# Anyone Tried Speaker Isolation Platforms?



## mulveling (Feb 14, 2007)

Hi all, 

In another forum, a member commented that placing slate slabs under each tower speaker vastly improved the sound. That got me to thinking about my room problems - I'd noticed a dramatic decrease in the sound quality of tower speakers since I moved from a first floor apartment (carpet over concrete slab) to the top floor (carpet over suspended wood). Most notably, my Tannoy Eyris DC3 towers dropped significantly in clarity, while my stand-mounted Tyler Reference monitors sounded pretty much the same. Furthermore, I've heard my Legacy Sig III's in my friend's room (thin carpet over concrete), where they sounded MUCH better than my current room. At first I thought this was due to traditional reflective/modal acoustic problems, but the old room and the new one are pretty similar in dimensions & layout. The one major difference is the floor support - in the new room the floor & walls shake when I jump & land. In the old room nothing moved. 

I got to thinking today - perhaps the problem is the coupling between speaker & floor: vibrations from the speaker transfer to the floor & walls, which may then convert vibrations back to acoustic energy since they have so much "give". Does this sound reasonable?

Too curious to wait, today I picked up a pair of Auralex Gramma isolation platforms and placed one each under my mains. My qualitative first assement - no measurements yet - is that the sound is MUCH cleaner. Sounds MUCH more like the rooms with solid floors. I listened using Tracy Chapman's debut CD (which I'm familiar with) on my rig:
Denon DVD-3910 > Sugden Headmaster > PS Audio HCA2 > Legacy Audio Signature III w/ Auralex Grammas
Bass is now textured rather than just boomy. Mids are crisper with better vocal projection. Imaging isn't so localized to the boxes. Soundstage is larger. Highs are clean, smooth, and with more sparkle. Have my dreams come true? 

What do you guys think? am I crazy? 

*Edit* - FYI, each Legacy Sig III has three 10" woofers: down-firing, front-firing, and back-firing. There's lots of bass & movement to keep under control! I've also got 6 Auralex LENRD traps placed on the front wall, and they DO make a measurable difference (according to the REW LF waterfall graphs), but the qualitative sonic improvement from those is nothing compared to that of the Grammas!


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## blownrx7 (Feb 7, 2007)

Mulveling,
Don't think you're crazy at all. At least not for the speaker isolation suggestion:heehee: 
It makes perfect sense that isolating the speaker from the floor that is acting as a trampoline and soundboard would improve the clarity of the sound delivered.
Especially true with a down-firing woofer!


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## Ethan Winer (Jul 21, 2006)

mulveling said:


> perhaps the problem is the coupling between speaker & floor: vibrations from the speaker transfer to the floor & walls, which may then convert vibrations back to acoustic energy since they have so much "give". Does this sound reasonable?


There are two related issues. One is that speaker cabinets vibrate a little (though ideally they wouldn't), and those vibrations can cause the floor or whatever it's resting on to also vibrate sympathetically at certain frequencies. The other issue is that sound waves travel through solids faster than through the air. So if the floor vibrates, some of the energy gets to your ears early, which creates comb filtering peaks and nulls.

I'll also add that claims of "incredible difference" after decoupling loudspeakers are probably more imagination than reality. Unless you have big speakers on a really flimsy table top, the improvement from decoupling is modest at best. And certainly far less than the improvement from adding room treatments like bass traps.

--Ethan


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