Even slower work....

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  • JonMarsh
    Mad Max Moderator
    • Aug 2000
    • 15259

    Even slower work....

    Takes the most time of all!

    Just a little update for those curious about our April 1st Prank, the Fools Day blurb that wasn't a Fools Day story....



    At some points in the assembly it's hard to remember what it is I'm building, because it's not very recognizable..... :?




    As things progress, it because a little more obvious... keep in mind, unlike my usual projects, there's no CAD drawing lurking anywhere on a hard drive... this is strictly extemporaneous engineering and construction... :LOL:




    But at this stage, sitting in the living room, just for effect and to gauge how it will look when finished *in* a living room, it becomes a little more obvious what it's all about. 8)


    Stay tuned....

    -Jon




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  • Pat
    Super Senior Member
    • Aug 2000
    • 1637

    #2
    Jon,
    Looking good so far...




    Pat's Page
    Pat's Page

    Comment

    • David Meek
      Moderator Emeritus
      • Aug 2000
      • 8938

      #3
      Jon,

      Maybe we should start calling you "Dr. Clamp". :B

      Seriously though, the Part is shaping up nicely!

      P.S. I have NO idea how to put the two dots above the "a". What keyboard mapping do you use?




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      • JonMarsh
        Mad Max Moderator
        • Aug 2000
        • 15259

        #4
        Hi Pat and David!

        My big "secret" for the "Arvo Pärt" is the "Character Map" program, a utility included in Windows, usually in the Programs/Accessories folder, but in XP they put it in the system tools folder- go figure. You can select any of the special characters and copy them to the clipboard.

        I was hoping to get the drivers loaded last night, but instead I spent much of the evening on the phone with my step mom, (who's remarried to her best friend's husband Harley) and Harley (both my dad and her best friend passed away some years ago). Harley was diagnosed with cancer earlier this year, and is undergoing chemo, but so far doing pretty well. They can't kill the cancer (it's also in the liver; the main tumor was removed from his colon), but there's hope to prolong the length and quality of life considerably.

        I got them their first CD player last Xmas; they're in their late 70's. A different generation, for sure.

        Regards,

        Jon




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        Comment

        • David Meek
          Moderator Emeritus
          • Aug 2000
          • 8938

          #5
          Jon, I'm sorry to hear about your step-dad's cancer. I know that doctors can do some really impressive things in treatments now, and the near-term research is showing some even more successful avenues. It's good that they have a decent prognosis for keeping his life quality up, too. We'll keep him in our thoughts.




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          • JonMarsh
            Mad Max Moderator
            • Aug 2000
            • 15259

            #6
            Thanks for the kind words, David. He seems to be in good spirits, and is definitely putting up a good fight- pretty scrappy for 78!

            Regards,

            Jon




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            Comment

            • Jack Gilvey
              Senior Member
              • Aug 2001
              • 510

              #7
              I'd really like to know more about this...throw me a bone?

              Comment

              • JonMarsh
                Mad Max Moderator
                • Aug 2000
                • 15259

                #8
                Hi Jack,

                The "Arvo Pärt" project started as a little bit of a goof write up for April Fools Day; you can find the original post with some description in Audio Hideout here.

                This is an experimental dipole speaker project, and since it's based on a lot of the development concepts of Sigfried Linkwitz, well, we had to name it after a composer, too, like the company he worked/works for, Audio Artistry (Dvorak, Beethoven, Vivaldi are their models). A dipole speaker radiates out of phase front to rear, using both the front wave from the driver and the rear wave, the concept being that the resulting radiation pattern (a figure 8) will have large nulls at the side, and substantially reduce the room interaction. Needless to say, there are a lot of tricky issues in the design, and since there's a lot of cancellation going on in the lower mid to low frequencies, it requires a lot more driver excursion and swept area than a box speaker. But properly done, they can cut out a lot of the "room sound", and produce clarity that is often only available through headphones.

                We've done one other dipole speaker system in the past, this was the Legacy Whisper Klone project, who's construction is described in detail at http://klone-audio.com/. This speaker is only a dipole in the range of about 100 Hz to 300 Hz; the midrange are sealed back.

                The Arvo Pärt is patterned after the Vivaldi to a degree, however, with some substantial driver upgrades in some cases. For example, I'm using the M8a midwoofer instead of the 21W8554 Scanspeak. There are cone mode issues in the 21W8554 which have always colored the sound in the midrange, which are revealed by an examination of the impedance curve and nearfield multi position microphone sweeps. These show the first cone mode at 800 Hz, and subsequent ones in the 1.2 and 1.8 kHz region.





                In my opinion, these characteristics make it less than completely suitable to run up to 1.4-1.5 kHz at the crossover point for the tweeter. But, when the Vivaldi's were originally designed, there may not have been anything much better available.


                The M8a driver I'm going to try for this application is pistonic up until it's first mode at 2.5 kHz.

                I'm not using the 10" woofers of the Vivaldi design, either; I've found some promising ones (Titanic II) (which are actually 11's) which have about 18 mm Xmax, and the first cone mode at about 700 Hz. Like most long throw woofers, they have a high VC inductance, and a natural roll off of 6 dB /octave above 75 Hz due to this inductance; this aids in providing the 6 dB/octave dipole equalization without an active or passive line equalizer.

                A lot of questions still to be answered about the feasiblity; I think I have a workable passive crossover concept, but the proof will be in the puddin', as they say.


                Regards,

                Jon




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                Comment

                • Jack Gilvey
                  Senior Member
                  • Aug 2001
                  • 510

                  #9
                  Thanks, Jon!

                  But properly done, they can cut out a lot of the "room sound", and produce clarity that is often only available through headphones.
                  This is just what I found when I owned MMG's. I've got some Adire DPL-12 dipole woofers I'd love to work into a project like this.

                  Comment

                  • JonMarsh
                    Mad Max Moderator
                    • Aug 2000
                    • 15259

                    #10
                    Yeah, we are thinking about picking up some of the Adire DPL12 woofers on their current pre-buy, as another driver to evaluate. The price is right, and most of the characteristics look fairly good; it's very well made, and some correspondence with Dan indicates the first cone mode is at about 600 Hz, which should be OK.

                    The original Vivaldi's used 10" woofers on the lower end, and the Arvo Part will use "super 10's", which are actually 11's. I'm tempted to try the Adire drivers in this position, or more likely in a dipole "sub" with the drivers in push/pull (wired out of phase, and acoustically out of phase (so they match up), to cancel even order distortion). On the otherhand, I'm also going to try this system with my BPD1203's in a stereo sub, too. So, who knows what the final configuration will be?

                    -Jon




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                    Comment

                    • Jack Gilvey
                      Senior Member
                      • Aug 2001
                      • 510

                      #11
                      These would likely work spectacularly. Pricey buggers, though:


                      http://lambdacoustics.com/drivers/DIPOLE12.html

                      Comment

                      • JonMarsh
                        Mad Max Moderator
                        • Aug 2000
                        • 15259

                        #12
                        Well, rating a 12 for running up to 2 kHz is pretty aggressive; I find maintaining pistonic behavior in a we above 600 Hz highly unlikely. Even Eton's have their limits well below that.

                        At $390, the price is pretty deluxe. I think the Adire DPL12 would be a more interesting starting point, and is pretty zoot and well built for the price.

                        I'm not finished evaulating the Titanic II 10", but it's very promising. It's also actually an 11" driver, so you might say I'm "cheating" a bit. First cone mode is at about 700. Price on either of these is much more reasonable- I'm crazy, but I'm not insane (or rich!) you know! :LOL: It would be fun to look at the Lambda, I just would be surprised if it really brought something to the party to justify the price.

                        Regards,

                        Jon




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                        Comment

                        • Jack Gilvey
                          Senior Member
                          • Aug 2001
                          • 510

                          #13
                          I put together a test baffle today from some 3/4" marine ply, basically the same as Linkwitz's sketch g below:


                          The baffle is 2'W x 4'H with 8" wings (d) extending back. Two DPL12's are mounted on the bottom half of the baffle.
                          So far, very cool. The smoothness is impressive, definitely a unique character (or lack thereof)to the sound, and it seems to go at least as deep as my PR sub (very surprizing given the lack of any eq), although it can't get as loud before overexcursion. I settled upon a 6-ohm resistor across one unwired VC of each driver resulting in a Qts of .5 or so (resistively damped operation, or RDO), and the wired coils are paralleled presenting a 4-ohm load to the amp.

                          Anyway, I've just begun to play with it, I'll try and get some FR numbers soon if I can find my disc in all this mess.

                          Comment

                          • JonMarsh
                            Mad Max Moderator
                            • Aug 2000
                            • 15259

                            #14
                            Hey, Jack,

                            Sounds like you're having fun there! This is your Adire's your playing with, correct? I think ThomasW will be ordering those for us to evaluate in the next couple of days- they seem to be a slam dunk for either dipole or IB applications.

                            To get the same SPL, you'll need about 4X the driver area as for a sealed box, somewhere near 6X to 8X compared with a high performance PR/reflex.

                            The articulation and lack of "character" (i.e., coloration) is the really appealing thing about well setup dipoles that's hard to match and impossible to beat, IMO.

                            Regards,

                            Jon




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                            Comment

                            • Jack Gilvey
                              Senior Member
                              • Aug 2001
                              • 510

                              #15
                              Yep, the DPL-12's. I'm going to try a fit the other two onto the baffle tomorrow...lotsa fun.

                              Comment

                              • JonMarsh
                                Mad Max Moderator
                                • Aug 2000
                                • 15259

                                #16
                                A lot of you have been pestering me for a status update on the AP's. The current stage is "hold"- as I've been traveling so much on business I hardly recognize my home anymore. Below is the last pic I took of them-




                                Now I'm in the process of updating the computer based crossover design from more detailed measurements of the drivers in baffle, at several distances from the speaker, and evaluating the options and tradeoffs. I'll be ordering crossover parts shortly, and hope to fine tune the passive crossover over the Thanksgiving shutdown (one week for our company- cause most divisions are pretty slow, where as we're swamped with things to do in the power semi group).

                                I might even make pretty bases for them then! But then I'm also planning on working on the line array- I think it's going to be a busy week.

                                Best regards,

                                Jon




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                                Comment

                                • JohnR
                                  Junior Member
                                  • Oct 2002
                                  • 7

                                  #17
                                  At $390, the price is pretty deluxe.
                                  Bob Reimer has them on special this month for $209. I believe his regular price is $265.

                                  http://www.creativesound.ca/products.php?make=Lambda

                                  Jon, I'm not that far from you, if you would be interested in measuring one I can drive down there on a weekend.

                                  JohnR

                                  Comment

                                  • JonMarsh
                                    Mad Max Moderator
                                    • Aug 2000
                                    • 15259

                                    #18
                                    Interesting parameters- I checked them out on the CSS site. At $209, certainly more reasonable. I was a little surprised the Xmax wasn't a bit higher.

                                    Last week we got in the DPL 12's on the pre-order. They're optimized for dipole operation, though the Qts isn't as high as the Lambda.



                                    DPL 12 Dipole woofer


                                    As you can see, the frame design is quite open, and the rear pole peice vent is quite large; all for minimizing any chuffing or noise during low frequency excursions.


                                    A quick view of the Titanic MkII "10" driver (it's an 11) is quite similar:





                                    Titanic MkII 10" Driver


                                    The Titanic 10 uses a flat progressive spider with the leads woven into the spider; it claims a 16 mm Xmax. It's high inductance is actually an asset with regards to dipole designs- or at least the one I'm working on.


                                    Drivers like the DPL12 or the Lambda might be best for an H frame dipole "sub" to work with the AP. It would be interesting to have a chance to measure the Lambda's if the DPL12's don't work out. Thanks for the offer.

                                    But first I'll probably try the AP's with my BP1203's in a sealed sub. The 1203's have the travel for a dipole configuration, (24 mm!), but the Qts is lower than what I'd want. But they're fine for a Linkwitz transform sealed box or even a ported system.

                                    Regards,

                                    Jon




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                                    Comment

                                    • sfdoddsy
                                      Senior Member
                                      • Sep 2000
                                      • 496

                                      #19
                                      I'm (slowly) building a test baffle that is a like a cross between yours and the Orion. Curse my idliness.

                                      There was, however, someone at the Parts Express board who compared the DPL12 and the Titanic and found chuffing from the Titanic if my memory serves and none from the DPL12. If you do a search for Adire you should find it.

                                      Steve




                                      Steve's DIY Dipoles
                                      Steve's OB Journey

                                      Comment

                                      • JonMarsh
                                        Mad Max Moderator
                                        • Aug 2000
                                        • 15259

                                        #20
                                        I'll have to take a look at that and see-

                                        I'm only planning to use the Titanic's down to about 75 Hz, rolling off below that, so it may not be an issue for me. In doing some sweeps with an oscillator and power amp, I haven't observed any issues with the 10" (11) Titanic. Was it the 10" or 12" referred to? I guess I'll find out.

                                        -Jon




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                                        Comment

                                        • JonMarsh
                                          Mad Max Moderator
                                          • Aug 2000
                                          • 15259

                                          #21
                                          Well, in response to a few questions about some of my driver and configuration choices, I thought I'd post a brief philosophical explanation (VERY brief) and a "teaser" of a plot.

                                          One of my goals with the AP (beyond the initial "spoof" fun of the April Fools Day project
                                          has been to develop a usable dipole speaker with a minimal amount of active EQ or crossover support; i.e., "simple" configuration with if possible, a wholly passive crossover. This has required selecting drivers and driver wiring impedances, as well as the baffle design, to try to optimize the behavior "open loop" - before the application of the crossover and passive equalization. Though this hasn't quite been a "shot in the dark", there's certainly some uncertainty involved, particularly since this is only my second conventional dynamic driver dipole speaker system project. These issues account for my choice of the Titanic MkII 10" driver over some other worthy candidates, as well as the baffle desigin for the "mid-woofers" and the LF drivers.

                                          There's many a slip twixt the cup and the lip, as Willy the Shake would put it (thanks, Joni), but below I'll show you the reason why I think some of these decisions are on the right track...



                                          Raw MLS response, no filtering, in room, 40 msec window

                                          This is the in room response at the "listening position" for the combination of the bass and mid-woofer drivers, with a long time window, (to get LF measurement below 200 Hz), so there's some ripples in the midrange due to room reflections and combfilter effects (this isn't in a treated room).

                                          BTW, this is just with the two series arrays of the bass drivers (4 ohm + 4 ohm in series) and midwoofer drivers (8 ohms + 8 ohms in series) wired in parallel, connected direct to the amplifier, with NO crossover, and NO EQ.

                                          I think this will "clean up" very well with the relatively simple crossover for the woofers to midbass that I had in mind, as well as a version of the M8A crossover for the upper drivers to tweeter.


                                          Best regards,

                                          Jon




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                                          We'll screw up the other planets later....
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                                          Resistance is not futile, it is Volts divided by Amperes...
                                          Just ask Mr. Ohm....

                                          Comment

                                          • sfdoddsy
                                            Senior Member
                                            • Sep 2000
                                            • 496

                                            #22
                                            Jon,

                                            I just took delivery of my DPL12s. At $70 each I can't complain about the price.

                                            However, I did notice that mine have a grill over the pole vent and yours appear not to. Did you remove yours?


                                            Steve




                                            Steve's DIY Dipoles
                                            Steve's OB Journey

                                            Comment

                                            • JonMarsh
                                              Mad Max Moderator
                                              • Aug 2000
                                              • 15259

                                              #23
                                              Interesting. Mine don't, and I didn't remove any. I suspect it's a measure to keep dust or small critters out of the inside of the gap; usually the back of the driver is inside a box, where nothing can get to it!

                                              Regards,

                                              Jon




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                                              Comment

                                              • sfdoddsy
                                                Senior Member
                                                • Sep 2000
                                                • 496

                                                #24
                                                Another question (and it is unlikely to be the last), but how do you think the top panel would go laid on its side and used as a center channel. Is the crossover low enough to cut down some of the lobing problems?

                                                Steve




                                                Steve's DIY Dipoles
                                                Steve's OB Journey

                                                Comment

                                                • JonMarsh
                                                  Mad Max Moderator
                                                  • Aug 2000
                                                  • 15259

                                                  #25
                                                  Interesting thought. The crossover is at 1.25 kHz. The dispersion would be equivalent to a dul 4" D'Apollito with a miniature tweeter laid on it's side, crossed over at 2.5 kHz. The total width of the drivers this way may lead to some narrowing of the dispersion near the crossover region, but the tweeter would compensate; I'd be reluctant to just "guess" about it, but recommend measuring. The problem is that it's equivalent to the vertical window, which always includes some crosover phase shifts with offset angle and the possiblity of getting into nulls, though the narrow crossover region and dual drivers helps with all that.

                                                  Personally, my favorite configuration for a center is like one we designed recently for a friend, with two flanking midwoofers (Eton 880's in this case), a midrange in the center below region (MB 2" titanium dome, crossover about 750 Hz) and tweeter above the midrange (Focal TC120dx2). That's a great center channel setup, and has excellent off axis performance and speed intelligibility.

                                                  -Jon




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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
                                                  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

                                                  • sfdoddsy
                                                    Senior Member
                                                    • Sep 2000
                                                    • 496

                                                    #26
                                                    I'm looking at an inexpensive dipole center, and since my dipole drivers don't have shielded versions I thought yours might be interesting.

                                                    Normally I just use a phantom center, but now that I have an SACD/DVD-A player a dedicated center is probably necessary.

                                                    Steve




                                                    Steve's DIY Dipoles
                                                    Steve's OB Journey

                                                    Comment

                                                    • JonMarsh
                                                      Mad Max Moderator
                                                      • Aug 2000
                                                      • 15259

                                                      #27
                                                      There aren't sheilded versions of the M8a available, though there is of the Vifa XT. It's response isn't quite the same as the "standard" version, though. The MB dome mids weren't very expensive, and they've worked quite well in this application; their low end resonance is about 350 Hz. There is a shielded version of the 6-1/2 HiVi; that might be a workable combination, with minor adjustments to the crossover.

                                                      Jon




                                                      Earth First!
                                                      _______________________________
                                                      We'll screw up the other planets later....
                                                      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

                                                      • sfdoddsy
                                                        Senior Member
                                                        • Sep 2000
                                                        • 496

                                                        #28
                                                        Ah, the Parts Express catalogue is wrong then. They have the M8a listed as shielded. Mind you, the center would be on a stand above and slightly away from the monitor. I'll keep fiddling.

                                                        Steve




                                                        Steve's DIY Dipoles
                                                        Steve's OB Journey

                                                        Comment

                                                        • Dennis H
                                                          Ultra Senior Member
                                                          • Aug 2002
                                                          • 3791

                                                          #29
                                                          There's a shielded version of the Seas 18W, if you want to stay in the Excel family.

                                                          Comment

                                                          • intelonetwo
                                                            Member
                                                            • Jan 2003
                                                            • 48

                                                            #30
                                                            Hi All,
                                                            I am about to embark on this IB design using the following drivers:
                                                            Vifa XT25 tweeter
                                                            HiVi M8a mid-range
                                                            Dayton 15" IB woofer

                                                            Question? Does, anyone know how the Dayton 15" IB woofer sounds?




                                                            MI-II-CENTS
                                                            ______________
                                                            The TailWind Generation I

                                                            Comment

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