Guerrilla tactics for mounting Alpair 7.3 drivers in old cabs - diyAudio
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Old 1st January 2012, 12:47 PM   #1
rongon is offline rongon  United States
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Default Guerrilla tactics for mounting Alpair 7.3 drivers in old cabs

Happy New Year, everybody!

I'm all set to order my first pair of Alpair 7 drivers, am looking forward to it. But, cabinets are a problem for me. I'm the world's worst woodworker, and I'm now far from friends with the right tools, etc. I only have some very basic tools, but there is a Home Depot nearby .

I have a pair of old B&W DM100 speakers whose drivers have gone bad after 30 years. The cabs are simple, sealed, about 0.3 ft3 (8.5 liters). I lined the insides with plastilina years ago. I'm thinking of using the cabs for the Alpair 7's. A quick run of the T/S parameters in WinISD suggests this will work fine. If sealed, box Q = 0.65. If ported, Fbox = 55 Hz or thereabouts.

Of course, the problem is how to create a new baffle for these boxes. I was thinking of using one of those 1/4" thick MDF project panels, cut it down to fit flush over the current baffle board, carefully cut the holes for driver and port with my saber saw. (Those holes won't look too good, but the idea is to hide them.) Glue and clamp the new baffle to old, right on top. Add a layer of duct seal to any areas that aren't directly glued to the old baffle.

My biggest problem will be routing the mounting holes to flush mount the drivers. How about if I front mount the driver in a straight hole in the baffle, then build up the area around the driver with easily cut materials like cork and felt?

- First a layer or two of adhesive backed cork goes over the baffle, cut to fit around the driver. (Natural cork Contact paper?)

- Next a layer of adhesive backed black felt goes over the cork.

I figure the felt will reduce baffle diffraction effects and won't look too horrible.

Is this totally stupid, or will that work to "fake" a flush mount?


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Old 1st January 2012, 05:20 PM   #2
rongon is offline rongon  United States
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I had a different idea. Let's say...

- I take a 1/4" thick piece of MDF and cut that to the shape of the pre-existing baffle.

- Cut a mounting hole in it for the driver, 4-1/16" (103mm) diameter.

- Cut a second 1/4" thick piece of MDF to the shape of the pre-existing baffle, but make the driver hole larger on this piece, 5-5/16" (135mm) diameter, to fit around the front edge of the driver mounting ring.

- Clamp and glue the two baffle pieces together, aligning the two holes so that there's a 1/4" recess to fit the mounting ring of the driver. (Boy, this driver has a large mounting flange.)

- Add my layer(s) of cork and/or felt to be just flush with the driver mounting ring.

I could even make the second 1/4" layer a little smaller around the outside than the first, to put a stair-step around the edge of the baffle. I could fill that with something soft (cork?), to soften edge diffraction effects.

So, any opinions on this?

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