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Re-purposing old cabs, 13.5" wide, 1.6 ft3 (46 liters). Any ideas?

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  • Re-purposing old cabs, 13.5" wide, 1.6 ft3 (46 liters). Any ideas?

    In 1979 I built my first pair of loudspeakers from parts I ordered from McGee Radio: 8" Rockwell with a passive radiator and a piezo tweeter. They eventually made their way to Alaska with my best friend, where they are now still in use. Wasilla, outside of Anchorage. He has basic handyman skills, but he's never built loudspeakers, and he's now interested in upgrading them -- using the boxes and putting in new drivers. The cabinets are 13.5" wide, 24" tall, and 12" deep (external dimensions) -- big enough for a classic 3-way. He's in a temporary living situation where his table saw is in storage, but he has access to hand power tools like router, circular saw, etc. Any proven designs come to mind that come close to the critical dimensions of cabinet width, 13.5", and volume, 1.6 cubic feet or 46 liters?

  • #2
    Econowave deluxe? Subwoofers? I've built both with old monkey coffins. There are some classic three ways at troels site, that might work with those dimensions.

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    • #3
      An 8" 2-way ("Classic" drivers) w/a vent should let him enjoy bass down into the 30s w/the wide dispersion of a dome. Pretty nice upgrade (might be able to just modify the old baffle instead of creating a new one - for a 3-way).

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      • #4
        https://web.archive.org/web/20060526...dayton_8MT.htm

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        • #5
          Well, THAT XO is over-complicated (and, frankly, "X-over Pro" kinda sucks as it doesn't even make use of real F/Z data files in its sim).
          If you want to use those drivers though, I just updated an XO I did for them using Dayton's latest data.

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          • #6
            Originally posted by Chris Roemer View Post
            Well, THAT XO is over-complicated (and, frankly, "X-over Pro" kinda sucks as it doesn't even make use of real F/Z data files in its sim).
            If you want to use those drivers though, I just updated an XO I did for them using Dayton's latest data.
            Hey Chris, how does this XO look for that design?

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            • #7
              Close (but those WERE about 10 y.o. F/Z files).
              Using today's data for those drivers:
              HP: drop 9n(ohm) resistor down to 7n, and drop 6.8uF cap down to 4uF.
              LP: make both caps a bit larger: 10 (notch) to 14uF (seems like the breakup freq. has slid down a bit - over time?)
              and 8uF (on Zobel) to 15uF.

              A tad rougher than before, but should still be serviceable.

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              • #8
                Originally posted by Chris Roemer View Post
                Close (but those WERE about 10 y.o. F/Z files).
                Using today's data for those drivers:
                HP: drop 9n(ohm) resistor down to 7n, and drop 6.8uF cap down to 4uF.
                LP: make both caps a bit larger: 10 (notch) to 14uF (seems like the breakup freq. has slid down a bit - over time?)
                and 8uF (on Zobel) to 15uF.

                A tad rougher than before, but should still be serviceable.
                So, let's say I went with those drivers and that crossover… what should the box described above be tuned to (fb)? Ideally, should the volume be reduced at all?

                Thanks to all for your helpful suggestions.

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                • #9
                  Also, at 13.5" wide, will bsc be off?

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                  • #10
                    30Hz. 3"id x 11" should do. You'll lose .05 cf, but 11" will still be good (probably have to use an elbow on it).
                    BS will be a little diff., but not enough to worry about. You can see the effect yourself using (the FREE) Tolvan's "Edge" software.
                    Just plot the woof on your baffle vs about 11" wide. It won't be much different.
                    These will reach 30Hz. Pretty deep.

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                    • #11
                      Sweet. That sounds doable for him, I think. Thanks so much for your help.

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                      • #12
                        Tweeter centered or off set? Merely lined with convoluted mattress topper okay, or you think some stuffing too? Unfortunately I can't help him voice them with him being in Alaska.

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                        • #13
                          I just line w/Wal*mart mattress topper.
                          In general, centering the tweeter makes a little diffraction "blip" that goes away off-axis.
                          If he'll aim both of them straight out from (perpendicular to) the wall, then he'll be off-axis, so centered is fine.
                          If you KNOW he'll listen to them on-axis (so... angled in toward his sweet spot), off-setting (technically) could be better. 1/2" is all you need. You can see that effect using Tolvan's Edge as well.

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                          • #14
                            I'm thinking that with the increasing directivity of an 8"-er, on-axis listening might be recommended

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