A New Design Study in progress...

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  • Evil Twin
    Super Senior Member
    • Nov 2004
    • 1531

    A New Design Study in progress...

    There is no question that these are very disturbing times, yet, that just makes it more essential to continue some planned design studies based on newly available products and, let us just say, popular older concepts.


    There is considerable chatter about the new Epique woofers, and even some detailed test data for the E150HE-44, but there are many open opportunities for system builds yet...


    A common issues with the current crop of long throw small diameter "subwoofer" drivers is the difficulty of creating a small optimum design, considering that the T/S parameters largely dictate using a Helmholtz alignment of some type to get extended low frequencies without EQ, but the box sizes and port air velocities render conventional ported approaches essentially unusable, unless the esthetics of a pot bellied stove are appealing to yourself and your significant other...

    Which leaves consideration of passive radiators as another possibility...

    The RSS265PR suggested by Jonmarsh certainly provides adequate performance, but is not conducive to flexibility in enclosure sizing.

    Another interesting if obscure alternative is the Wavecor PR223BD02. Two of many possibilities are shown below...

    Relatively maximally flat, in a 20L enclosure...


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    A tapered extended response alignment, in a smaller 15L net enclosure...


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    Of course, this is only a start, and leaves unanswered many questions about a possible system confirmation. note, that while the upper range is reasonably smooth and HD2 is low, I would not consider this a good candidate for a conventional two way... though with a waveguide loaded tweeter, that could change.

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    DFAL
    Dark Force Acoustic Labs

    A wholly owned subsidiary of Palpatine Heavy Industries
  • Bear
    Super Senior Member
    • Dec 2008
    • 1038

    #2
    I'm a fan of the look of that 15L enclosure, not the least being that I would expect the step response on the 15L cabinet would experience less over/undershoot and have a faster effective settle time.
    Welcome to Rivendell, Mr. Anderson.

    Comment

    • Evil Twin
      Super Senior Member
      • Nov 2004
      • 1531

      #3
      PR history...

      That is a reasonable assumption- it more closely approximates a ported QB3 alignment.

      But the topic of passive radiators and step behavior is an interesting topic, and one not well explored- certainly Unibox is useful in being able to make some estimation of the tradeoffs.


      In my own case, exposure to an early commercial passive radiator system created a very negative impression. This system was the Electrovoice Interface, the original version. This system was a two way with passive radiator and an inline EQ box with HF contour control and a fixed boost and filter for the PR, based on some recently popularized approaches in the AES journal publications regarding tradeoffs in passive radiator systems involving EQ to compensate for acoustic parameters (I.E., small enclosure).

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      At that time I had an early interest in Jazz-Fusion recordings by artists like Mahavishnu Orchestra and Stanley Clarke's solo efforts. The original version of "Eternity's Breath" on "Visions of the Emerald Beyond" had a soft double bass drum roll in the opening bars of music... the transient definition of the EV Interface speaker was such that it converted the percussive double bass drum roll into what sounded more like low organ note. Other music was affected in similar, though not as obvious, ways.

      Stanley Clarke's "School Days" lost part of it's percussive snap in the lower registers- this was all well before CD's, and sadly, the CD version of the "School Days" album was compressed in dynamic and frequency range- only the version on the Stanley Clarke "Bass-ic Collection" comes close to the original vinyl.

      For many years, I was not at all interested in passive radiator systems, though I suppose you would not say that this is what scarred me for life!

      My opinion about passive radiators turned around upon hearing the Akira Tidal in Munich, and of course that experience inspired the Kurosawa Dai Katanna, and a fair amount of investigation into their use and finding flexible and usable drivers, as documented elsewhere on the forum.

      But regardless of modeling synthesis and paper advantages, the key factor must be the audible results.

      While the Kurosawa project has been in storage many years now in the outer rim (though being retrieved this very week), the Ardent D was an opportunity to put the concepts to a more immediate test. Though it was based on the Vimberg Mino design, unlike the Mino, which is conventionally ported, the Ardent D was developed from the ground up with the use of PR's in mind, and a model which has been used extensively in system calculations, the RSS265PR. Being a smaller system with relatively small woofers, the intent was not to extend response to well below 30Hz, but to optimize the behavior in the pop and rock and roll part of the spectrum. Tuning is easily adjustable with this PR, having a full set of weights supplied, so converted to an EBS alignment if desired is straightforward. Other passive radiator manufacturers would do well to take note...

      This was the initial low frequency alignment target:


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      Measurements established that the actual Fb was lower, at about 28Hz, as one additional disk was added to the PR configuration. In room measurements showed an F3 of approximately 30Hz.

      Listening evaluations were conducted with a variety of material, though the largest part was fusion Jazz and jazz/R&B; A variety of program material was auditioned using the stored FLAC files and the VOX player- this included a high definition SACD rip of Gaia, by James Taylor, "What I am" by Edie Brickell, "East River Blue" by Spyro Gyra, "Ectopia" by Oregon, "Rich Woman" by Allison Kraus and Robert Plant, "The Lighthouse Tale" by Nickel Creek from an SACD HD rip, "Gaucho" from an HD SACD rip, "No one is to blame" by Howard Jones, the live version of "Chrale No. 1 "Sleeper" by the Jacque Loussier Trio, "Against the Wind" by Marie Brennan, "Dark Alan" by Karen Matheson from Rob Roy, several Poor Claires cuts, "Chant" by Fourplay, "Corner Pocket" by Harry James & His Big Band, and "Spiral" by Hiromi.

      The most interesting impression was how neutral sounding the experience was, but particularly how the pitch definition in the low frequency instruments (such as standup bass, bass guitar) did not seem to have a specific warmth or range emphasis, but rather was very revealing of pitch definition and clarity up and down the scale. This was very evident even in pop pieces like Gaia, where the percussion break at the final verse break was reproduced very evenly but with increasing power as the pitch of the drums struck were lower and lower. No bloat, but high impact. This is not an attribute commonly attested to for reflex systems, and it's possible/likely that part of the reason for this character was the behavior and quality of the Accuton AS168.

      This is inline with the character of what I heard with the Tidal Akira, (which used the Accuton AS190) and why I was inspired to see how much of that could be captured in a DIY configuration at a somewhat lower price point.


      Getting back to the E180HE-44, the plots shared above are just a couple of examples of what is possible, including a relatively undersized enclosure with EBS style tuning, and a more optimum size with near maximally flat tuning. Those parameters could be reversed, of course, if desired. In a larger system using multiples of the E180HE-44, one might prefer to use the smaller volume per driver to minimize the total system size, and this could be done without too much drawback- however, my various "what ifs" indicate that around 20-24L net is likely the sweet spot. I have some test boxes in preparation which will hit the upper end of this target. Another supply of passive radiators is being secured.

      My evaluations of the E180HE indicate that it is not well suited to a two way system, but I believe there may be interesting ways to use it with other drivers that fall short of the expense of a conventional full blow three way. It remains to be seen if that intuition will pan out, but preliminary POC synthesis evaluations are promising...

      The gating item is completion of the outer Rim facility and moving supplies and equipment in place, which is underway as I write...
      DFAL
      Dark Force Acoustic Labs

      A wholly owned subsidiary of Palpatine Heavy Industries

      Comment

      • technodanvan
        Senior Member
        • Nov 2009
        • 998

        #4
        All this E180HE-44 talk still has me rethinking my decision. All PRs necessary for the project have been acquired (I have certainly contributed to their relative scarcity) and based on modeling can be used whether I go with the Epique or the alternative. My spouse indicated the Epique would look better in an all-black cabinet as well, and we all know the dark lord's favorite color palette...

        Perhaps the next 10% off deal at PE will be enough to push me over the edge.
        - Danny

        Comment

        • tktran
          Senior Member
          • Jan 2005
          • 658

          #5
          In the first post, in harmonic distortion- the light dashed line is H3, is that correct? If that's the case it's disappointing that the midrange has more H3 than H2 (200Hz to 1Khz).

          In that case, I too, would preclude the use of it in a 2way, despite the amplitude response being very managable.

          Comment

          • Evil Twin
            Super Senior Member
            • Nov 2004
            • 1531

            #6
            Originally posted by tktran
            In the first post, in harmonic distortion- the light dashed line is H3, is that correct? If that's the case it's disappointing that the midrange has more H3 than H2 (200Hz to 1Khz).

            In that case, I too, would preclude the use of it in a 2way, despite the amplitude response being very managable.
            Exactly. And this is in spite of the motor and suspension linearity- there is a factor I believe with inductivity modulation to be considered. And you can tell from the shape of the curve that there seems to be some resonance amplification at work, though it doesn't make sense on the surface that it should mimic the amplitude response but at 1/10th of the frequency.

            This does merit further investigation- which is why this post is called a Design Study. I do have a target system concept and drivers, but have little time to spare in the immediate future pending the logistical work in progress.
            DFAL
            Dark Force Acoustic Labs

            A wholly owned subsidiary of Palpatine Heavy Industries

            Comment

            • tktran
              Senior Member
              • Jan 2005
              • 658

              #7
              I went back and looked the PE datasheet and it does look like the trends are there as well. It's hard to detect at a glance because the scale is stretched horizontally and compressed vertically (SPL range of 120dB).

              The datasheet doesn't have a legend, but it's clear now that red is H2 and purple is H3, blue is THD which is obviously dominated by H2 and H3. Between ~150Hz and ~800Hz H3 is higher than H2.

              Lars Risbo recently published a document re: series notch filters as the final leg prior to the driver, for reduction of harmonic distortion related to resonances.
              If this description sounds like gibberish, it's my fault, not Lars.

              Have a look- it may be of some interest to you.

              titled

              March 30 2022
              "Low Distortion Filter for PTT6.5X04-NAA"




              It can be used for other drivers with distortion related to resonances, I believe eg. Dayton RS, SEAS W/L series metal cone drivers
              Not sure whether it would help in this case, because the H3 is not directly 1/3rd the frequency of the amplitude response...

              Comment

              • JonMarsh
                Mad Max Moderator
                • Aug 2000
                • 15261

                #8
                Originally posted by technodanvan
                All this E180HE-44 talk still has me rethinking my decision. All PRs necessary for the project have been acquired (I have certainly contributed to their relative scarcity) and based on modeling can be used whether I go with the Epique or the alternative. My spouse indicated the Epique would look better in an all-black cabinet as well, and we all know the dark lord's favorite color palette...

                Perhaps the next 10% off deal at PE will be enough to push me over the edge.
                What kind of project do you have in mind now, Danny?
                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

                • Evil Twin
                  Super Senior Member
                  • Nov 2004
                  • 1531

                  #9
                  Originally posted by tktran
                  I went back and looked the PE datasheet and it does look like the trends are there as well. It's hard to detect at a glance because the scale is stretched horizontally and compressed vertically (SPL range of 120dB).

                  The datasheet doesn't have a legend, but it's clear now that red is H2 and purple is H3, blue is THD which is obviously dominated by H2 and H3. Between ~150Hz and ~800Hz H3 is higher than H2.

                  Lars Risbo recently published a document re: series notch filters as the final leg prior to the driver, for reduction of harmonic distortion related to resonances.
                  If this description sounds like gibberish, it's my fault, not Lars.

                  Have a look- it may be of some interest to you.

                  titled

                  March 30 2022
                  "Low Distortion Filter for PTT6.5X04-NAA"




                  It can be used for other drivers with distortion related to resonances, I believe eg. Dayton RS, SEAS W/L series metal cone drivers
                  Not sure whether it would help in this case, because the H3 is not directly 1/3rd the frequency of the amplitude response...
                  Thanks for the link, though I have read it already. PuriFi is to be commended for the degree to which they are willing to share technical knowledge.

                  I have been doing this for many years, starting with the Modula and Natalie P designs... not necessarily pointing it out, but it's a habit for woofers, midrange, and tweeters, and the efficacy is indisputable.
                  DFAL
                  Dark Force Acoustic Labs

                  A wholly owned subsidiary of Palpatine Heavy Industries

                  Comment

                  • augerpro
                    Super Senior Member
                    • Aug 2006
                    • 1866

                    #10
                    Maybe Jon can interpret Lars' answer to me. I take it as "no" but I don't quite understand the mechanism he's describing.

                    augerpro said:
                    I have a question: I've often used a small .2-.3 uF cap in parallel with the first inductor in a woofer circuit to notch the woofer breakup in the 5-10khz area. This should work as well? It's a series notch, so high impedance at that frequency, does it matter that it is the first filter in the circuit? Must it always be the last?

                    Lars response:
                    if the coil with the small cap across is not last then the driver does not see the high load impedance caused by the LC tank. However, you would also normally like to have a cap to ground after the L to get a 2nd order electrical filter. This is why Kim (app not author) made the separate notch coming after the first usual series L with a C to ground. Then you both get the roll off and a load impedance peak at the notch frequency.
                    ~Brandon 8O
                    Please donate to my Waveguides for CNC and 3D Printing Project!!
                    Please donate to my Monster Box Construction Methods Project!!
                    DriverVault
                    Soma Sonus

                    Comment

                    • technodanvan
                      Senior Member
                      • Nov 2009
                      • 998

                      #11
                      Originally posted by JonMarsh
                      What kind of project do you have in mind now, Danny?
                      Same one we briefly discussed via email: ~100L, 4x E180HE-44s, 4x RSS265PRs and a King Coax. I'm just about sold on the idea of switching from the Anarchy's, I just need concurrence from my wallet on the remaining bits and baubles (the three coaxials and a dozen PRs are on hand...but I only have two Epiques of the correct size). The cabinet design I want to employ uses a moderately complex bit of bracing that I may need a CNC for as well. I might have to wait for Steve to get back up to speed for that, assuming I can get on his waiting list.
                      Last edited by technodanvan; 02 April 2022, 12:39 Saturday.
                      - Danny

                      Comment

                      • technodanvan
                        Senior Member
                        • Nov 2009
                        • 998

                        #12
                        I pulled the trigger. A total of 12 Epiques will be in stock on my shelf...as soon as they aren't backordered. Well, 14 if you count the little ones.

                        I'm still thinking about a project for the Anarchy's I have on hand and may have settled on a somewhat higher value version of the same speaker using the King Coax's little brother, the Seas MR18REX, and porting the speaker instead of using passive radiators. Could make for some beastly surrounds.
                        - Danny

                        Comment

                        • JonMarsh
                          Mad Max Moderator
                          • Aug 2000
                          • 15261

                          #13
                          Sounds like some stuff to keep you busy for quite a while! And generally, that's fun and a good thing!
                          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

                          • Evil Twin
                            Super Senior Member
                            • Nov 2004
                            • 1531

                            #14
                            Originally posted by technodanvan
                            Same one we briefly discussed via email: ~100L, 4x E180HE-44s, 4x RSS265PRs and a King Coax. I'm just about sold on the idea of switching from the Anarchy's, I just need concurrence from my wallet on the remaining bits and baubles (the three coaxials and a dozen PRs are on hand...but I only have two Epiques of the correct size). The cabinet design I want to employ uses a moderately complex bit of bracing that I may need a CNC for as well. I might have to wait for Steve to get back up to speed for that, assuming I can get on his waiting list.
                            I, too, have more of the E180HE-44 on backorder, for "any day now" shipment. This status has been continuing for a surprising amount of time, but considering the manufacturing source, and world events, perhaps one must expect these delays.

                            On the other hand, another pair of 6ND430s for the test build have arrived and been processed through initial QA.


                            Impedance curves look very clean and flat, as expected with this Neo motor.


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                            As an interesting aside, and comment on the selection of this pro class driver as a midrange candidate, consider how similar the cone construction is between the 6ND430 and the PuriFi midrange...


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                            I leave it to the reader to recall the upper range behavior of both drivers approaching the breakup point...

                            There is some reasonable logic to suggesting that the Eighteen Sound 6ND430 is in some senses a budget competitor to the very excellent PuriFi part. But I did not say that...
                            DFAL
                            Dark Force Acoustic Labs

                            A wholly owned subsidiary of Palpatine Heavy Industries

                            Comment

                            • tktran
                              Senior Member
                              • Jan 2005
                              • 658

                              #15
                              Ooh I’ve been itching to buy that unit. By the impedance trace,
                              my guess is that is the 8 ohm model?

                              Ever since Zach measured it a decade ago, as well the B&W midrange; it occurred to me that the suspension/soft parts design is critically important. The limited availability in Australia… we’ll, It’s sitting in my German online cart.

                              I suspect there’s some mild resonances between 700-1Khz, but dispersion probably usable to about 1.6Khz. (I aim for no more than +/- 2dB @ 45 degrees)

                              Comment

                              • Evil Twin
                                Super Senior Member
                                • Nov 2004
                                • 1531

                                #16
                                Depending on your expectations and intended crossover slope, 1600Hz may be more conservative than necessary...

                                And as always, data is more useful than speculation. 10 degree increments, out to 50 degrees.


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                                Sourcing can be a problem depending on local activities in this sector- in the United States, there are several sources I have used, this last one, in the service of speed, was Beach Audio through Amazon.
                                DFAL
                                Dark Force Acoustic Labs

                                A wholly owned subsidiary of Palpatine Heavy Industries

                                Comment

                                • gbegland
                                  Senior Member
                                  • Apr 2005
                                  • 233

                                  #17
                                  Back when I built my open baffles, had the BG Neo10 not become available to DIY, the 6ND430 was my choice for mid out of all the candidates I had tested. It's a nice sounding driver for sure. As a matter of fact, I had the extra 6ND430 I needed in my cart to order and then somewhere on a forum I read the Neo10 could be purchased and I immediately bought 4 of them instead and never looked back.

                                  Greg

                                  Comment

                                  • Evil Twin
                                    Super Senior Member
                                    • Nov 2004
                                    • 1531

                                    #18
                                    The Neo 10 is a fine driver, though about twice the price of the 6ND430; but is not as well suited to the planned system configuration- and regardless, it's not available anymore through the normal sources in the US. Many components are becoming unobtanium as of late... narrowing the private constructor's choice considerably.
                                    DFAL
                                    Dark Force Acoustic Labs

                                    A wholly owned subsidiary of Palpatine Heavy Industries

                                    Comment

                                    • Scottg
                                      Senior Member
                                      • Nov 2006
                                      • 335

                                      #19
                                      Yeah, unfortunately it's just the GRS PT5010-8 (Neo-10 clone) - and that doesn't have very good non-linear performance (..in fact the higher order spectra is pretty bad).

                                      I think it's an assembly problem for the GRS PT5010-8.

                                      Even though there is another recent thread devoted to the new GRS ribbons, I thought I would start this new thread that compares the frequency response and distortion for the following: GRS PT2522-4 (Neo3 copy) B&G Neo3PDRW Radian LM8K Unbranded Asian copy of Neo8 GRS PT5010-8 (Neo10 copy)...


                                      Note however that these measurements are without a baffle (..and I don't think it was a "dual-channel" measurement).

                                      Comment

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