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3way active, HiVi,Dynavox,AC, labyrinth enclosure

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  • 3way active, HiVi,Dynavox,AC, labyrinth enclosure

    It's time. I go to my friend's place a lot, but he lacks tower speakers, so it's time to build.
    Right + Left floor standing tower, supplemented by subwoofer.
    I already own the Selah Audio 3 way dipole, so I'll borrow some of Rick's ideas, and expand upon them. I already own a Rane AC23 active crossover, which we modified by replacing the op amps with TL052 and TL054, so we'll be tri-amping with a 6 channel 120 w/channel amp, that happens to be lying around. I've done some reading about Mr. Linkwitz Orion system, and actually built his original system from the 70's from scratch, and also build a sewer pipe subwoofer, so this is not totally new.

    So the bass is handled by a subwoofer, I already built the HiVi D10.8 x 2 transmission line "sewer pipe" subwoofer. The sewer pipe t-line subwoofer is totally amazing - my kids cannot believe how well it reproduces the slam of the kick drum, and the organ pedal notes. Highly musical, extremely clear, with no hint of boominess.
    The "regular" bass will be HiVi D10.8 x2, per side. I've already used this driver for the sub, and it is excellent. I've also used the D8.8 and the D5.8, and these are all excellent drivers. So I'm totally confident with this choice. This will be a sealed enclosure, made from 3/4" baltic birch, 4 feet high cabinets, 16" wide x 16 deep. This volume should result in a 3 db point of 38 - 40hz, and running the HiVi in parallel means we have about 200w/channel available to drive them.
    Above this, sits the MTM. At first I was thinking regular dipole, maybe H frame, maybe open back cab, but my friend doesn't have the room to position the enclosure 3-4 feet from the wall, which you need for proper dipole effect. The it occured to me: I can time delay the rear wave, instead of by speaker placement, instead build a labyrinth. For instance, a 2 feet tall box, with 3 partitions, will force the rear wave to travel about 6 feet, before it can exit through a large port in the rear of the enclosure.
    Since the plywood comes in 4x8 sheets, it is handy to make this box 24" tall, by 11" wide, by 16" deep - about 1.6 cubic feet of volume. With 3 x 20" partitions, and a large port in the bottom half of the back panel, results in a time delay of about 6 msec. This time delayed rear wave will have the effect of a dipole, placed 5-6 feet from the rear wall of the room - or at least according to my "theory".
    So, now comes choice of driver for the midrange, and looking through the "menu" of what is sold, and checking my budget, I think the
    Dynavox LW6004PMR is a superb choice. At a little over 80$ per driver, it looks superb for this "high end" attempt, without breaking the bank, because it has extremely low distortion figures, very flat impedance graph, and very smooth output. Again, running two of them, per side, in parallel, means another 200w/channel can be used to drive them, because the Parasound 1206 is a high current design.

    In between the two Dynavox 6 1/2 inch midrange woofer, will sit the very nice and highly rated Aurum Cantus G2S1, that puts out 96db per 1 watt.

    Electronic crossover, 24db/octave, at 200hz and 2200 hz, will give a nice optimum split of acoustic power: 60% to the HiVi, these huge 12 inchers will love it, 25% to the Dynavox, so the chances of clipping the signal here is very little, and the 2.5mm excursion of the Dynavox is plenty in this band, and 15% to the ribbon tweeter, which will only handle 45 watt peaks, so we will protect it nicely with the 24db crossover (in addition to a capacitor in series, of course). The ribbon tweeter should put out 110db peaks, and the HiVi and Dynavox should also be capable of 115 db or so each as well, so the combined might, of these, including the sub, means sound pressure levels equal to being at a live rock concert. But more clean.

    So, a very unusual setup: sealed box for the bass, the t-line labyrinth midrange, and MTM. I've not heard of people using t-line like this, but I'm hoping to get a simulated planar effect by going this route.

    Good - or bad?

  • #2
    Re: 3way active, HiVi,Dynavox,AC, labyrinth enclosure

    So, I've decided to use the T-line configuration for the 2 x Hivi D10.8 The folded T-line should be about 7 feet long. this should drop the resonant frequency of the system, and result in increased bass performance. I am half way through building the cabs, so I will be able to take pics and post pics.
    Also, i plan to measure the resonant frequency, impedance vs frequency, response vs. frequency, etc.

    Comment


    • #3
      Re: 3way active, HiVi,Dynavox,AC, labyrinth enclosure

      I'd use the Dynavox LW5004 as a mid over the 6.5". It has not breakup, and can run smoother and higher.

      Later,
      Wolf
      "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
      "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
      "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
      "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

      *InDIYana event website*

      Photobucket pages:
      http://photobucket.com/Wolf-Speakers_and_more

      My blog/writeups/thoughts here at PE:
      http://techtalk.parts-express.com/blog.php?u=4102

      Comment


      • #4
        Re: 3way active, HiVi,Dynavox,AC, labyrinth enclosure

        So I finally completed the cab for the D10.8. The 7 foot t-line was too short, and there was a strong resonance at 40, so I increased the line length to about 15 feet, and now used only one driver. This tunes the line to 16 hz, so there is no more nasty resonance. You need to do special modeling for this kind of t-line, and the cab would be too large if I used 2 x D10.8, according to the alignment tables, so the cab now has just one D10.8, which is a pretty big driver anyways . so far, so good.

        Comment


        • #5
          Re: 3way active, HiVi,Dynavox,AC, labyrinth enclosure

          Actually, if you want predictably good results, you need to do "special" modeling for any T-line. Alignment tables might get you close, but unless you model it, you're really guessing a lot. As to your first attempt with the 7-foot line, assuming it wasn't tapered, its 1/4-wave resonant frequency would have been right at 40 Hz. Maybe the reason you didn't like what your heard is that it was not the optimum resonant frequency for your drivers? Lowering the 1/4-wave resonant frequency by ~doubling the line's length may also not be a good choice, even though you liked the sound better. There are several people that frequent this forum that are quite capable of modeling a TL for you, me included, and would be happy to help if asked. Reasonably accurate T/S values for your woofers would be required, of course.
          Paul

          Originally posted by object16 View Post
          So I finally completed the cab for the D10.8. The 7 foot t-line was too short, and there was a strong resonance at 40, so I increased the line length to about 15 feet, and now used only one driver. This tunes the line to 16 hz, so there is no more nasty resonance. You need to do special modeling for this kind of t-line, and the cab would be too large if I used 2 x D10.8, according to the alignment tables, so the cab now has just one D10.8, which is a pretty big driver anyways . so far, so good.

          Comment


          • #6
            Re: 3way active, HiVi,Dynavox,AC, labyrinth enclosure

            T-line modeling was done on quarter-wave.com and yielded results! My cab design was all wrong, and even my sewer-pipe subwoofer will have to be rebuilt, using the new CADD designed t-line, which works out to a 34" x 18" x 14" cab, will hold all the 5 drivers, and have a 95" tapered t-line. I built a smaller cab for a pair of D8.8 using the CADD modeling, and it worked really well!!! - so I am totally convinced.

            I highly recommend everyone head over to the fabulous quarter-wave.com website, posted by the master of the t-line, Martin J King.

            Comment


            • #7
              Re: 3way active, HiVi,Dynavox,AC, labyrinth enclosure

              http://s1127.photobucket.com/albums/...20the%20D10_8/

              Please check out the photo of the completed project. Thanks to all your help, the final result is AWESOME!!!
              Woofer: HiVi D10.8 in a quarter-wave.com MathCAD 32" x 14.5" x 17.5" enclosure, 96" folded t-line. The performance is just like a subwoofer. ... the midrange is in a sealed compartment in the same cab, stuffed with wool -
              Midrange: Tang Band W4-1320SJ 4" Bamboo Cone Driver x 2 crossed at 250, 2500 at 24 db/octave, this full range driver has moving mass of 3.5 Grams! so the evaluations of fabulous are right on! Using this phenomenal full-range driver as a mid-range really lets it sing - vocals cause goose-bumps.
              And tweeter, I only have a small spot in this cab, so I went with the SB Acoustics SB29RDCN, a fabulous tweeter, especially when crossed at 2500, 24db/octave.

              Obviously this is tri-amped, using the easy to obtain and cheap Rane AC22, which has been modded with modern op-amps (very easy to do).

              My wife comments of the stunning realistic sound quality, totally warm and smooth easy on the ears type of sound, that can be also cranked very high with no evidence of any distortion at all, and sounds identical to being in the recording studio (far superior to concert venue).
              She also like the nice way the cab has been finished with oak veneer, and also that the cab is a reasonable size. Despite this relatively small size for a t-line, there is NO COMPROMISE in the bass modeling, this is an "all-in" design.

              I made a left and right channel as shown in photo, and then a third cab as a subwoofer, using the Aurasound 12" NRT subwoofer. This third cab is just about the identical size, just one inch deeper, to allow for perfect modeling.

              The final product, is the same as having 3 subwoofers! because the HiVi D10.8 has subwoofer performance in this type of cab. Even though the Tang-Band drivers are side to side, the truncated frame allows very close spacing so I cannot hear any "lobe" artefacts. Actually all 4 drivers are packed together as close as you can possibly get them, so this is an "ultimate" "ne plus ultra" type design, in my view. Tri-amping with 100w/channel drivers gives the equivalent of 9x the power per side, due to Ohm's law and Joule's law, that Power is proportional to Voltage **2, so this is similar to running 900w/side but only requires cheap 100w/channel budget.

              I would appreciate comments, and be glad to answer any questions.

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