreme
                                                                          Natalie P Ultra
                                                                          Natalie P Supreme
                                                                          Janus BP1 Sub


                                                                          Resistance is not futile, it is Volts divided by Amperes...
                                                                          Just ask Mr. Ohm....

                                                                          Comment

                                                                          • JonMarsh
                                                                            Mad Max Moderator
                                                                            • Aug 2000
                                                                            • 15261

                                                                            #38
                                                                            RS225-4 graphs

                                                                            And looking at the RS225-4, things turn out pretty much as expected:


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                                                                            Polar is shown for 0-30 degrees...


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                                                                            And for 0 to 50 degrees... this is a very good level of performance for an 8" driver- pretty much class leading.

                                                                            For reference, the -10 dB graph level corresponds to 90 dB SPL at 1M.


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                                                                            Last edited by JonMarsh; 31 January 2022, 09:08 Monday.
                                                                            the AudioWorx
                                                                            Natalie P
                                                                            M8ta
                                                                            Modula Neo DCC
                                                                            Modula MT XE
                                                                            Modula Xtreme
                                                                            Isiris
                                                                            Wavecor Ardent

                                                                            SMJ
                                                                            Minerva Monitor
                                                                            Calliope
                                                                            Ardent D

                                                                            In Development...
                                                                            Isiris Mk II updates- in final test stage!
                                                                            Obi-Wan
                                                                            Saint-Saëns Symphonique/AKA SMJ-40
                                                                            Modula PWB
                                                                            Calliope CC Supreme
                                                                            Natalie P Ultra
                                                                            Natalie P Supreme
                                                                            Janus BP1 Sub


                                                                            Resistance is not futile, it is Volts divided by Amperes...
                                                                            Just ask Mr. Ohm....

                                                                            Comment

                                                                            • JonMarsh
                                                                              Mad Max Moderator
                                                                              • Aug 2000
                                                                              • 15261

                                                                              #39
                                                                              impedance plots

                                                                              Impedance plots and data were also recorded...



                                                                              note, that due to delayed availability of the RSS315PR, a Wavecor 12" PR tuned as close as possible with it's weight set was employed; pretty much nailed the modeled FB.

                                                                              The RSS315PR are expected back in stock very soon, and I have some backordered for now.


                                                                              The tweeter impedance is shown here, and I like that the Fs resonance is very symmetrical and easy to create a Zobel network for.


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                                                                              A reminder, for this 1 cu ft nominal enclosure design, the predicted SPL for the RSS315PR is:





                                                                              From the impedance and distortion data I think taking this down to 1700-1800 Hz with a fast roll off network should be workable. But the devil is in the details; I also want to use a Quasi-series network with this design study, as used in the Modula MT and Natalie P. Most likely the ultimate slopes will look like an LR6, if something like that existed in the normal literature.


                                                                              I probably will not build two at this size, but because the baffle step behavior modeled for this front panel design and for the 12" x 16" design are so similar, it may be feasible to use basically the same crossover network.
                                                                              Last edited by JonMarsh; 31 January 2022, 09:10 Monday.
                                                                              the AudioWorx
                                                                              Natalie P
                                                                              M8ta
                                                                              Modula Neo DCC
                                                                              Modula MT XE
                                                                              Modula Xtreme
                                                                              Isiris
                                                                              Wavecor Ardent

                                                                              SMJ
                                                                              Minerva Monitor
                                                                              Calliope
                                                                              Ardent D

                                                                              In Development...
                                                                              Isiris Mk II updates- in final test stage!
                                                                              Obi-Wan
                                                                              Saint-Saëns Symphonique/AKA SMJ-40
                                                                              Modula PWB
                                                                              Calliope CC Supreme
                                                                              Natalie P Ultra
                                                                              Natalie P Supreme
                                                                              Janus BP1 Sub


                                                                              Resistance is not futile, it is Volts divided by Amperes...
                                                                              Just ask Mr. Ohm....

                                                                              Comment

                                                                              • Zvu
                                                                                Senior Member
                                                                                • Oct 2013
                                                                                • 434

                                                                                #40
                                                                                God i love this this part of the process.
                                                                                Tesla; George Carlin;

                                                                                Comment

                                                                                • JonMarsh
                                                                                  Mad Max Moderator
                                                                                  • Aug 2000
                                                                                  • 15261

                                                                                  #41
                                                                                  Originally posted by Zvu
                                                                                  God i love this this part of the process.

                                                                                  Yeah, while it's a fair amount of work, it's a lot of fun seeing things come together!
                                                                                  the AudioWorx
                                                                                  Natalie P
                                                                                  M8ta
                                                                                  Modula Neo DCC
                                                                                  Modula MT XE
                                                                                  Modula Xtreme
                                                                                  Isiris
                                                                                  Wavecor Ardent

                                                                                  SMJ
                                                                                  Minerva Monitor
                                                                                  Calliope
                                                                                  Ardent D

                                                                                  In Development...
                                                                                  Isiris Mk II updates- in final test stage!
                                                                                  Obi-Wan
                                                                                  Saint-Saëns Symphonique/AKA SMJ-40
                                                                                  Modula PWB
                                                                                  Calliope CC Supreme
                                                                                  Natalie P Ultra
                                                                                  Natalie P Supreme
                                                                                  Janus BP1 Sub


                                                                                  Resistance is not futile, it is Volts divided by Amperes...
                                                                                  Just ask Mr. Ohm....

                                                                                  Comment

                                                                                  • JonMarsh
                                                                                    Mad Max Moderator
                                                                                    • Aug 2000
                                                                                    • 15261

                                                                                    #42
                                                                                    I've finished an initial design pass for the crossover, and though it's a bit more complicated than I'd prefer, it also offers the basis for some options like a presence range control, due to the EQ filter necessary to fix a bump in the tweeter's response centered at 4kHz.

                                                                                    In some ways, I'll grant this project is somewhat quixotic, but that actually makes it somewhat more fun in some ways... combining a titanium tweeter than can trace its lineage back to early Avalon products, with one of the earliest aluminum cone drivers from PE is definitely a retrospective effort. Partly, I'm just curious to see if some careful design work will make this an interesting project in the 1.5 cu ft version with the optimum front panel.


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                                                                                    Click image for larger version

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                                                                                    the AudioWorx
                                                                                    Natalie P
                                                                                    M8ta
                                                                                    Modula Neo DCC
                                                                                    Modula MT XE
                                                                                    Modula Xtreme
                                                                                    Isiris
                                                                                    Wavecor Ardent

                                                                                    SMJ
                                                                                    Minerva Monitor
                                                                                    Calliope
                                                                                    Ardent D

                                                                                    In Development...
                                                                                    Isiris Mk II updates- in final test stage!
                                                                                    Obi-Wan
                                                                                    Saint-Saëns Symphonique/AKA SMJ-40
                                                                                    Modula PWB
                                                                                    Calliope CC Supreme
                                                                                    Natalie P Ultra
                                                                                    Natalie P Supreme
                                                                                    Janus BP1 Sub


                                                                                    Resistance is not futile, it is Volts divided by Amperes...
                                                                                    Just ask Mr. Ohm....

                                                                                    Comment

                                                                                    • technodanvan
                                                                                      Senior Member
                                                                                      • Nov 2009
                                                                                      • 998

                                                                                      #43
                                                                                      Yep, that look like a patented Jon Marsh-style crossover! Can it be built under $100 as well...not through PE, I think. Maybe if one were to wind their own inductors?

                                                                                      Which specific tweeter is that? I get a couple titanium versions with my Google-Fu this morning. Granted, I have not caffeinated yet.
                                                                                      - Danny

                                                                                      Comment

                                                                                      • JonMarsh
                                                                                        Mad Max Moderator
                                                                                        • Aug 2000
                                                                                        • 15261

                                                                                        #44
                                                                                        Originally posted by technodanvan
                                                                                        Yep, that look like a patented Jon Marsh-style crossover! Can it be built under $100 as well...not through PE, I think. Maybe if one were to wind their own inductors?

                                                                                        Which specific tweeter is that? I get a couple titanium versions with my Google-Fu this morning. Granted, I have not caffeinated yet.

                                                                                        It's the PE MB Quart buyout, no worries about running out, they have over 300 in stock.


                                                                                        MB Quart 95-7119 1" Titanium Dome Tweeter with Truncated Faceplate 6 OhmThe new old stock 95 7119 is a 1" titanium dome tweeter which was manufactured in Germany by MB Quart, who was always known for producing extremely high quality drivers, especially high frequency drivers. This tweeter features a unique truncated on one side faceplate that is perfect for lowering center to center distance to a midrange in 2-way MT and 3-way designs. The solid titanium dome's low weight and rigid structure ensures accurate response to well above the capability of the human ear. Keeping unwanted resonances under control, a rubber surround supports the 1" titanium dome to eliminate the harshness that is sometimes associated with metal dome tweeters. A damped pole vent and rear chamber pushes the Fs down to 860 Hz giving this tweeter the ability to handle low crossover frequencies for easy transition to a midrange driver. The 95 7118 also features a secondary bucking magnet which concentrates the magnetic field on the voice coil gap improving efficiency and overall out capability. Finally, the stylish reinforced plastic faceplate includes an integrated perforated steel grill to protect the fragile dome for years of worry free operation.Limited quantities! Get these classic tweeters from MB Quart while they are still available. After they are gone you may never see them on the market again.



                                                                                        I used my own coil winder for years, but left that behind at Twaale's.

                                                                                        No reason we can't propose a budget and perfectionist version of the crossover. Thing is, once you've spent the time building the cabinet and everything, some places don't make sense to cut corners. I view keeping the basic driver cost low is providing leverage for spending on other stuff as you choose- for example, my full build set will almost certainly use a double layer LBL front panel, and the rest out of BB ply. Building this test box reminds me once again of what I don't like about MDF.

                                                                                        with a 12"x16" front baffle, the interior depth will need to be 19"-20". Plenty of length for those needing to use a port on a budget. And still reminiscent of the 3030i.

                                                                                        PS, I rarely work without caffeination... its just not productive!
                                                                                        the AudioWorx
                                                                                        Natalie P
                                                                                        M8ta
                                                                                        Modula Neo DCC
                                                                                        Modula MT XE
                                                                                        Modula Xtreme
                                                                                        Isiris
                                                                                        Wavecor Ardent

                                                                                        SMJ
                                                                                        Minerva Monitor
                                                                                        Calliope
                                                                                        Ardent D

                                                                                        In Development...
                                                                                        Isiris Mk II updates- in final test stage!
                                                                                        Obi-Wan
                                                                                        Saint-Saëns Symphonique/AKA SMJ-40
                                                                                        Modula PWB
                                                                                        Calliope CC Supreme
                                                                                        Natalie P Ultra
                                                                                        Natalie P Supreme
                                                                                        Janus BP1 Sub


                                                                                        Resistance is not futile, it is Volts divided by Amperes...
                                                                                        Just ask Mr. Ohm....

                                                                                        Comment

                                                                                        • JonMarsh
                                                                                          Mad Max Moderator
                                                                                          • Aug 2000
                                                                                          • 15261

                                                                                          #45
                                                                                          BOM's and supply chains... and greed?

                                                                                          Preparing some initial BOM's has proven to be an "interesting" exercise...


                                                                                          Now, for this build, I've been planning a somewhat schizophrenic approach-
                                                                                          • A budget crossover build that hits electrical targets but sticks with high value parts in relation to cost, like Jantzen Cross Cap, Dayton film caps, etc
                                                                                          • A semi-perfectionist build, particualrly with upgraded capacitors to what I'd call high mid-grade, since the crossover point is high enough that the things we usually care about for mids and tweeters in a three way apply across the board to the single crossover point, nominally 1700 Hz.


                                                                                          One data point causing me to do a more complete and compelling review is the startling price increases I've seen for what I'd call premium upper mid grade capacitors, and "budget" high end capacitors. Take Jantzen... many of their better caps, like the Z-Superior and Alumen film and foil have seen 60% price increases since my last big orders.

                                                                                          Now, when caps like that are going up at double the rate of Boise real estate, something is out of whack!

                                                                                          So, this current effort has involved a lot of new "survey and evaluation" efforts, and I also plan some technical tests in the near future, once we get moved and I can unpack my APx555, and doing literal distortion tests of crossovers with loads. I figure it's a good idea to have some hard measurements to back up subjective evaluations- or, is it the other way around?

                                                                                          One of the few bright points in this situation is the relative performance versus cost of the Clarity CSA copper connect series, for a premium mid grade offering, and also that my past favored UK distributor has good stock on Clarity parts, including the relatively elusive MR series I enjoyed so much in the past, but which have dried up in NA. (my favorite NA distributor carries mostly their own brand of capacitors, Solen.) I am also looking at combining Audyn true copper caps with the CSA, based on some initial experiments after picking up a variety of Audyn caps to evaluate in the latter half of 2021. This boosts the price a bit, but for achieving larger values with good sonics, it may be an effective path. For low impedance tweeters and low crossover points, the capacitance size goes up quite a bit.

                                                                                          All for now, but stay tuned... the rest of February will likely be quiet, though later this month I may post my preliminary BOMs being ordered.
                                                                                          the AudioWorx
                                                                                          Natalie P
                                                                                          M8ta
                                                                                          Modula Neo DCC
                                                                                          Modula MT XE
                                                                                          Modula Xtreme
                                                                                          Isiris
                                                                                          Wavecor Ardent

                                                                                          SMJ
                                                                                          Minerva Monitor
                                                                                          Calliope
                                                                                          Ardent D

                                                                                          In Development...
                                                                                          Isiris Mk II updates- in final test stage!
                                                                                          Obi-Wan
                                                                                          Saint-Saëns Symphonique/AKA SMJ-40
                                                                                          Modula PWB
                                                                                          Calliope CC Supreme
                                                                                          Natalie P Ultra
                                                                                          Natalie P Supreme
                                                                                          Janus BP1 Sub


                                                                                          Resistance is not futile, it is Volts divided by Amperes...
                                                                                          Just ask Mr. Ohm....

                                                                                          Comment

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