Need room treatment help

madmax

I have a room that is 14x22 with a closed stair case going up one side. This leaves a room which really looks like it is 11x22. No matter where I put the speakers I always end up with a midrange hump somewhere around 1Khz to 3Khz. For example, most average voices are accentuated to the point of glaring through your head before the bass and treble even have a chance. I'm guessing this has to do mostly with the two parallel walls being 11' apart since it doesn't matter where the speakers are placed. The ceiling is a typical 8' and I have tried numerous speakers. Any ideas or thoughts? EQ's need not apply.
madmax

unc2701

Absorption in all direct reflection points, diffusion elsewhere.

What's under the stairs? Can you stuff that entire space with insulation for a bass trap? It's possible that what you're hearing is trouble with the bass, not midrange being accentuated.

madmax

Under the stairs which go upstairs is drywalled with stairs going downward underneath. To the room it just looks like a wall.

It is in the midrange area for sure. Sounds like taking the middle 3 knobs of a graphic EQ and setting them very high.

pearsall001

Hey, madmax. I've been singing this song for awhile now...that the room is by far the most important factor in achieving superb sound. You can switch out amps, preamps, source players, speakers, cables, yadda, yadda, yadda till the cow's come home. If you don't have the room under control then you're only just spinning your wheels.

I personally have stuff from: GIK Acoustics, Echobusters, Aurelex, ATS Acoustics, Acoustical Solutions, & Sonex. The difference in sound quality is staggering to say the least. I have a mix of bass traps, corner traps, & absorption panels. My next move is to pick up some diffusion panels. It only keeps getting better.

Here's some of the sites to take a look at. Email them also, they're all very helpful. This should keep you busy for awhile. Good luck!!! It's worth it!

http://www.gikacoustics.com/
http://www.atsacoustics.com/
http://www.echobusters.com/
http://www.acousticalsolutions.com/
http://www.rivesaudio.com/
http://www.auralexelite.com/
http://www.realtraps.com/
http://www.eighthnerve.com/
http://www.acousticsciences.com/
http://www.sonex-online.com/

Face

If you're handy, you can make them yourself.

pearsall001

Face wrote: »

If you're handy, you can make them yourself.

Some things a DIY project is suitable, but a lot of the stuff is well beyond DIY. It does get pretty technical. I'd much rather purchase from the pros & know what to expect. A lot of the DIY stuff might look good but doesn't really stack up to the pro stuff.

jm1

The root cause of all your performance difficulties arises from the muddle of tubes in your system. Cleaning house may self correct this and all future issues you may encounter.


You do not specifically state this, but from your post I suspect your system now resides in a different room than you were previously accustomed to.

Room modes are generally not an issue in that frequency band as the frequency wave length is too short. If you were having problems below 300Hz (for your room), that can be directly correlated to a room mode issue. I suspect there are other issues in these lower regions you are not aware of.

Each room imposes its own specific sonic signature on what you ultimately hear. Most acoustic experts attribute the room’s sonic contribution to 50% of what you hear. Some suggest that it is even more.

If your system was previously in another room, you may still be accustomed to that room’s sonic signature. In this room, the system would sound different as the room is now imposing a new set of sonic characteristics to the overall presentation you hear.

You need to plot the overall frequency response of your system in this room with a series of test tones. You may find that anomalies in the lower frequency bands are affecting what you are perceiving in the other frequency bands.

I also strongly suggest an installation of broad band acoustic treatments for the entire room. This will start to reduce the contribution of the room’s sonic signature from what you hear. You may find this takes your system to an entirely new level of performance and enjoyment.

JM

You can download an Room Mode Calculator from the Harmon International site. Click on 'White Papers', then 'Calculators' and select 'Room Mode Calculator' to download an XLS spreadsheet.

jm1

pearsall001 wrote: »

Some things a DIY project is suitable, but a lot of the stuff is well beyond DIY. It does get pretty technical. I'd much rather purchase from the pros & know what to expect. A lot of the DIY stuff might look good but doesn't really stack up to the pro stuff.

These were a significant pain in the butt to complete, but well worth the effort.

http://www.polkaudio.com/forums/showthread.php?t=23371
http://www.polkaudio.com/forums/showthread.php?t=45742

madmax

Great info guys. Now to wade through it all. I will do a frequency sweep next weekend hopefully. Its the same room and I've known of this problem for quite some time. I have recently moved the room around thinking the problem would go away, it didn't.

reeltrouble1

I would just buy some more gear and forget about it. You can look for gear to balance the sound for your ears, lets face it, your going to end up with alot of great gear, so its win win. Did I mention your going to get more gear, no brainer. Maybe the big Manley amps are too much considering how sensitive your speaks are. So you cant get the gain right, you need the 300b.

After that I would build a new room, for the gear of course.

RT1

madmax

I may be done with gear. New room would be nice though.
madmax

hearingimpared

I make my son & wife move around the room until the music sounds dead on. Then I place the dog where I think the bass hump is and then I'm good to go.

madmax

Success! Well, I found the problem at least. Ceiling reflections are causing my problems. I took two pieces of sonex foam and made an umbrella over the top of each speaker preventing sounds from heading to the ceiling and the huge midrange bump went away completely. Now I need to find the proper place on the ceiling to attach the foam to. I know I can play around with foam placement but its just so tough to keep repositioning on the ceiling. Is there some standard formula or practice on where to put it?
madmax

unc2701

Sit in your listening position, take a nerf ball and chuck it at the ceiling... the spot where it bounces off the ceiling and hits your speakers is the right spot Confirm by tacking a small mirror there and you should see your speakers in it when you sit in the listening position.

tcrossma

unc2701 wrote: »

Sit in your listening position, take a nerf ball and chuck it at the ceiling... the spot where it bounces off the ceiling and hits your speakers is the right spot Confirm by tacking a small mirror there and you should see your speakers in it when you sit in the listening position.

The nerf ball approach is no good because you might throw it with spin and change the trajectory... i'd stick with the mirror

fumoffu

This would be treating a first reflection. You need a helper and a mirror. Take a sit at your listening position, and have you helper place the mirror flat against the ceiling, then adjust the mirror's location until you see the speaker(s). This is where you will want to treat, it's the first reflection on the ceiling of the sound. You may want to do the same thing with the sides too.

madmax

This is getting good with the mirrored ceilings and all.
madmax

jakelm

I guess light and sound reflect the same way???

Wouldnt work for me. I would just put the mirror where I can see myself:p

Ricardo

I got great advice from GIKacoustics; gave them all the room data and they suggested what treatments to put where. I did buy from them, but you could just get the tips and put up some foam or DIY panels.

unc2701

tcrossma wrote: »

The nerf ball approach is no good because you might throw it with spin and change the trajectory... i'd stick with the mirror

There probably isn't enough angular momentum and/or friction in a nerf ball to throw it off by that much

...Gravity would screw it up some though. Anyhow, it's an approximation and saves some time moving the mirror around. You can do it just as well w/ a tape measure & some geometry.

jakelm

Im not quite following this mirror theory. Sound waves travel in all directions. Just because you can see the speaker in the reflection, doesnt mean thats where the soundwaves will hit the surface. The waves could hit much higher or lower. They could not hit it at all, from diflection of other objects in the room. They could also not hit, because they were cancelled out, by thier own waves.

Like I said, I dont understand this mirror thing. Or I could just be missing something here.

madmax

I was thinking a piece of aluminum foil on the ceiling in the approximate area, sitting in the listening area and pointing a laser pointer at the foil until I see it hit the driver.

unc2701

It's the most direct first order reflection and it's not like you're putting a driver-size piece of absorption there. The mirror is just a quick way to identify where that big reflection point is- Ideally, you'd treat in 360 degrees where those reflections occur, then add diffusion in other spots. Too much absorption and the room sounds "Dead".

tcrossma

Is there any easy way to experiment with room treatments with stuff that someone might have lying around the house? What can I stick on the ceiling temporarily just to see if I can make improvements? If I know treating my room will make a substantial improvement i'd then look at buying some products.

Could I tape some pillows to the ceiling/walls or something? What does everyone else do to experiment before going out and spending money on treatments?

jakelm

throw rugs. Hang on wall. Smaller ones like you put in front of the bath tub.

tcrossma

jakelm wrote: »

throw rugs. Hang on wall. Smaller ones like you put in front of the bath tub.

Great, that's easy enough. Thanks.

fumoffu

Yeah high-school geometry!

I drew some triangle and did some angle side angle angle stuff. And it turns out that if your ears are the same height as your speakers. Then the ceiling reflection point is going to be the middle! No need for mirrors on the ceiling... Well unless its for esthetics.

tryrrthg

A simple 2'x4' wood frame filled with fiberglass batt insulation and covered in burlap fabric will do the trick VERY nicely and be relatively inexpensive.

Same thing, only floor to ceiling in the corners makes a nice bass trap. I got great results doing that.

http://www.ethanwiner.com/acoustics.html

http://www.angelfire.com/sports/RCcars/acoustic_panels.htm

madmax

unc2701 wrote: »

then add diffusion in other spots.

How do I know which/how many "other spots" should have diffusion added?
madmax

unc2701

Diffusion generally goes everywhere behind the listening position, but it's a matter of taste. I clap my hands and listen to the decay, but it's hard to describe what it is you want to listen to. Search the web, I think I've heard of some tools that measure the reverb in the room and there's some "ideal" level that you should aim for.