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another not-quite-voxel subwoofer, but this time with a filter bypass switch....

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  • another not-quite-voxel subwoofer, but this time with a filter bypass switch....

    I made a set of Quarks with a not-quite-voxel subwoofer recently:
    http://techtalk.parts-express.com/fo...oxel-subwoofer

    it is the PE knockdown 0.23 cubic foot box with a 1.5" ID x 12" long port (with elbow)

    This was my modeling:


    The subwoofer had too much mid-bass because the Dayton PE 2.1 bluetooth amp has too high of an active XO point. So I put in a passive filter from PE to attempt to roll off the freq above 100 Hz.

    Chris Roemer was kind enough to point out that using my box and the TB W5-1138 driver and the off-the-shelf PE filter, that I wasn't getting exactly what I thought:
    Originally posted by Chris Roemer View Post
    That LP filter (9.1mH / 280uF) doesn't affect much below 30Hz, but . . .
    It drops that W5 in YOUR tuned box about -2dB @ 40Hz.
    Close to no effect @ 50.
    @ 60 +1dB
    @ 70-80 +3 to +4dB
    @ 100, +/-0
    @ 200 -12dB - (that's the filter's transfer function)

    So, it actually doesn't do a bad job at rolling the sub's highs off passively.
    The response you end up with peaks around 70Hz.
    F3s are near 60 & 90Hz.
    F6s are near 50 & 110Hz.
    F10s near 40 & 130Hz.
    So I decided to build another 2.1 set using Quarks and the same TB W5-1138 in the same 0.23 cu ft KD box
    but this time using a switch to bypass the low pass filter if I wanted to. This also makes a with-vs-without comparison as easy as flipping the switch


    and here's the switch above the input terminals


    here's the final system:
    Click image for larger version

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    Well? the verdict is that is sounds better to me WITH the low pass filter in place. Though the simulation by Chris R says that it will be peaky around 70 Hz, it sounds better than without it.
    Also in terms of low freq extension, I used a sound generator app and it seems to play 40 Hz equally with or without the low pass filter.
    Attached Files
    subwoofer modeling switch to bypass the passive filter wiring of the bypass switch to the passive filter
    Last edited by ceiol; 03-01-2018, 11:16 PM.

  • #2
    oh yeah, I also painted the cone of the TB W5-1138 silver in order to match the Quarks. I think it makes the whole set more visually cohesive.
    Plus the minimal extra weight of the silver paint shouldn't have a significant effect on the performance of the W5-1138

    Comment


    • #3
      Here is the response of the W5-1138 (using measured parameters from my sample) in your 0.23 cu. ft. box (adjusted down for driver and port displacement) with a 1.5" x 12" port (a 57 hz tuning) and your 100 hz low pass filter. You get a peak just under 66hz and an f3 just under 50hz.
      Click image for larger version

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      -Bob
      -Bob

      The PEDS 2.1 mini system
      My A7 Project - another small desktop speaker
      The B3 Hybrid Dipole - thread incomplete and outdated

      Comment


      • #4
        Here is the response of the W5-1138 (using measured parameters from my sample) in your 0.23 cu. ft. box (adjusted down for driver and port displacement) with a 1.5" x 12" port (a 57 hz tuning) and your 100 hz low pass filter. You get a peak just under 66hz and an f3 just under 50hz.


        -Bob
        -Bob

        The PEDS 2.1 mini system
        My A7 Project - another small desktop speaker
        The B3 Hybrid Dipole - thread incomplete and outdated

        Comment


        • #5
          Thanks Bob in GA.

          How come my predicted response via the WB&CD excel sheet looks so different?

          I used the published TS parameters for the W5-1138 from the PE page

          Comment


          • #6
            when I use WinISD, I get this

            Click image for larger version

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            Attached Files

            Comment


            • #7
              Originally posted by BOBinGA View Post
              Here is the response of the W5-1138 (using measured parameters from my sample) in your 0.23 cu. ft. box (adjusted down for driver and port displacement) with a 1.5" x 12" port (a 57 hz tuning) and your 100 hz low pass filter. You get a peak just under 66hz and an f3 just under 50hz.


              -Bob

              Excuse my ignorance since I'm a novice who is just trying to learn....

              but when you say that a 0.22 cubic foot box with a 1.5" inside diameter x 12" long port is a 57 Hz tuning, I don't understand how you came up with this.

              When I use any of the calculators for port tuning, a 0.22 cubic foot box using a 1.5" inside diameter port tunes to 57 Hz when the port length is only 5.5"
              The same box with the same 1.5" ID tubing will tune the box to about 41 Hz if the tube length is about 12"

              (BTW, I have built the PEDS 2.1 system that you designed and I really like it!)

              Comment


              • #8
                MY WinISD agrees w/YOUR tuning synopsis, not BOB's.

                Comment


                • #9
                  I apologize if I fat fingered something. Let me double check.
                  ​-Bob
                  -Bob

                  The PEDS 2.1 mini system
                  My A7 Project - another small desktop speaker
                  The B3 Hybrid Dipole - thread incomplete and outdated

                  Comment


                  • #10
                    My bad. I had 2 ports - not one. I guess I left it set for two from a previous attempt. Disregard. Switching to 1 port, I get much closer to your response now.
                    Click image for larger version

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                    -Bob
                    -Bob

                    The PEDS 2.1 mini system
                    My A7 Project - another small desktop speaker
                    The B3 Hybrid Dipole - thread incomplete and outdated

                    Comment


                    • #11
                      Hi Ceiol,
                      ​I was in a hurry when I replied yesterday to correct my mistake. I just noticed that you built my PEDS, too. Thank you. I would be interested in your comparison of the two systems - PEDS vs. Quark/Voxel. I have only heard the Quarks (without Voxel) for about five minutes and noticed that they did play deeper. I expected that since the Quarks are ported and PEDS are not. Any other major differences you can hear once you add the subwoofers to both systems?

                      ​The small differences in your predicted response and what posted last are most likely because I used the actual DATS2 measured parameters of the W5-1138 that I have. I put mine in a Denovo .23 box but Instead of a port, I found a closeout MCM sub amp that is basically the same as the PE 2.1 amp except the MCM amp has a 6 db bass boost on permanently at 45hz and does not have the 2 channel amp built in.
                      I really like those little Tang Band subs. My next project uses the W3-2108 3" sub. I have it reaching below 40 hz in a box half the size of the Voxel, but obviously it can't play as loud.
                      Thanks
                      -Bob
                      -Bob

                      The PEDS 2.1 mini system
                      My A7 Project - another small desktop speaker
                      The B3 Hybrid Dipole - thread incomplete and outdated

                      Comment


                      • #12
                        Hi Bob,

                        I made your PEDS 2.1 system last year. My son uses it for his computer system and it's great.

                        Your sub is certainly more powerful -- you have the W6 vs the W5 in my not-quite-voxel. And yours is sealed so no port noise even at high volumes. I also think that the sealed subs, helped with an amp bass boost, actually are more musical and accurate than the ported subs.

                        So in a head-to-head comparison, the W6 sub from the PEDS systems sounds better, but it requires an amp with bass boost.

                        For the satellites, it's really hard to beat the Quarks from 100 Hz up. There is a naturalness, a smoothness, a clarity, that I like better than other similar satellites in the same 0.04 cubic foot boxes (Heliums, Bantams, your PEDS satellites). If you're using them as full-range speakers (and not part of a 2.1 system), then the Heliums and Bantams come out on top.

                        Comparing the PEDS satellites to the Quarks, I'll give the edge to the Quarks. Just a little better -- maybe it's the ND20FA-6 tweeter vs the ND16FA-6, or the woofer. Not sure, but both are winners.

                        Certainly, the most compact enclosure that I've ever seen the W6 in is the PEDS subwoofer. I just wish that Dayton 2.1 plate amp had bluetooth!

                        Comment


                        • #13
                          Thanks Ceiol. Its good to know that I was not too far from the best. I haven't had any feedback on them until now. I just wish I had your woodworking skills.
                          ​-Bob
                          -Bob

                          The PEDS 2.1 mini system
                          My A7 Project - another small desktop speaker
                          The B3 Hybrid Dipole - thread incomplete and outdated

                          Comment


                          • #14
                            Originally posted by BOBinGA View Post
                            Thanks Ceiol. Its good to know that I was not too far from the best. I haven't had any feedback on them until now. I just wish I had your woodworking skills.
                            ​-Bob
                            You're too kind -- I'm a total newbie woodworker!

                            I just bought a used router off craigslist a couple of months ago. I'm using the PE knock-down boxes so that makes it easy. Then I just route the holes and flush-mount countersinks. The new skill that I'm learning is the veneering. Mostly I started using TomZ's videos on youtube. Just today I did a darn-near perfect seam using TomZ's method.

                            Veneer is done bottom, then back, then wrap from side to front to side, then finally the top. All to minimize seams. I sand lightly and then just coat with Shellac for the grey set shown above.

                            I want to try the Boiled Linseed Oil, Zinsser seal, then Shellac finish like TomZ's Toni Table Radio
                            Last edited by ceiol; 03-03-2018, 08:49 PM.

                            Comment


                            • #15
                              [QUOTE=ceiol;n1367663]
                              You're too kind -- I'm a total newbie woodworker!

                              I just bought a used router off craigslist a couple of months ago. I'm using the PE knock-down boxes so that makes it easy. Then I just route the holes and flush-mount countersinks. The new skill that I'm learning is the veneering. Mostly I started using TomZ's videos on youtube. Just today I did a darn-near perfect seam using TomZ's method.

                              Veneer is done bottom, then back, then wrap from side to front to side, then finally the top. All to minimize seams. I sand lightly and then just coat with Shellac for the grey set shown above.

                              I want to try the Boiled Linseed Oil, Zinsser seal, then Shellac finish like TomZ's Toni Table Radio
                              [\QUOTE]

                              Depending on the veneer, you can get some pretty nice grain "pop" from Tung Oil.
                              There a couple of variations - watco, tung, or danish
                              You can leave the finish as is, or top coat with Poly or spray on shellac

                              After all, "tung" is a blend of BLO (or another oil), poly and thinner


                              I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                              "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                              High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
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