[mulveling]

In another speaker forum (polkaudio), a member commented that placing slate slabs under each tower speaker vastly improved their sound. That got me to thinking about my own 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 (that is to say, great) in either room. 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 these large surfaces have so much "give".

Too curious to wait, today I picked up a pair of Auralex Gramma isolation platforms ($50 each @ Guitar Center) and placed one each under my mains. They're thin wood wrapped in some kind of coarse fabric, with thick Auralex foam for the base rails (and with squishy wedged purple foam between the rails). Unfortunately, combined with my padded carpet, this causes wobble issues with my 4' tall tower speakers (it's easy to rock the speakers when pushed from the top). Fortunately there's no kids/pets around and I don't think this will affect the sound too much - the important thing is to decouple the speakers from the suspended wood floor, which it does. I think about it this way: headphones can still sound great while you're moving your head - that's analogous to the speaker wobbling. What's important is to control the vibrations within the headphone's frame/earcup - that's analogous to decoupling the speakers from the floor (as an added benefit this should provide some additional sound isolation from neighbors below).

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 & agile rather than just boomy. Mids are crisper with much more realistic vocal projection. Imaging isn't too localized to the boxes, like before. Soundstage is expanded. Highs are clean, smooth, and with more sparkle. Tone - oh my, how much more natural and realistic the tones of instruments sound. Have my dreams come true?

This was like a significant speaker and/or room treatment upgrade, and it only cost $100. Again, I think it helped more than usual in my case because of the crappy wood floor.

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 bass traps placed on the front wall, and they DO make a measurable difference in low-frequency decay (according to the Room Eq Wizard (REW) LF waterfall graphs), but the qualitative sonic improvement from those is nothing compared to that of the Grammas!

 

[Hoppergrass]

makes sense to me. i may try it myself as i've just
bought my first "real" set of floor speakers.

 

[mulveling]

Quote:

Originally Posted by Hoppergrass /img/forum/go_quote.gif makes sense to me. i may try it myself as i've just bought my first "real" set of floor speakers.

Cool, Polk LSi15 - I used to own those, when I was in my old room. Check out the polkaudio forums.

Give this tweak a shot; though the LSi15 already has its own sort of stand, which may do part of the work. For my system it was huge - it makes obsessing over cable, source, and amp changes seem silly. Usually with speakers there's going to be *some* kind of acoustics/room tweak that'll have a bigger effect than electronics - yet it's ignored by most audiophiles. Some guys have really serious gear with no room treatments at all. Look at the lack of interest in this topic

I know I got caught up in the equipment-go-round before I decided to look into room issues.

I've also started using software that allows me to plot FR graphs of my room and will also analyize bass decay issues (so I can see the effect of bass traps & placement).

 

[warpdriver]

I use one under my sub. It works great. You lose a bit of that "my floor is shaking out of control" feeling, but in return you get bass that feels tighter, and far more musical (with ANY change in measurable frequency response, I checked)

 

[bhd812]

clay bricks with a slab of wood on top is the same principal as those...

just a bit cheaper and can be made to look much cleaner easy

 

[dura]

Interesting tip, i'll remember this.

Coupling LS to the floor is for me the #1 tweak.
Every chance of material is clearly audible.

 

[mulveling]

Quote:

Originally Posted by warpdriver /img/forum/go_quote.gif I use one under my sub. It works great. You lose a bit of that "my floor is shaking out of control" feeling, but in return you get bass that feels tighter, and far more musical (with ANY change in measurable frequency response, I checked)

Cool, good to hear it's working for someone else. I've got big tower speakers w/ three 10" woofers run full range, so those are like my subs.

I couldn't care less about tactile bass feeling, even for movies. All I want is tight, textured, musical bass.

Yep, a frequency response plot can be useful but there's still a whole lot it doesn't say. A few days ago I measured my room with and without the few LENRD bass traps I've got - frequency response plot looked exactly the same, but the LF Waterfall analysis (via REW software) showed a significant improvement with the traps.

Quote:

Originally Posted by bhd812 /img/forum/go_quote.gif clay bricks with a slab of wood on top is the same principal as those... just a bit cheaper and can be made to look much cleaner easy

Yep, that sounds pretty effective. More audiophiles should know & love this tweak. Forget about expensive brass spikes for full-range/subwoofer speakers; isolation platforms are what's needed.

 

[ooheadsoo]

That depends on the floor and wall materials. It's not always better, but it could be on a per application basis. I, on the other hand, definitely want the tactile bass feeling, because it's always there when you listen to music live.

 

[warpdriver]

Quote:

Originally Posted by ooheadsoo /img/forum/go_quote.gif That depends on the floor and wall materials. It's not always better, but it could be on a per application basis. I, on the other hand, definitely want the tactile bass feeling, because it's always there when you listen to music live.

There's a difference between tactile bass, and uncontrolled resonances from a non-rigid structure. That's where putting these Grammas will help, you still get the same amount of bass going into the room, but less energy is being transferred to the floor directly.

 

[ooheadsoo]

Right, it depends on how rigid the floor is. On my carpet over concrete, I don't want the grammas, but if you're on some old ply or whatnot, sure, maybe.

I'm not sure bricks would work. You want a lossy material that will absorb the energy being transmitted by the speaker, and brick doesn't seem to be it.

 

[bonesinc]

I bought 4 square, concrete, pavement tiles, 8 rubber dampers for washing machines and 8 spikes for my floorstanders.
I have carpet on a wooden floor and I got more clarity and tighter bass using the following setup:
Put 1 tile on the floor, put 1 rubber damper on each corner of the tile, put another tile on top of that and then the floorstanders (on 4 spikes!).

Works great and it's cheap! Cheap enough to give it a try, I would say.

 

[bhd812]

when i read threads like this it truly pains me to read about people absorbing sound....

I been there and done that, I have or had Auralex,8th nerve,and ASC products..
nothing made me happy with the sound no matter what I did..

Then I figured out "why the screw do I absorb? the speakers job is to reproduce sounds..when i absorb i kill/stop the speakers job.."


I found out the nutty (and i mean deeply nutty) way from the MGA guys over at tuneland are down the right path. they don't absorb but instead control the sound..which is the point.
sad part is 99% of the speaker world does absorb, oh well if your happy with having all the sounds come just from the front wall then more power to you..
i on the other hand want my rig/room to reproduce sounds 360 around me..of course that's hard to do but I am about 30% their..amazing.

it really does send a shiver down my back when i read people absorbing..but thats me

 

[alienman]

Forgive my intrusion, but I really don't understand what you're talking about. Are you talking in general about acoustic treatments when referring to "absorbing sound," or only about speaker isolation/coupling?

Most people would feel that with a wooden floor or subfloor, it's not the floor's job to reproduce sound. Likewise, in a room with bare concrete walls, floors, and ceiling, most people would want to get rid of most of the echo. Are you saying that you desire these traits in your listening environment?

The way sound interacts with your room causes sound to eventually reach you in all directions if little or no absorption is present, so I really don't see how you've only reached 30% of your goal of having your system "reproduce sounds 360 degrees around" you. Do you mean to say that your room is is comprised of materials that are absorbing 70% of your speaker's output which you wish to remove?

You can control the sound using diffusors, but that's not always the best solution, as you'd need rather deep wells to control bass. That's why many use corner bass traps which absorb the frequencies at which there is too much bass energy, with the idea being that they wish to balance the frequency response.

Remember that everybody has a different room that they are dealing with and that what works for you may not work for someone else.

This is just my 2 cents and I do hope that I don't offend anyone. I am by no means an expert, and I have never stayed at a Holiday Inn.

 

[mulveling]

Quote:

Originally Posted by bhd812 /img/forum/go_quote.gif when i read threads like this it truly pains me to read about people absorbing sound....

Well in my room the difference was of such positive significance that before the platforms & bass traps I couldn't enjoy music from this rig - but now I can. Also, in the first post I stated my room's conditions and why I thought this was the right solution for my room.

I'm also with alienman in that I'm not really sure what you're getting at - the "sound control" I seek is to keep acoustic production localized to the drivers as much as possible, reduce room modes where possible, etc - one way of achieving that is properly placed absorption materials. Obviously too much absorption will make the room sound dead, and this is certainly not my aim - far from it.

If this kind of sound is pain, then I'm a severe masochist

 

[dknightd]

Thanks for reminding me I really do need to experiment with how my speakers sit on the floor. Right now I'm using the rubber feet. I have hardwood floor and would rather not mess it up with spikes. I think I'd rather isolate than couple. I wonder how much if any change in sound is due to vertical positioning of speaker. I think I'm to the point of trying different speaker "stands".
My first thought is just putting the speakers as is on top of pieces of leftover
rigid fiberglass. Maybe with a piece of wood in between. I'm curious to see how much if any difference it makes. I think my speakers (b&w 703) might
sound a little better if I elevate them a bit. It might be hard to seperate the difference due to vertical placement to that due to coupling with the floor, but as long as the difference is positive who cares. Maybe next weekend I'll play a little.