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I live in a large cement room...

Hi. I would be grateful for anyone out there with acoustical knowledge to offer ideas. Here's my system, room, and issues to address;
#1. OK, THE SYSTEM: Cary CD303, Cary sli80 (with a buffet of NOS tubes, so sexy they're almost pornographic), Meadowlark Hot Rod Shearwaters, 2 Coincident power cords, Harmonic Tech Pro silwayII interconnects, a Chang Lightspeed on the way, and biwired DH Labs T-14 (soon to be replaced with either Harm Tech Pro9 bi's or the Coincident wire). That will be all the upgrades for quite a while, I took some big steps this past year to put together a good system for what I listen to, which is primarily small ensemble acoustic instruments- jazz & classical.
#2. THE ROOM: length 24' width 17' height 8'. Hard tile floor, cement walls, and cement ceilings sprayed with stucco textured with kitty litter, wasn't my idea but it's a nice effect.
Currently I have my speakers 8' out from the short wall ( I live alone :-), and 4' out from one of the long side walls, and 7' from the other side wall, (it has to be this way due to foot traffic considerations), the speakers are about 7' apart from center of drivers.
ROOM TREATMENTS I'VE DONE ALREADY: the whole back wall is covered in two king size egg crate bed pads, then covered by two king size Martha Stewart (taupe colored) cotton blankets, a nice looking wall if I do say so with lots of double stick carpet tape underneath and duct tape on the perimeters. On the floor I've put two throw rugs- Kmart designer rugs, (~4'x7') from the exclusive Tangiers collection, which I throw out and replace whenever the dogs vomit on them. So there is a thin layer of carpet all around me between the speakers and my listening position. On the long wall to my right of the listening position (with the speaker 4' from the side wall) are two large sliding glass doors with panoramic views of the Caribbean, ( I'm in St Thomas, which is why the house is all poured cement). There is a sheet thin drape over the windows. Behind the speakers along the back wall are lots of cardboard boxes from all my equipmemt, and CD racks etc.
ISSUES TO ADDRESS: How can I improve my soundstage/imaging? Speakers are slightly toed in. I don't seem to be able to attatch anything to the ceiling due to the kitty litter, it just wont stick. I think better speaker cables will help. Frequency response seems nice, but I'd love to hear even better imaging. Sorry to be so long winded but I just finished a nice bottle of wine. Jay
jay_carlson

Showing 2 responses by sean

sean
6,231 posts
 
Ezmeralda is right on. Most foam is not NEARLY as absorbent or linear as most folks think that it is. As such, it can totally skew the frequency response of the room. I would HIGHLY suggest checking out Jon Risch's website. Sounds like his sound absorbing panels, bass traps, etc... would be right up your alley. They are also extremely cost effective. As a matter of fact, i think that he even has DIY versions of the room lenses mentioned above. You can probably build several sets for WELL under $100. Sean
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sean
6,231 posts
 
I stand by my statements pertaining to the non-linearities of foam. This even applies to "professional grade acoustic foam". If you don't believe me, read what one of the foremost experts in the acoustic industry has to say: RPG.

http://www.audioadvisor.com/store/productaddimage.asp?sku=RPGPF2212&InfoType=-1&ImageIndex=2

If you follow the red line on the chart, this is equivalent to the 4" of foam that Evo mentioned. For a quick comparison, take a look at the other frequency response graphs. As you can see by RPG's own charts, the results of using professional grade foam can REALLY skew the tonal balance / frequency response of a room if your not careful with it. This is due to the fact that it does not absorb all frequencies in a linear fashion. Now if you take into account that "non-acoustic foam" will have different and uncharted ratios of absorption across the band, you can REALLY get into some hard to deal with and irregular responses. I'm NOT saying that foam won't work, just that you have to know what your working with and how to get the best results from it.

For a good reference on working with acoustics, you might want to pick up a book by F. Alton Everest entitled "the master handbook of acoustics, volume 4". Here are two different sources. Depending on what you might need or where you might order from first will depend on where it is actually cheaper / more convenient to get it from. Otherwise, it is the same basic price.

http://www.partsexpress.com/pe/showdetl.cfm?&User_ID=2072806&St=4895&St2=50927711&St3=83636294&DS_ID=3&Product_ID=11049&DID=7

or

http://www.amazon.com/exec/obidos/ASIN/0071360972/o/qid=991464662/sr=2-1/002-2986522-8592812

Hope this helps and clears things up a bit. Sean
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