Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

---

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tweakers' Asylum ]

---

[ Alert Moderator ]

---

Re: Help with DIY Symposium platforms

Posted by David Aiken (A) on March 5, 2003 at 13:36:05

In Reply to: Re: Help with DIY Symposium platforms posted by DSK on March 5, 2003 at 00:20:26:

Darren,

I'm sure there are ways to figure out what combinations are best in advance, but I have yet to see one documented. In my 18 months or so of experimenting with things after I started out with a plywood/bubblewrap platform (I found that idea in a Michael Fremer column in Stereophile), I tried a variety of things in the middle between the plywood including polystyrene, neoprene, balsa and even a couple of combinations of materials. In each case I thought the combinations sounded worse than the single layer in the centre. I didn't try aluminium or steel on the outside - I got sidetracked onto a different approach and never went back.

My guess is that the "soft" layer is more critical than the outside "skin" of hard layer, and it's easier to stuff the results up there than anywhere else. Single layers seem to work fine with a suitable material and you can notice differences between materials. Multiple layers interact with each other and that can result in interference or enhancement, and all I got seemed to be interference - at least from my view. Part of the reason may have been that one or more of the soft layers acted as a spring and that the resonant frequency of the whole construction was too high. That would result in the platform not only passing low frequency vibration through, rather than absorbing it as intended, but also actually magnifying the low frequency vibration under some circumstances.

Sunnysal in his response to you suggests the use of multimaterial pads such as black hole. I'm not a speaker builder and I haven't tried black hole but I thought that it was intended to absorb sound waves inside the speaker cabinet and that isn't quite the same as absorbing conducted vibrations. I would expect something intended to absorb sound waves to possibly be a little too soft and to squash tto some degree under the weight of whatever component sits on top of the platform. My feeling is that squashing under pressure in use is not good. I did recently play around on a very small platform for a power filter with a MDF/dynamat/MDF sandwich and that seemed reasonable so I think Dynamat would be a good candidate to try for a centre layer, especially as it doesn't seem to deform under the sorts of pressure I've seen, even using it in small circles between my speakers and their stands.

I think adding aluminium or stainless steel plates to the outside is fine and I'd keep them fairly thin - around the 2-3 mm thickness or 1/10th of an inch or so. I don't like the idea of adding too much mass so I'd go for aluminium over steel myself, and the ring of aluminium when struck is nowhere near as defined as that of steel which I think is a plus (that's two of the reasons I made my rack out of aluminium). The timber it's glued to will damp the resonance anyway. In the centre I'd stick to polystyrene, one of the vibration damping foam rubbers, or possibly dynamat.

David Aiken

This post is made possible by the generous support of people like you and our sponsors:

Parts Connexion

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---