I started to put together an article a year or so back using open source FEA only to find that viscoelastic damping models weren't implemented. It would have been possible to put something together without but when studying resonances getting the damping reasonably correct is required to get the amplitudes of the resonances reasonably correct. Instead I added implementing one to the to-do list but haven't got round to it yet.
3M VHB double sided tape is viscoeleastic material. Easily sourced and cheap.
The bolt with rubber washer is a good idea and makes sense to me. I don't think I'll need the rubber as the bolt will be secured to the brace but the brace will be elastic itself. I'm going to see if I can find an adhesive that will bond TPU and wood as I think that is the simplest, most elegant, solution.
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I can confirm that.
The journey starts with the material properties. I spent a couple of days to try to model the MDF material properties. (Anisotropic) At the end the measured resonance frequency of each cabinet wall was surprisingly close to the simulated result.
For a typical mid the ratio cone weight/total weight is in the order of 2%. Since panel resonances appear at mid frequencies, you could skip the woofer and tweeter. I don’t really see the issue, apart from the assumption that in normal conditions modest panel resonances would be problematic, is debatable itself.
I've used constrained layer to great effect. Loudspeaker panels shouldn't be monolithic layers of birch plywood, although that's a really good enclosure. I've found that two or three thin layers of very different materials glued strongly to each other make a less resonant panel than one solid 3/4" plywood or MDF panel. I've used 1/4" layers of HDF/Ply/veneer, one of my favorites is MDF/cement board/ birch plywood. The options are huge, you can use foam core, aluminum, lead, gypsum board, linoleum, etc. The different materials seem to diffract or refract the sound traveling through the panel. The three layers stacked seem to add stiffness. You can make panels that are lighter than plywood and panels that are heavier. It's great for experimenting and unfortunately, using lots and lots of glue. This is not the same damping technique used in an earlier post where neoprene, a soft material, is sandwiched between two layers of stiffer materials.
As far as bracing and damping go I've commented before that Dave's beautiful Jules Vern type speaker bracing actually acts as damping by eliminating any resonances in the box. Also, it's one ******* stiffly braced box.
As far as bracing and damping go I've commented before that Dave's beautiful Jules Vern type speaker bracing actually acts as damping by eliminating any resonances in the box. Also, it's one ******* stiffly braced box.
I've experimented with isolating the woofer frame from the front panel and found that supporting the woofer from the magnet with a stiff brace works best. The baffle stays isolated and a damping material gasket is between the woofer frame and the front panel. The woofer is supported by the brace that is mounted to the inside of the cabinet or to the floor. Another option is to mount two woofers back to back in a force canceling alignment. There isn't much if any improvement by placing a gasket between the woofer and front panel and then screwing or bolting them together. Also, the best results are of course with enclosures with large front baffles.