[Zheeeem]

I have had some good luck using 2" acoustic foam.  But I was very specifically trying to deal with some upper midrange issues.

How to treat a room depends on lots of stuff, including the room itself and what issue(s) you're trying to deal with.

If you just want to experiment, I'd suggest buying a 6-pack of Owens Corning 703 in 48"x24"x2" size, and/or some 2" acoustic foam and playing around.  Doubling (or tripling) the 703 will improve bass absorption.  Just try a bunch of different placements and see what works and what doesn't.  (You can easily stick the foam squares up with Scotch 77 spray.)

The advantage of the 703 is that, should you find some nice spots for it on the walls, it's not too hard to frame it and cover it with fabric.

[Big Red Machine]

Stay away from foam and 77 glue.  You'll regret it when you ha]ve to remove the foam and the stuff is left sticking to the walls.  Ask me how I know this.  Stick with 703 framed panels hung on nails.

Wayner, the traps will help alleviate any standing waves you have which may be creating nulls, not eliminate the bass.

[charmerci]

Wayner,

Putting rubber isolation absorbers under the speakers stops the shelves from putting out their vibrations (as Frank said in the old Audio Basics.)

It's also hard to tell from the photo, but is that shelf well braced?

[oneinthepipe]

Not to hi-jack Wayners' thread, but I have a couple of questions, the answers of which might also be useful to Wayner.

BRM: How did you make the cylindrical bass trap?

bpape: Do you recommend diffusion in a small room?  My room is 190 square feet.  Also, are 1" thick closed-back OC 703 panels sufficiently thick for the first reflection points on the ceiling?  I have 2" panels everywhere else, but I am using (3) 1"  closed-back panels on the ceiling that were previously placed between some windows and open wooden blinds.

[Big Red Machine]

Those are some auction deal diffusors I picked up before Xmas.

[Wayner]

Yes, I have rubber footers under all of the speakers. There are 2 other pair on the same shelf that are not in the photo. The shelf could probably hold 1 ton, it ain't going anywhere. I do appreciate all the input. This is a good topic, lets keep'r going.

Wayner

[Bill]

A little off topic, but in the ballpark. If you have your speakers, say, 5' out from the wall, would it be best to have your equipment between the speakers, slightly behind the front plane of the speakers (as some acoustical experts say) as opposed to on the back wall. And I'm not talking about a floor to ceiling behemoth with every imaginable ancillary source, but maybe a turntable with preamp and a couple of mono amps behind the speakers.

Thanks, Bill

[oneinthepipe]

A little off topic, but in the ballpark. If you have your speakers, say, 5' out from the wall, would it be best to have your equipment between the speakers, slightly behind the front plane of the speakers (as some acoustical experts say) as opposed to on the back wall. And I'm not talking about a floor to ceiling behemoth with every imaginable ancillary source, but maybe a turntable with preamp and a couple of mono amps behind the speakers.

Thanks, Bill

Yes, especially with a turntable.  Also, if your amps are behind the speakers, you would assumedly need to run longer interconnects to the amps if your rack and preamp were on the back wall.

[bpape]

Not to hi-jack Wayners' thread, but I have a couple of questions, the answers of which might also be useful to Wayner.

BRM: How did you make the cylindrical bass trap?

bpape: Do you recommend diffusion in a small room?  My room is 190 square feet.  Also, are 1" thick closed-back OC 703 panels sufficiently thick for the first reflection points on the ceiling?  I have 2" panels everywhere else, but I am using (3) 1"  closed-back panels on the ceiling that were previously placed between some windows and open wooden blinds.

,

The 1" on the ceiling is better than nothing - though personally, I like diffusion at the ceiling reflections if it's allowable.

Diffusion in a small room is tough behind you and at reflections since space is at a premium, most of the treatments need to do broadband duty as much as possible.  There just isn't room for dedicated mid/high panels and broadband bass control without covering way too much of the wall surfaces.  Diffusion can be used at ceiling reflections, and also in the rear half of the room on the side walls and ceiling to keep the soundfield more lively but still minimize slap.

Bryan

[oneinthepipe]

Not to hi-jack Wayners' thread, but I have a couple of questions, the answers of which might also be useful to Wayner.

BRM: How did you make the cylindrical bass trap?

bpape: Do you recommend diffusion in a small room?  My room is 190 square feet.  Also, are 1" thick closed-back OC 703 panels sufficiently thick for the first reflection points on the ceiling?  I have 2" panels everywhere else, but I am using (3) 1"  closed-back panels on the ceiling that were previously placed between some windows and open wooden blinds.

,

The 1" on the ceiling is better than nothing - though personally, I like diffusion at the ceiling reflections if it's allowable.

Diffusion in a small room is tough behind you and at reflections since space is at a premium, most of the treatments need to do broadband duty as much as possible.  There just isn't room for dedicated mid/high panels and broadband bass control without covering way too much of the wall surfaces.  Diffusion can be used at ceiling reflections, and also in the rear half of the room on the side walls and ceiling to keep the soundfield more lively but still minimize slap.

Bryan

Bryan:

Thanks.  What do you recommend for diffusion for the ceiling?  Otherwise, I can easily get 2" or thicker panels for the ceiling and return the 1" panels to their previous duty.

[James Romeyn]

Bumps below 200 Hz caused by room modes can be somewhat tamed w/ huge amounts of OC703 rigid 2" fiberglass (small to medium amounts no; www.RealTraps.com summarize simply & directly that more is better).  I built a professional full-circumference soffit stuffed w/ much costly OC703 for this very reason; ASC equivalent value was $8k.   

The bad news, per personal experience (Duke LeJeune of AudioKineses can explain the reasons better than me, as can Dr. Earl Geddes & others), is the apparently recent discovery that reflectivity is utterly critical to proper bass reproduction regardless of room size & that absorption is extremely toxic to proper bass reproduction.  If you experienced the audible effect of employing absorption to flatten modes as I have & heard the alternative described below, me thinks you would never again recommend absorption as a solution for bass modes, because indeed it is as much a poison as it is a cure. 

Many large commercial music venues do indeed have absorptive panels, but they absorb only above 200 Hz & remain reflective below 200 Hz.  All large room modes are subsonic because of the quantity of the dimensions; this is why the designers of large rooms are never concerned about bass modes & never have to account for bass modes.  They are not audible. 

Reflectivity in the bass range + a complete lack of audible modes are the single greatest audible signatures differentiating live music from reproduced.  Live music is most often experienced in large rooms & reproduced music in small rooms.  The difference described above was first brought to my attention in the last few months.  It is the single greatest discovery I've ever made in audio after doing this for many decades.  It probably outstrips & outweighs in audible significance virtually everything else I ever learned about audio combined, except maybe the simple knowledge of how to listen & how to differentiate my taste & apply the proper weight to what matters in music reproduction.

EQ is another dead end for modes IMO, because it fixes a mode in one small static part of a room by simply pushing the problem to another point in the room.  EQ is a one-dimensional static cure for a three-dimensional dynamic phenomena.  I have personal experience employing EQ & it did not fix the modes to my satisfaction.   

Regarding taste, we all crave, weigh & hear different characteristics, explaining why there are hundreds of different choices in components & speakers.  But the more you learn about audio, the more certain you become that random, irregular bass modes are solely a curse to good reproduction (modes being differentiated from the normal & smooth rise of output in the bass range caused by boundaries equal to about 9 dB at 20 Hz relative to 100 Hz).       

Read it, digest it & weep.  That's what I did after investing a small fortune in a professional acoustic soffit.

The good news is that Duke, Dr. Earl Geddes & others seem to have found a way to achieve the glorious bass reproduction of large rooms in small rooms.  It's much less costly than absorption & works infinitely better than EQ.  It's also much more portable & easier to fit, install & relocate than absorption.  IMO Duke's $2500 SWARM provides, overall, equal to or better than the best bass performance I've ever auditioned, including legends such as the Infinity IRS III, $65k USD in late-'80, six 12" servo-controlled woofers per side in separate 7' tall rosewood towers.  I highly recommend investigating the SWARM as an apparent be-all end-all solution to any present & future bass modes. 

I owned mostly large floorstanding speakers for decades but in the past few years have been sold on the joy, pleasure, & audible advantage of standmount speakers.  The beauty in Duke's SWARM is that it is a perfect match for bass & dynamic-limited standmounts.  I'd bet the SWARM would blend seamlessly w/ any main speaker as long as the main speaker's output could be limited to above about 80 Hz.  Beyond, that, IMO no real or imagined so-called full-range speaker, unless it employed two or more floor-to-ceiling bass towers filled w/ many woofers, can flatten modes as succesfully as the SWARM.

The only other mode cancelling technique I know of that I have not experienced is the Helmholtz resonator, extremely large, not very portable & tuned to only one extremely narrow band; meaning almost completely irrelevent (to me) when compared to something like the SWARM.  The SWARM flattens modes w/ NO OTHER BAND-AID EMPLOYED & can be used in any room.  It does not remove reflectivity, absolutely vital in the bass range for proper reproduction (I know this is very anti-intuitive & it's absolutely true IMO).  It's as close to magic as I've found in this hobby & we all know how many times we've heard that promise lead to a dead end (no pun intended).

The best advice to prove what is being described is to visit a large room (theater, etc.) & listen carefully to the bass range.  Notice the liquid, "elastic" (in a good sense) quality of the bass & how it is absolutely seamlessly integrated into the soundfield of the rest of the music spectrum.  There is no distinction from the bass range on up.  Go directly home & listen & the difference will amaze you.

The SWARM puts the sound of large room bass in your small room at home.     

[Minn Mark]

I'm interested in hearing opinions or experience about the Synergistic Research Acoustic Art room treatment I have seen in recent TAS.   Also a link is included.   What's the current thought, something real or more 'snake oil'??

http://www.synergisticresearch.com/?p=195

Minn Mark

[bpape]

Thanks.  What do you recommend for diffusion for the ceiling?  Otherwise, I can easily get 2" or thicker panels for the ceiling and return the 1" panels to their previous duty.

There are several options.  If you have the height, check out the D1.  Very cost effective and is effective from the vocal range up to beyond 10kHz. 

Bryan

[oneinthepipe]

I'm interested in hearing opinions or experience about the Synergistic Research Acoustic Art room treatment I have seen in recent TAS.   Also a link is included.   What's the current thought, something real or more 'snake oil'??

http://www.synergisticresearch.com/?p=195

Minn Mark

You're kidding, right?

[oneinthepipe]

Thanks.  What do you recommend for diffusion for the ceiling?  Otherwise, I can easily get 2" or thicker panels for the ceiling and return the 1" panels to their previous duty.

There are several options.  If you have the height, check out the D1.  Very cost effective and is effective from the vocal range up to beyond 10kHz. 

Bryan

Bryan:

How much height do I need?  I only have 8' ceilings. 

Can the D1 be hung?  The absorption panels are hanging about 6" below the ceiling, which was needed, not only for absorption, but because there is a shallow operating light fixture on the ceiling.  If necessary, I can remove the light fixture.

[Minn Mark]

Guess I was thinking that, given the appropriate room treatment...I might be able to experience the 'wind' of a previous life.

My idea of room treatment usially involves finding just the right place for the bottle of Scotch, so as to enable easy access from multiple listemning positions.

[oneinthepipe]

Guess I was thinking that, given the appropriate room treatment...I might be able to experience the 'wind' of a previous life.

My idea of room treatment usially involves finding just the right place for the bottle of Scotch, so as to enable easy access from multiple listemning positions.

I thought you were joking, especially when you posted the link on this particular forum.  I remember seeing that product or something very similar on the AVA forum not too long ago.  I think that Frank started the thread.

Regarding the scotch, I think you are in good company.  Some here, I believe, find that several carefully placed empty scotch bottles, combined with partially filled glasses of scotch, provide excellent diffraction, and whether or not the results are measurable or psycho-acoustic, no one cares.   This theory, unlike Ted's experiences in Buddhist temples that he visited during his sabbatical, was rumored to have developed following the consumption of numerous bottles of Scotch.   

[avahifi]

Those little Acoustic Art dingleberrys?

There is neither enough mass or surface area with these to do anything useful with room acoustics if you are dealing in the real world of physics.

They may do something useful to somebody's bank account, and they are almost small enough to actually swallow and be real sugar pills.

Strongly not recommended here.

Frank Van Alstine

[mark funk]

                                     

[avahifi]

Again, my room treatment is the whole ceiling covered with the lowest cost 1" thick Sonix acoustical foam ($700 installed) and the entire walls covered with acoustic wallpaper ($800 installed).  The wallpaper is a bit more than one-eighth of an inch thick, made of dense fuzzy cloth and goes up like wallpaper.  It is available in a variety of colors and textures in premium wallpaper stores.

It turned my suburban "rec-room" hollow box sound into a quiet and very listenable room, where the noise disappears very well.  Before thumping on a wall with your knuckles gave a clank clank sound, after its a dull thud.

Strongly recommended.

Frank Van Alstine