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the walls will still be relatively thin. The inner box is 11.5mm thick panels. I've undersized the box by around 13mm, allowing an outer box to be made of the same 11.5mm panels. I can't use thicker panels for the outer box or it won't fit on top of the inner box.
The front baffle, because of how I have things arranged, can be thinking and I'm thinking of using the 17.5mm sheet for the outer front baffle for total of 29mm, total just over an inch.
Trouble with a vertical brace that is parallel to the front baffle (as I proposed in my earlier post) is that it once it is glued into place cuts off access to the front half of the box for fitting additional smaller braces. This is where the horizontal shelf brace helps because now I can easily reach into the box to add a number of smaller braces which will be larger in number so that I end up with no large areas of unbraced panel. These smaller braces could more easily be installed at some angles too.
The horizontal shelf braces also add more strong bracing to the front baffle and behind the driver where perhaps the most help is needed. So I think I'm going to go for this arrangement.
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Lossy material
In addition to a choice of glue materials to bond together the inner and outer box there is also the option of using a thin sheet of some lossy material. I believe SpeakerDave recommended neoprene. Well, there are suppliers of the stuff in sheet form on ePay. Anybody have any data to share on neoprene vs glue (e.g. silicone glue) ?
In addition to a choice of glue materials to bond together the inner and outer box there is also the option of using a thin sheet of some lossy material. I believe SpeakerDave recommended neoprene. Well, there are suppliers of the stuff in sheet form on ePay. Anybody have any data to share on neoprene vs glue (e.g. silicone glue) ?
Some years ago North Creek Music sold a soft glue in one quart bottles.
I used it successfully to double speaker panels (baltic birch and Ultralight MDF).
It was very effective.
I called North Creek about a year ago to get some resistors and asked
about the glue, and he said he no longer carries it but that you can
get it from Walmart. This is what he mentioned:
Aleene's Original Tacky Glue, 16 oz: Office : Walmart.com
I'd glue up a couple pieces of waste wood first and see how it works, just
to be safe, but the original stuff gave me beautifully dead 1.5" panels.
Skip Pack
I used it successfully to double speaker panels (baltic birch and Ultralight MDF).
It was very effective.
I called North Creek about a year ago to get some resistors and asked
about the glue, and he said he no longer carries it but that you can
get it from Walmart. This is what he mentioned:
Aleene's Original Tacky Glue, 16 oz: Office : Walmart.com
I'd glue up a couple pieces of waste wood first and see how it works, just
to be safe, but the original stuff gave me beautifully dead 1.5" panels.
Skip Pack
Neoprene is good stuff. Silicone is also good. I don't have data, but I can look
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There's no data on Tacky Glue, even the MSDS refuses to give up any secrets.
I think Silocone is the front-runner.
Magnet brace - given the strength to the cast frame, I'm wondering if magnet support doesn't put undue stress on the magnet and the real gain is to be had from bracing the rear of the frame somehow ?
I think Silocone is the front-runner.
Magnet brace - given the strength to the cast frame, I'm wondering if magnet support doesn't put undue stress on the magnet and the real gain is to be had from bracing the rear of the frame somehow ?
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something like this?
Tannoy 15" dual concentric circa 2002
build the endo-skeleton first, dado exterior panels
next (?) time, BB ply for the whole thing 1" MDF is a mf to work with on a box this size - well over 100hrs start to finish, and at least 200lbs each with drivers installed.
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Well, this is an inspiring build Chris. Just happens I have a half panel of birch ply left over from another project so I can make up a 3rd shelf brace as in your design. I've cut the braces to size, just the external dimensions, a lot more is needed to turn them into holey braces. I think it's going to be an interesting challenge.
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I decided not to do that because I'm not so sure that's how I want to brace the magnet so I've created a clearance space - but it will be relatively easy to add a magnet brace (e.g. by gluing it to the holey brace) - and I have time to worry about the design for that whilst I finish the basic construction. I may opt for something that 'grabs' the magnet rather than just presses against the back of it.