Room treatment advice needed...

[deilenberger]

Looking at them won't tell you anything. Make sure you see a chart that shows their absorptive coefficient by frequency. If they don't absorb decently between 20 and 200 hz., they aren't going to do you any good.

It seems a rather common design.. but was hoping someone had tried them and might have some comments. I'm a bit occupied with redoing the rest of the room which will cut into any time I'd have to roll my own.. so..

 

[deilenberger]

Found some info myself - the jury decision on the smaller foam traps - worthless.. http://redspade-audio.blogspot.com/2011/04/do-small-foam-traps-actually-work.html

Bummer. Guess it's off to find some OC-703 sheets, and try just placing it around in the corners and see what it does..

 

[beek]

Went looking for Android apps:

"FrequenSee" - free. Shows a simple o'scope type display from 0-20KHz. Price is right.

There is another one called "Spectral Audio Analyzer" - that one costs.. (or you can run a version that's limited to an 8KHz view). Does waterfall views.

Found "AndroSpectrum" which looks very complete ($6.95)

"AudioTool" ($6.99) Does dB meter, RT60 meter, spectrum analyzer, signal generator and polarity checker.

Also found "SoundForm" - (Free) - an audio signal generator for the Android. Offers White/pink noise, since wave, square wave, triangle wave, ramp and impulse.

Wonder if I can run SoundForm (output via the audio out jack) and one of the spectrum analyzers at the same time.. ? Unfortunately - nope. Can't do..

Another company, Radonsoft offers a spectrum analyzer (Free for 32 band, 40, 60, 120 on paid version), RTA Audio Analyzer that allows for calibration (temporary on free version, saved on paid version). $5.49. They also offer a program called "Noise Gen" which can create an WAV file of pink, white, sine sweeps (user selects duration) that can be burned to a CD, so I can create a test CD. Cool. The paid version of RTA is $5.49 (and lets you save sessions/info and all sorts of other neat stuff...)

I think I'm springing for this one.. will let you know how it works out. Meanwhile, off to bed, it's getting late..

Great let Us know, there seeems to be mixed opinion about over doing traps but in a small room it gets harder to over do. After you do this All your music will become new again. I was amazed with every change I made adding traps, I use ASC,Room Tunes,Acoustimac in 30 wide room that Had a hump from about 50-85 Hz. You will sense more detail in the bottom Octaves on first try.

 

[Brad225]

As a general rule foam doesn't make for good absorption. Try them and see but you will need alot of them to completly fill corners.

 

[beek]

As a general rule foam doesn't make for good absorption. Try them and see but you will need alot of them to completly fill corners.

Completely agree foam sheets mite be good for side
Wall reflections

 

[deilenberger]

Some measurements

I ended up buying the "RTA Audio Analyzer" (by Radonsoft) - looks to be a good tool, and I did some fiddling around. First I created 3 WAV files - using their tool - one pink-noise, one white-noise and one a frequency sweep.

I first did a calibration of the Android phone (and app) with just a quiet background. The application suggests using a pure pink-noise signal sent to the phone's microphone, but I haven't a clue how one would do this since it requires flat frequency response on the source of the pink noise (and that's what we're trying to achieve..) So - I just used the room itself, and waited until the calibration plot stopped changing.

Measurement of the room - quiet - nothing playing - as quiet as I can get it (after applying the calibration):



Normal volume measured at normal listening point:



Loud volume measured at normal listening point:



Softer volume measured at normal listening point:



Normal volume measured from the rear of the room:

​

Conclusions? (I'm not seeing a huge low frequency (bass) reinforcement or bump at the normal listening position. Perhaps a bit of one at the rear of the room..

Thoughts/comments welcome!

 

[beek]

I ended up buying the "RTA Audio Analyzer" (by Radonsoft) - looks to be a good tool, and I did some fiddling around. First I created 3 WAV files - using their tool - one pink-noise, one white-noise and one a frequency sweep.

I first did a calibration of the Android phone (and app) with just a quiet background. The application suggests using a pure pink-noise signal sent to the phone's microphone, but I haven't a clue how one would do this since it requires flat frequency response on the source of the pink noise (and that's what we're trying to achieve..) So - I just used the room itself, and waited until the calibration plot stopped changing.

Measurement of the room - quiet - nothing playing - as quiet as I can get it (after applying the calibration):
View attachment 15295


Normal volume measured at normal listening point:
View attachment 15293


Loud volume measured at normal listening point:
View attachment 15291


Softer volume measured at normal listening point:
View attachment 15292


Normal volume measured from the rear of the room:
View attachment 15294
​

Conclusions? (I'm not seeing a huge low frequency (bass) reinforcement or bump at the normal listening position. Perhaps a bit of one at the rear of the room..

Thoughts/comments welcome!

Wow I was gonna say thats the flattest non-treated room I have ever seen! Someting is up here maybe with what you are doing or the calibration.
Sit in the sweet spot & hold the unit at your adams apple towards the system.

 

[deilenberger]

Wow I was gonna say thats the flattest non-treated room I have ever seen! Someting is up here maybe with what you are doing or the calibration.
Sit in the sweet spot & hold the unit at your adams apple towards the system.

I was quite surprised also.

Well, I held the phone at my nose, and then I tried next to my left ear (while watching the screen.. ) With the microphone pointing right between the two speakers. Didn't make a huge difference when I moved it a bit.

Calibration was a question. Uncorrected - quiet noise (ie - nothing playing, just ambient noise - and it's a quiet room normally) shows the response curve of the phone to be somewhat high frequency biased. I'll have to take a capture. Nothing dramatic - probably a 25dB rise from 30-20KHz. The calibration takes that slope away. No big peaks or dips that I can see.

It actually sounds pretty good now. Unlike when I first set up the speakers - no real peaky bass notes.

I did add a rug under the desk - about 4'x6' - and in the little alcove by the garage door there are lots of coats and stuff hanging off one wall.. plus the doorknob on the closet door seems to have become the repository for about 4 fleece jackets (wonder how that happened?)

What I do find is the sound-stage isn't as wide as I'd like, or as well defined - but the speakers are only 6-7' feet apart, so that might be understandable. I think some damping on the side walls may help (there are bookcases on each wall - but at the moment they're empty, awaiting the room being painted.) That may also be a function of what I've been listening to - quite a few female vocal soloists with minimal instruments.. and mostly real (not electronic) instruments (mandolins, guitars and such.) Gotta dig out some full orchestral classic CDs..

Some calibration plots (just did these..):

Room background noise - uncalibrated:



This is the result of the calibration. It levels the curve (as would be expected):



And this is the background noise - with the calibration turned on:

​

Which looks almost identical to the result of the calibration (as might be expected also.)

It looks pretty good to me. The only hooks I can see in using background noise as the calibration source are:

1. Background noise is usually pretty much white noise - not pink. Dunno if that's good, bad or indifferent. It might account for the un-calibrated curve... on another app I tried - which didn't offer calibration - the "quiet room" curve had a similar shape.

2. Microphone response may be non-linear with volume, ie - as sound gets louder the curve may change. Again - dunno exactly how to determine this since it would require a pure totally flat source of white noise (I think) to determine this (or would we want pink noise?) How to generate that? Dunno, especially if we're using the same noise to determine the system/room response.

Thoughts are more then welcome.. meanwhile I'm not unhappy. As I think I mentioned early on - while the Sources are a few years old - they had about no use at all. The guy who owned them hooked them up once - didn't like them, went out and bought Klipshorns - put the Sources back in the boxes where they sat until I bought them. I think I'm actually breaking them in, and some of the initial tubby sound and peaky bass might have been due to them not being broken in yet.

Or not.. as I said - thoughts/suggestions are quite welcome.

My current plan is still to get some DC-703 sheets and play with them around the walls near the speakers and see if the sound-stage can be improved on. Might be as good as it's gonna get in this odd and small room, but worth playing.

 

[deilenberger]

I'll revise my comment about sound-stage and definition. Just put on Carmina Burana, Carl Orff. Atlantic Symphony Orchestra, Robert Shaw conducting. Telarc disk.. and it's wonderful. Can pick out individual voices and instruments. What a wonderful recording.. I'd forgotten just how good it is. And I'm hearing things I've never heard in it before..

 

[beek]

Do the mirror thing before U buy the stuff
Then do the walls at the mirror spots with somthing cheap like wool blankets if U got em in the house.

 

[beek]

By the way I Love Carmina Burana I mite have 7 or so diferent recordings

 

[beek]

Take a peek at these, I did see a rise at 50-60Hz on your chart

http://www.acoustimac.com/index.php/bass-traps/dmd-basstraps/dmd-bt4000-bass-traps-48x24x4.html#specs

Price isnt bad compared to ASC traps

 

[Bernard]

By the way I Love Carmina Burana I mite have 7 or so diferent recordings

I love Carmina Burana too, and have four recordings: Ozawa, Tilson-Thomas, Kegel, and Shaw. Which one is your favourite? I have heard it live too, a few times.

 

[beek]

I love Carmina Burana too, and have four recordings: Ozawa, Tilson-Thomas, Kegel, and Shaw. Which one is your favourite? I have heard it live too, a few times.

I recently saw a video performace of it (dont remem which) where I learned how they got that xlyophone effect by waving his hands over the bars after being first struct without touching them.......My fav is Tilson Thomas

 

[deilenberger]

One thing I may have forgotten to mention.. despite the ceiling in the room being low (about 7'8") - it also is an acoustic tile ceiling. Not the type hung from a metal frame - the kind of old 12"x12" tiles. The tiles on it were put there about 35 years ago by me.. and were considered top of the line at the time. The company still sells these incredibly enough. The surface of them is a swirl pattern (think diffuser) with micro-perforations into the rock-wool core which is about 1/2" thick. Above them are open 10" studs..

I never thought of these as having much effect, but.. might be part of the answer on why the room seems to be working.

For the 1st order reflections - at least for the ES panels - they're going to end up being where the bookcases are. Right now the bookcases are empty. Will be interesting to see how/if the sound changes when they're full of books. This is almost inspiring me to start painting..

 

[beek]

Stagger the book sizes & thicknesses

 

[deilenberger]

Stagger the book sizes & thicknesses

Bill - will do. I have been ignoring the system for a few days - paint work has started (wife is a slave driver - not giving me Saturday off of painting.. )

Don

 

[tonyc]

Deilenberger, check out Room Tunes. Cheap and effective.

 

[beek]

Deilenberger, check out Room Tunes. Cheap and effective.

Cant agree on the Room Tunes, save your money your better off with pretty Indian wool blankets on the side walls.
Room Tune does not publish Spec because there is none. There is no chance in hell that something that thin has any absorbent quality.
If its still out there find the Audio Critic's review of them He is not some fly by nite writer like most of them out there.