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In Reply to: RE: Room treatments? posted by author@escapeclause.net on August 18, 2007 at 15:41:01
when we know nothng about your room and the problems you are facing. How about a sketch of the room for starters with dimensions?
Stu
Follow Ups:
I am really grateful to everyone who has come forth with earnest, non-pedantic advice about this problem and I am very much looking forward to fooling around with all of this D-I-Y stuff.
I'm even more encouraged by the idea of receiving advice that is targeted to the specific characteristics and build quality of my room. The trouble is, I couldn't quite figure out how to sketch the room (because I'm an idiot). In the end I used Microsoft Excel and then took a screen capture. It's roughly to scale -- the green squares are wing-back chairs, the burgundy rectangle is a coffee table, the yellow rectangle is a couch, and the rectangles with black stripes on one side are the speakers and the TV, which sits on a TV-stand, not in an entertainment center.
The total room dimensions are 14'8" by 10'8" with a huge pass-through to the dining area on one side, and bearing walls on "two and a half" sides, broken only by the pass-through and an enormous casement window.
The quick way to find out is to listen carefully, then place a wool blanket over it and listen again.
The kind and degree of room treatments you need depend on the dispersion characteristics of your speakers. Having the large, flat, hard surface of the TV in the same plane as the speakers is likely to create confusing secondary sources with most speakers. I have to live with one myself, so I cover it with a blanket for serious listening.
The corner of the brick wall to the left of the left speaker may be another virtual source that creates sound-stage problems. Experiment with a folded blanket padding that corner.
Before you go much further, evaluate your room for slap-echo. With things as quiet as possible, clap your hands at your listening position and while standing near the speakers. If you hear a distinct metallic twang following the clap, then your room has too much long-term reverberation. This is lethal for good sound, and no amount of treatment of specific areas will overcome it. You will need large expanses of absorbing surfaces, such as carpets, upholstered furniture, and wall hangings, to treat it.
Let us know your results. I have more ideas for you.
Hi.
As HI is getting so in-home popoular, many overlook the sonic effect of a TV which when placed commonly in between the front stereo speakers.
Ideally, a stereo sound room should NOT be a HT movie muti-channel venue as well.
Too many hardwares inside the room, worst of all the big screen TV in the centre, would block out or deflect the stereo imaging & soundstaging when playing serious stereo musics let alone the adverse sonic effect due to the centre, side, & rear speakers placed over around.
Too much hardwares to allow the music to flow freely. I am still figuring out should I or not to put my HT system in as I am not a movie fan at all. My 100W 10" subwoofer is still sleeping unpacked in its carton.
As my 27" TV is placed in the centre besides my audio rack very close to the front wall, I've purposedly to move my stereo speakers up 5 ft away from the TV & the audio rack at the back wall, & 3 feet from the side wall for the right channel speaker. So there is abolutely nothing in the centre area between the stereo front speakers.
Of couse, my audio rack & the TV beside it are entirely covered up with woollen branket to minimize sound deflection when music is on.
So far it works out fine. The imaging & soundstaging come out flying colours.
c-J
Well that metallic twang you spoke of has always been present -- and I'd always hoped that targeted room treatments in specific corners (etc.) could fix it. I remember doing that test the first day I had everything moved into the new house; the old house was stick-framed and built on piers, and even way back then (2001) I just had a sinking feeling that getting good sound out of the new room was going to be a far more challenging task than a c-sharp's worth of fiberglass and chicken wire. Uggh.
It is easy to focus on specific treatments and forget that the overall appearance of the room has a profound effect on you and everyone else who uses it. An unfriendly or disjointed appearance creates a subtle stress, even if you are not aware of it. Adding localized treatments for sound until the slap-echo goes away may result in such a jumble.
I've been there and done that. If I were in your position, I would create a plan for the finished room and get it approved by your SO. Use attractive carpets, drapes, and furniture to relieve the echo first, then add compatible treatments at specific areas to bring the audio presentation into focus and with a pleasing tonal balance.
Unclestu52 is right about the coffee table and the wall-ceiling corners. Also be careful with cabinets with glass doors. The glass windows have their own problems. Covering them with curtains helps but does not cure the panel resonances. Window gel decorations or dedicated damping dots may be needed to tame the glass.
My comment about the corner referred to the exposed brick wall vertical edge that is to the left and forward of your left speaker. This edge will act as a virtual source, and confuse the sound-stage.
Different fabrics have different acoustic reflection properties. A medium-weight wool felt has about the most natural acoustic balance of reflected sound.
One thing going for me: My SO is a cat. Seriously, though: good advice. I think I'm inclined to go a little bit more "nuts" than the tone of your post might suggest (because my SO is a cat?), but your post will serve as a good periodic reality check.
You're adding to the scope of changes you want! No problem in that of course....8^)
Al's correct in that the TV set between the speakers is not really good. The way I like to set up things if the TV set is inevitable, is to imagine a plane running across the front of each speaker's face. The point of intersection should be forward of the TV set.Dampening the TV set will still help though.Since your room is relatively small, it would be helpful to really remove the coffee table, before pulling out the speakers. As Al also points out the upper corners of the room are usually a source of many issues. The meeting of the two walls and the ceiling forms a sort of 'megaphone' where sound enters and gets reflected out with increased intensity. The solution is simple: emulating the Corner Tunes from Mike Greene, simply use some painters' masking tape and tape a triangle of cardboard, about 8 inches or so on each side up into the corners. This will reduce the high frequency ringing. If you like the effect, you can use a piece of drywall, mud it in, and achieve the same effect but be visually more aesthetic.
There's a lot of things you can do without spending a ton of money.
Stu
TV is recessed about 6" into the plane of the speakers, and will go deeper once the Arcam arrives and I can get the power supply up off the floor behind the TV-stand.
Another poster talked ominously about "slap test" and "long reverberation" and I've definitely got the problem he described; I'm happy to take a piecemeal approach to all of this as long as the expense of the various staged-projects doesn't end up going to waste along the way. Do we still think, for example, that fiberglass and chicken wire tubes will do anything for a room that flunks the slap test as spectacularly as mine does?
Using the 'slap test'(actually I simply talk loudly aiming my voice to what I suspect are problem areas) you'll probably notice the upper room corners are the principle areas creating echoes. Use the 'Corner Tines' approach first. It is very cheap and easily reversible when you use that blue painter's masking tape.
While tuibe traps and things of that nature will work. concentrate on the actual room and it's furnishings itself, as all other pieces essentially become band aids.
Stu
My room exhibited some pretty bad slap echo prior to building and installing floor to ceiling Jon Risch tube traps in all four corners. There was still some slap echo remaining, but it wasn't quite as pronounced and it seemed to have changed location within the room. However, even with the remaining slap echo, the tube traps made a huge improvement in the sound of my room.
Of course the bass got tighter and deeper, but the removal of the excess bass really cleared up everything above it. Detail, imaging, soundstage, dynamics and lack of strain and congestion all improved greatly.
I have now installed several DIY wall panels at the side and front wall first reflection points. Again there was significant improvement, but the slap echo still remains. It seems to be concentrated rather high up on the rear wall. Even so, the room sounds so much better now than when I started that I am tempted to stop, except for the thought that eliminating the slap echo completely will probably make it even better. So, it looks like I still have some work to do. Perhaps I will try some sort of diffusion and/or more absorbtion on the upper rear wall. I welcome any suggestions.
Could be the rear upper corners causing the slap echo, if so, this is easy to fix.
You need something to absorb and damp the corners, like a room tune/corner tune type device.
See - DIY Corner Tune/Room Tune:
http://www.AudioAsylum.com/audio/tweaks/messages/7888.html
You can try something temporary to see if this is the problem, use some cushions, pillows, a rolled up piece of foam or polyester, whatever, stuck in the corners using duct tape, a broom, just something to keep them there for long enough to audition the room and see what happens.
If you can verify that placing an absorber in those locations does the job, then you can build the nicer loooking, more permanent versions.
Jon Risch
Jon,
Thanks for the suggestion and the link. The tube traps in the rear corners extend to within two and a half inches of the ceiling (pictured). I can pull one of the 3' tubes out of the stack to allow room to experiment with the corner trap. Alternatively, do you think there would be any benefit in trying a piece of foam stuffed into that small gap between the top of the tube trap column and the ceiling?
Brian
I would try to place some sort of absorbing material around the top of the bass trap column, whether foam, a wad of polyester, etc., so that the wooden end caps are not the only thing up in the very top of the corner.
However, this would 'gilding the lily', having the traps go all the way to nearly the top avoids the worst of such corner effects.
Jon Risch
Mr. Risch: I've been devouring your web content about the various DIY projects out there, but one thing I was wondering -- you mentioned how difficult it was to find a sound-absorbent covering fabric for DIY tube traps, and I instantly thought of grille cloth. I mean, at least we *know* that sound will pass through it, right? Any thoughts?
Speaker grille cloth, the real stuff, not some skanky unknown random double-knit polyester cloth, is very thin and easily seen through. When stretched tight over polyester batting, you can see the white polyester fibers. Unless of course, the grille cloth is a white or beige variety; since grille cloth is typically available in black, and sometimes brown, this is a very real problem.
The not-the-real-grille-cloth cloth can reflect HF's at angles greater than 30-45 degrees off of head-on into the cloth, and this describes about half of the sound reaching a wall panel. For bass traps, this is not as much of an issue, and if you are not as concerned with full range absorption, a much wider range of cloth can be used on bass traps. I still strongly recommend duplicating the ASC devices, and placing a thin plastic sheet on the one half of the bass trap cylinder, so that one can adjust the reflective half with respect to the room and the wall/corner. The amount of adjustment this allows has to be heard to be believed.
I would certainly use either grille cloth or burlap (also called jute) instead of the Guilford cloth, the cost differential is not small.
Jon Risch
The large pass through opening to the left is actually good.
The most important issue is that large coffee table. Try removing it from the room, and if things sound much better, replace it with a couple of end tables instead. Do you have curtains on the casement window or blinds, perhaps?
Stu
There's one enormous blind but, on the upside, it is made out of fabric. So the coffee table is part of the problem, huh? How very interesting -- I figured it was all of that masonry....
vertical blinds?
Most coffee tables are about knee height and have large reflective top surfaces (unless you're very sloppy like I am). I don't know what kind of speakers you are using, but if they are floor standers the woofers are probably firing (at least on the right side) directly under the coffee table. The mid/tweeters are apt to be reflecting off of the table top directly into your ears.
Stu
My coffee table is a little lower (and my woofers a little higher) than average, so the music is all above the plane of the tabletop, but that could conceivably be worse, since it means that the already bottom-heavy sound is being chucked against the table?
Anyway, I'll try listening without the table. My stepfather says he'll think about making me the bass traps.
To be continued....
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