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Zaph SR71 Build Thread...

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  • Zaph SR71 Build Thread...

    So after weeks of agonizing over what speakers to build, I finally decided to go smaller and higher-end, and build the Zaph SR71's...

    First things first: huge thanks and round of applause to Zaph for his enormous contributions to the DIY community, including this design. I have spent many hours pouring over his site, and have learned a tremendous amount from doing so.

    Here is a link to Zaph's wonderfully detailed write-up of these speakers:

    http://zaphaudio.com/SR71.html

    So I ordered the "parts only" kit from Madisound... as much as I would have liked to build the crossovers from scratch, it was tough to pass up the 10% discount on all of the parts (including drivers) by buying the kit... I'll still have to solder up the crossovers, so I'll have some fun doing that...



    I'll be building the cabinets from scratch, more or less exactly to Zaph's specs, so they'll look very much like these, only painted... not sure what color yet. The only other changes I'll be making is to make slightly thicker baffles (1.25" instead of 1"), and I'm going to have the drivers be slightly closer together. Doubtful that these theoretical upgrades would make any difference that I'd be able to discern, but what the hey.



    So here we have the top of the cabinet being glued to one of the sides... in my opinion these first clamp-ups are the most crucial... get these nice and square and the rest of the cabinets will come together beautifully... the corner clamps shown here are an absolute godsend for this... sold for about $9 each at home depot... best $18 you'll ever spend... the clamp at the top of the picture is simply holding the assembly to a heavy iron right angle we have lying around the shop, so that I can hang the whole thing off theedge of the table, which makes it much easier to use the second right angle clamp underneath...



    And now the bottom of the cabinet clamped up...



    Here we have 2 layers of MDF (one .75" piece and one .5" piece) clamped up to make nice thick 1.25" baffles. I've made the baffles 1/8" bigger all the way around than the rest of the cabs, to be cleaned up later with a flush router bit. I'll also be routing a substantial chamfer on the back edge of the woofer hole so that the thick baffle doesn't interfere with the woofers...



    Much more to follow...

  • #2
    Re: Zaph SR71 Build Thread...

    Those Madisound crossovers are very nicely constructed, and at a very reasonable price. I'd like to see PE offer the same service. For a big XO, 3-ways and complex 2-ways, their assembly service is a great way to go.

    it's always nice to see a tutorial on construction methods, especially so nicely photographed as yours. I'll be watching closely, as I'm sure the rest will.
    R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
    Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

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    • #3
      Re: Zaph SR71 Build Thread...

      It will be an improvement

      Thickerer boxes are betterer!!! IMO, it makes a lot of difference adding extra bracing and thicker panels and IS audible.

      I have spent the day working out a system to make the Madisound tower cabinets I have tight enough not to make me barf. Don't get me wrong here, they look wonderful and have the great removable baffles, and I am very satisfied with what I paid for. Smaller pre-built cabs are much tighter though.

      So far: one 1.25" hardwood dowel transverse behind the drivers; 6 screws per internal removable bracing panel, the cabinet divider is getting 4 3.5" holes bored through it and being turned into another shelf brace for a total of 3...LOL I hope not to but these tall guys may require permanent baffle attachment. Even though it is vented I don't like any sort of hollow sound from a cabinet.

      My favorite David Weems quote: "With a home-built speaker, you can easily beat any manufacturer in one area - build quality."

      Cheers and Nice Shop / Robert

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      • #4
        Re: Zaph SR71 Build Thread...

        Originally posted by robert View Post
        Thickerer boxes are betterer!!! IMO, it makes a lot of difference adding extra bracing and thicker panels and IS audible.
        Dangit... now why did you have to go and say that? Now you've got me wondering if I should thicken up the other walls as well...

        I suppose it's not too late... I could add another 1/2" layer to the other walls... but it would make the front baffles wider, and I don't want to mess with that.

        You mentioned that you're adding additional bracing to your madisound cabs... are you concerned about how this reduces the internal volume? Does your speaker design compensate for the reduction is the difference in volume negligible?

        It would be easy enough to add more braces to these cabs, but I'm concerned about how the braces will reduce the volume of the port... maybe I'll just figure out how much material I'm removing by adding the chamfers (original design has no chamfers) and then add that much volume in additional bracing.

        I'm probably over-thinking it... I've become a bit obsessed with achieving precisely the same internal volume as Zaph's speakers... possibly to the point of overkill.

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        • #5
          I wouldn't change the front

          I wouldn't change the front of the speaker too much including the driver locations. The crossover was carefuly optimized for the design as it was specified. Any theoretical improvement from a tighter center to center spacing might be outweighed by altered phase and baffle effects do to different driver locations than what the plans call for.

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          • #6
            Re: I wouldn't change the front

            Originally posted by sendler View Post
            I wouldn't change the front of the speaker too much including the driver locations. The crossover was carefuly optimized for the design as it was specified. Any theoretical improvement from a tighter center to center spacing might be outweighed by altered phase and baffle effects do to different driver locations than what the plans call for.
            Hrrmph... are you saying I shouldn't make the baffles thicker either?

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            • #7
              Thicker baffle should be ok

              Thicker should be ok but I would stick to the specified width x height and location of drivers.

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              • #8
                Re: Zaph SR71 Build Thread...

                There it is again...the class 10 cleanroom.

                Lunchroom...where is that?. I think I read in another thread you do this stuff at work (lucky bastard)...where's that shop?

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                • #9
                  Re: Thicker baffle should be ok

                  Originally posted by sendler View Post
                  Thicker should be ok but I would stick to the specified width x height and location of drivers.
                  Ok, I'll do that... I haven't cut the driver holes yet, so no problem.

                  Thanks for the input!

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                  • #10
                    Re: Zaph SR71 Build Thread...

                    Originally posted by tubbsbright View Post
                    There it is again...the class 10 cleanroom.

                    Lunchroom...where is that?. I think I read in another thread you do this stuff at work (lucky bastard)...where's that shop?
                    I'm working in the shop, not the lunchroom... LOL :p

                    I'm the Principal Industrial Designer at a product design and development company called Ximedica here is Providence RI... we have a prototype shop here, complete with a sanding room, milling machined, lathes, spray booth, the works.

                    We actually do have a clean room, but I'm quite literally not allowed in it.

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                    • #11
                      Re: I wouldn't change the front

                      Originally posted by lunchmoney View Post
                      Hrrmph... are you saying I shouldn't make the baffles thicker either?
                      Making the baffle thicker won't hurt anything and will only help make your cabinet less resonant. Also adding 1" width to the overall cabinet is not going to make much difference either. If you are concerned with the stiffness of your cabinets making the walls .5" thicker is fine and is an easy solution to stiffening your cabinet. The slight change in low frequency diffraction is not going to be audible by a 1" change in baffle width.

                      The difference will be less than 1db below around 500Hz. However a resonant cabinet could be very audible. If you are really worried chamfer the 1/2 peices you add on the side and this will slighten any effect they have.
                      Dave

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                      If you are reading it in English thank a Veteran
                      .

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                      • #12
                        Re: I wouldn't change the front

                        Originally posted by dthomas View Post
                        If you are concerned with the stiffness of your cabinets making the walls .5" thicker is fine and is an easy solution to stiffening your cabinet. The slight change in low frequency diffraction is not going to be audible by a 1" change in baffle width.

                        The difference will be less than 1db below around 500Hz. However a resonant cabinet could be very audible. If you are really worried chamfer the 1/2 peices you add on the side and this will slighten any effect they have.
                        I'm actually not that concerned, particularly since I've read nothing but rave reviews on these speakers exactly as spec'd... I suspect I'm just getting carried away.

                        Let's remember that these speakers aren't very big... it's not like this is a big subwoofer.

                        I'm overthinking it. I should just build them as spec'd and be done with it, other than the thicker baffle, which from all I've read is the most important panel to have thicker.

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                        • #13
                          Re: Zaph SR71 Build Thread...

                          I'm sure Zaph will be happy if you do not improve on his design.

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                          • #14
                            Re: Zaph SR71 Build Thread...

                            Originally posted by djg View Post
                            I'm sure Zaph will be happy if you do not improve on his design.
                            Are you suggesting that I'm committing heresy here? I think that's a bit dramatic. We're talking about minor tweaks here.

                            I'm not trying to question his design, and I hope he would take no offense... I didn't mean it that way... I'm sure I'd be absolutely thrilled with the speakers if my cabs were absolutely identical to those pre-made cabs...

                            His design is based on a pre-made cabinet, so he had no freedom to adjust wall thicknesses or driver spacing... I'm just considering what minor improvements I could make since my cabinets are being made from scratch, that's all... that's one of the big advantages of making your own cabinets... it's not just about saving money.

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                            • #15
                              Re: Zaph SR71 Build Thread...

                              I should have put improve in quotes. You do very nice work, and I'm sure you will do a very nice job on these speakers, and give all of us another great build thread.

                              If you read Zaph's site, one of his pet peeves is people who modify his designs and still call it a Zaph design and complain that it sounds crappy. Since you have already started the cabinets, I would not do any mods that would change the baffle width or box volume, but that's me and how I like to follow plans.

                              On the other hand, if you wanted thicker walls and more bracing, you could modify the box by adding to the depth to compensate for volume lost by thicker walls and maintain the same baffle dimensions.

                              That's all I meant. I look forward to viewing your SR71 build thread.

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