Soundtreating a small room

[Erukian]

I've got a couple hundred to spend on sound-treating material for a room that's 10.5x12.

I've completely equalized out the bass so it sounds great, flat from 20hz to 200hz. But I feel my mids and highs are suffering. I'm wondering if anyone here has any experience in what is some cheap and effective material for doing the job, where I would apply it, etc.

Thanks,

-Joe

[sfogg]

Joe,

Do you have WAF issues or are you free to do to the room what you please?

If you have free reign in the room:

www.foambymail.com

Has a few different varieties of acoustic foam for sale and better prices then most places. They sometimes sell on ebay even cheaper. Avoid the 1" stuff but the rest of it works well. Don't use their glue though... use Liquid Nails.

I have a 9x17x7 theater room and used their 2,3 and 4" foam in it extensively. My room went from being *extremely* live (all walls double drywall) to be quite dead which is what I wanted. My entire ceiling is 2" foam, front wall is 4" foam, side walls up front is 3" tappering down to 2". Then bare wall on the sides and rear in the back of the room with one horizontal strip of the foam across the back wall leading onto the side walls to kill a slap echo in the rear of the room.

Shawn

[rplace]

If charcoal and burgundy colors will work for you I have some extra absorption panels I would let go cheap. I also have some diffusion panels that are currently white but can be painted to any color.

Take a look at http://www.truesoundcontrol.com/products/absorption.html

I have a mix of the following:

2" Studiofoam Wedges

DST-422 Studiofoam

DST-114 Studiofoam

Q'Fusor Sound Diffusors

I can get you a more detailed inventory if you need it.

Good Luck, Rich

[Speedball]

Inexpensive rugs and runners from a local home improvement store, it looks pretty good too!

[PrestonTom]

You are actually asking a pretty tough question.

If you are satisfied with the bass, then you are way ahead of the game. I would sugesst spending some time experimenting with the locating the speakers and chair (use a carefully recorded CD and listen, listen, listen at various locations and arrangements). The determine what deficits you think you have, this is sometimes difficult to put into words or categories. The frequency response should be even and the imaging should be good. Detemine the deficits and then treat the room. As others have mentioned, the treatments can range from decorative ones (drapes, curtains, wall hangings) to ones you find in a studio (sonex etc).

Good luck,

-Tom

[pauln]

Keep in mind that you only have to treat three orthagonal surfaces - two non-parellel walls and either the ceiling or the floor. If you have a carpet your one third done.

Paul

[DrWho]

I've got a couple hundred to spend on sound-treating material for a room that's 10.5x12.

I've completely equalized out the bass so it sounds great, flat from 20hz to 200hz. But I feel my mids and highs are suffering. I'm wondering if anyone here has any experience in what is some cheap and effective material for doing the job, where I would apply it, etc.

Thanks,

-Joe

just curious, what kind of EQ are you implementing? Though you may identify the problem as related to the midrange, the bass response actually has a lot to do with the overall smoothness of the mids and highs. Also, what speakers are you running and what was your process of EQ'ing the system and where in the signal path is it? The reason I ask is because it really is impossible to flatten out the bass response using EQ...especially in a room your size. How are you measuring this?

As far as room treatments go, I would start off by getting the speaker positioning as good as possible: point the speakers at your head and try to avoid as many reflections as possible. Then I would suggest treating the early reflection points and going from there.

[Erukian]

oohh, lots of questions!

First, I have a pair of Klipsch Reference Bookshelf 25's in a room

that's 10x5.11, their on one of the 10.5's walls. Their positioned

approx. 6" away from the wall (front port remember) and 3 feet away

from the side walls, so their about 5 feet apart, and my head is about

4-5 feet away in a sort of small triangle. Pretty nearfield listening.

Oh, my sub is a HSU stf-2, which holds to it's specs and is rated down

to 25hz +-2dB.

I'm using a 32band digital parametric equalizer. So I can set the hz to

the decimal point, so say I have a calculated room mode at 215Hz, and

my SPL meter shows a gain of about 5dB. What I would do is set the

center frequency on the para-eq to 215.0, set the gain to -5dB and set

the bandwith to however much of the range is being affected by the room

mode.

I used a cheap rat-shack SPL meter and I did use those compensation

charts that tell you what to add on and take off of the meter's reading

when your calculating bass. The xover on the sub is set to 60hz so

there's a slight overlap, but when I run long sweep tones using my

computer. Say 200Hz to 100Hz and over 60 or 90 seconds then 100hz to

20hz again, over about a minute, after I set up about 12 or so para

EQ's, the sound was audibly flat, as well as +-3dB on my SPL meter

(again, after I compensated the values).

-Joe

[PrestonTom]

Okay, I am starting to undersatnd the issue now. ....

First, using an equalizer is not really a very good way to tame room acoustics.

Second, Dr Who gave some very good advice.

Good Luck,

-Tom

[DrWho]

oohh, lots of questions!

First, I have a pair of Klipsch Reference Bookshelf 25's in a room that's 10x5.11, their on one of the 10.5's walls. Their positioned approx. 6" away from the wall (front port remember) and 3 feet away from the side walls, so their about 5 feet apart, and my head is about 4-5 feet away in a sort of small triangle. Pretty nearfield listening. Oh, my sub is a HSU stf-2, which holds to it's specs and is rated down to 25hz +-2dB.

I'm using a 32band digital parametric equalizer. So I can set the hz to the decimal point, so say I have a calculated room mode at 215Hz, and my SPL meter shows a gain of about 5dB. What I would do is set the center frequency on the para-eq to 215.0, set the gain to -5dB and set the bandwith to however much of the range is being affected by the room mode.

I used a cheap rat-shack SPL meter and I did use those compensation charts that tell you what to add on and take off of the meter's reading when your calculating bass. The xover on the sub is set to 60hz so there's a slight overlap, but when I run long sweep tones using my computer. Say 200Hz to 100Hz and over 60 or 90 seconds then 100hz to 20hz again, over about a minute, after I set up about 12 or so para EQ's, the sound was audibly flat, as well as +-3dB on my SPL meter (again, after I compensated the values).

-Joe

How do you have the equalizer wired in your system? Are the RB-25's connected to it?

One note of caution, playing solid test tones in a room creates standing waves. If you move your meter around when playing these tones, you'll notice that it could vary by as much as 20-40dB! (which makes it difficult to make 3-6dB changes accurately). I can see where the logic is coming from, but it just doesn't work. Most of the frequency nonlinearities are due to the acoustics of the room (especially moreso at lower frequencies). Trying to counter-EQ the room causes a lot of wierd things to happen; to make a simple analogy: The direct sound always arrives at your ear first, and then any reflections (that would be affecting your measurement) arrive later. Let's say your speakers are about 3 feet from the side wall, which will cause a 6dB dip at 100Hz (let's use a 100dB reference tone, which places -6dB at 94dB). After matching the curve and boosting the signal by 6dB, you now increase the direct sound by 6dB (100dB), but you've also increased the magnitude of the reflection, which will bring the overall sound back down to 94dB! Many however still percieve that the EQ has helped because they have in fact quadrupled the cone excursion for the same SPL, which of course increases the distortion...and as long as the distortion doesn't sound "bad", it will sound as if the 100Hz signal is louder, when in fact it is not (just that our ears fill in the gap from the harmonics we hear). But keep in mind that the direct sound does arrive earlier...if the original direct sound is flat at 100Hz, you have now boosted it by 6dB for a short period of time. So I suppose there is a bit more 100Hz material but it is on the order of a few milliseconds (then once the reflections start arriving you're back to no sound). Anyways, the situation is a bit more complicated than this, but I hope I've painted the picture well enough. You would get better results using an RTA (which with an available computer can be had for $100). Even better results could be obtained with a TEF but they are expensive and have a steeper learning curve.

When EQ'ing, you have to realize that it is a huge mental battle. Just about any changes you make will at first sound better...mostly because you are actually hearing a change. Come back to your system a few days later and A/B between EQ on and off and I think you might be surprised how much more natural the off setting sounds. If EQ on sounds better, then consider it a good EQ...but make sure you try it on all sorts of source material. Different songs bring out different flaws. I really have a strong inclination though that your EQ might be responsible for part of your HF,MF problems...getting that bass right makes a world of difference with the clarity of a system. Also, if your RB-25's are impacted by the EQ, then you are probably overdriving those little woofers which will also hurt the midrange. Btw, what kind of reciever/amp are you using? Are your mains set to small and how are you crossing over to the subwoofer?

I just wanted to mention another thing...the LENRD Bass Traps from auralex (I forget the other cheaper online retailer that makes the same product) also act as diffusors in the corner (due to the shape of the panel face). They will also absorb at bit at high frequencies as well which should help with the pinginess of the room. When you clap your hands, do you hear a quick and almost equally as loud "slapback" echo? This is due to having too many parallel surfaces. Adding furniture, bookcases, and all that other kind of stuff will help to reduce this (not to forget acoustic panels of course).

There is also the curved masonite approach which is extremely cheap and the panels act as diffusors and a bass trap (moreso if you fill in the space behind them with an absorbtive material). You could also build your own bass traps using Roxul 60...if you wanna go that route let me know and I can help you find a store that carries it (you don't want to go to a Home Depot or similar store because it's very expensive there....go to one of those contractor places).

[mikebse2a3]

oohh, lots of questions!

First, I have a pair of Klipsch Reference Bookshelf 25's in a room that's 10x5.11, their on one of the 10.5's walls. Their positioned approx. 6" away from the wall (front port remember) and 3 feet away from the side walls, so their about 5 feet apart, and my head is about 4-5 feet away in a sort of small triangle. Pretty nearfield listening. Oh, my sub is a HSU stf-2, which holds to it's specs and is rated down to 25hz +-2dB.

I'm using a 32band digital parametric equalizer. So I can set the hz to the decimal point, so say I have a calculated room mode at 215Hz, and my SPL meter shows a gain of about 5dB. What I would do is set the center frequency on the para-eq to 215.0, set the gain to -5dB and set the bandwith to however much of the range is being affected by the room mode.

I used a cheap rat-shack SPL meter and I did use those compensation charts that tell you what to add on and take off of the meter's reading when your calculating bass. The xover on the sub is set to 60hz so there's a slight overlap, but when I run long sweep tones using my computer. Say 200Hz to 100Hz and over 60 or 90 seconds then 100hz to 20hz again, over about a minute, after I set up about 12 or so para EQ's, the sound was audibly flat, as well as +-3dB on my SPL meter (again, after I compensated the values).

-Joe

Joe from what I'm reading in your post it sounds like you have done a good job EQing your low frequencies(I'm assuming you use one listening position in this size room) if you are mostly taking out peaks and like others have advised watch out trying to fill in dips especially if they don't show improvements with small amounts of boost. Its not clear to me but are you also EQing above the low frequencies you have mentioned? Anyway I have dealt with rooms close to the dimensions you have and they are difficult to get a good tonal balance and clarity in because as the room dimensions get smaller the very intense early(time wise) reflections appear higher in frequencies than larger rooms and this is one of the main reasons smaller rooms are more difficult to deal with and use acoustical treatments in. It is very easy to over do the absorption option in this size room especially if carpet is used on the floor. To much absorption just eventually wears on you and ultimately sounds unnatural even though you might notice some improvements in say imaging you don't want that at the cost of a natural tonal balance and life like impact and transients which again to much or the wrong placement of absorption can cause. I personally like diffusion in smaller spaces but again because of early reflections due to small room dimensions you must listen and decide if what and where your placing the diffusers are causing coloration just as absorption can color the sound. I personally have used diffusers about three feet behind my listening position on the back wall with a thick pillow behind my head to block the early reflections from the diffusors thus giving myself a clean early sound but a much more diffuse soundfield in the room which goes a long way to adding clarity and good tonal balance without sucking the life out of the music as absorption can do. Anyway have fun experimenting and learning about room acoustics and smaller rooms like this can be a real challenge getting corrected but you can get some very wonderfull sound if you are willing to work at it and show alot of patience!!

mike[]

By the way the EQ is a valid tool just as absortion and diffusion and when used correctly I believe can improve your enjoyment of your music in your unique enviroment.

[DrWho]

Ya, I didn't mean to come across as bashing the EQ...just trying to poke at possible reasons for his dissatisfaction with the HF and MF. Btw, I am a firm believer in using EQ as well...just trying to fill you in on some more pieces of the puzzle to think about []

I also agree that diffusion is the way to go in a small room...though some absorbtion will be needed to "soak up" the reflecting signals...though this gets into the realm of a lot of trial and error or fancy modelling equipment. I suppose there is also the route of hiring someone else to do the thinking for you, but what's the fun in that? []