[Big Red Machine]

I'll add that I added Prime 53's with 2" 703 behind to each side wall.  Lotsa dispersion.  And they're more than 12" deep.

[ted_b]

I recognize that diagram.   

George

. Yes, in full disclosure that diagram is from Ethans great Realtraps website.

[bpape]

If your tweet/mid is the same height as your ear, ceiling first reflection point should be half the distance to the speaker.

should the "baffles" of a diffuser be perpendicular to your line of sight or parallel?

Depends on how you primarily how you want to scatter it. 

Bryan

[satfrat]

My small room is 11'w x 17'L x 7'h with my speakers setup on the narrow width. I use Furutech diffusion panels at my 1st reflection points on both my walls and ceiling. I feel it has helped expand my soundstage depth greatly. I also use Eighth Nerve panels on all my ceiling & wall corner joints. My roon definitely doesn't sound like either a small room or an acoustically dead room. 
 
If I had a large room or a room with high ceilings, I would have probably looked more into absorption at the 1st reflection points and maybe diffusion on the front wall with the extra room. Can't really say tho as I've never been there. 
 
Cheers,
Robin

[MaxCast]

Pete,
you got a pic of those diffusers?....your gallery was a little intimidating to search 

did you buy or diy?

[Quiet Earth]

I'm using diffusion on the side walls, and yes, I like it more than absorption or bare walls. I never thought that they made the sound "brighter",  maybe more lively and more dynamic, but not brighter.

Diffusers need to be quite deep to reach the lower octaves, but shallow ones are better than not having any at all. I chose diffusers that are made of wood because I think that wood sounds better than plastic or other man made materials.  Everything has a sound to it, and diffusers do too. I know I'll probably get schooled for that comment, but I thought I would throw it in there anyway.  (The number you have dialed is no longer in service, please check your white papers and dial again.  .)


I don't know if I will ever get around to treating the ceilings. Maybe someday . . .

[tdangelo]

LOL.  Not hardly Pete.  Not my game.

My personal preference is absorption for lower ceilings, diffusion for higher ceilings with the caveat that it's still speaker and room dependent.  Diffusion on the ceiling can also help when you have hard floor surfaces and not just at reflection points.  If you want the illusion of more height (assuming a non-dipole/bipole speaker) is to use diffusion on other walls of the room besides the front and orient the fins horizontally so you induce more later reflections coming from the ceiling to trick the ear/brain into thinking the ceiling is higher.

The biggest problem with diffusion in lower ceilings is purely a matter of headroom.  To get a proper diffuser to function down to say around 500Hz, you're looking at something that's around 6" thick.  That's a tough sell to a lot of people who have 8' or less ceiling height (especially if you're as tall as Pete is!)

Bryan

thanks for the insite

[Big Red Machine]

Pete,
you got a pic of those diffusers?....your gallery was a little intimidating to search 

did you buy or diy?

Used QRdude and went a little crazy.

[MaxCast]

Pete, have you done a rta of your room?  It would be interesting to see the plots of your favorite absorption era and plots as you add more diffusion.

[Big Red Machine]

Pete, have you done a rta of your room?  It would be interesting to see the plots of your favorite absorption era and plots as you add more diffusion.

I don't have the gear to do it and not sure I could do it properly anyway.

Here's a construction photo of the back of one unit.  I actually like the sound of these.  The bass extends back behind me and the soundstage is wall to wall now.

[MaxCast]

thanks for the info.  I think diffusion is my next step.

[Big Red Machine]

I'm sure I could have achieved the same results with a smaller unit but I just chose the 53 because it fit the space.  I should have made a 47 or smaller and split them in half for easy handling.

I'll post a thread with the construction photos.

[Speedskater]

I was just reading a old review of a 2005/6 Toole talk.  He points out that you should not use too small diffusion units.

This has led to Toole’s recommendation that too many or too few reflections can be a problem. In particular, acoustic absorption, diffusion, and reflection must be broadband, ideally starting below 200Hz. He pointed out that the typical 1˝ or 2˝ sound panel most often affixed to walls works only at relatively high frequencies, and acts to effectively turn down the tweeter with no effect on the midrange or upper bass, thus unbalancing the sound.

[Big Red Machine]

I didn't mean a Prime 7, I meant a 37 or 47 versus a 53.

[eclein]

Hey..newbie question here..Big Red doesn't that area (shown directly under the number 5) make a kind of echo chamber, not the right words but isn't the space in there conducive to slap back echo of some sort..I'm curious as I initially thought diffusion was to totally break up the sound waves, I guess I'm thinking standing waves in that section....

[MaxCast]

Hey..newbie question here..Big Red doesn't that area (shown directly under the number 5) make a kind of echo chamber, not the right words but isn't the space in there conducive to slap back echo of some sort..I'm curious as I initially thought diffusion was to totally break up the sound waves, I guess I'm thinking standing waves in that section....

My guess is that if area 5 is centered between the speakers the first sound to arrive will be at an angle from the speaker and hit 2-3 sides before it exits back into the room.

[bpape]

And different frequencies will interact with the various widths in different ways.  Part of a QRD does in fact cause some 'absorption' via cancellations in the wells. 

Another way to build this would be to split it in the middle and move one end around so the deeper portion in the middle is now half on each end.

Bryan

[Ethan Winer]

Can one of our acoustics gurus comment on ceiling diffusion?  Does the the type of speaker impact its effectiveness?

Interesting thread, and sorry to miss this while I was away on vacation for a few days.

I don't have too much to add at this late date, but I encourage people to set up a controlled test if possible, to fairly compare absorption versus diffusion. I haven't done that for the ceiling reflection points in my living room HT because it's a pain with my high angled ceiling. But I did do a carefully controlled test at the side-walls, and absorption won there handily.

I assume that speakers having a narrow dispersion pattern are affected less by either absorption or diffusion. And of course speaker dispersion varies both horizontally and vertically. Speakers that don't send very much sound upward probably don't need anything on the ceiling.

--Ethan

[woodsyi]

Interesting thread, and sorry to miss this while I was away on vacation for a few days.

I don't have too much to add at this late date, but I encourage people to set up a controlled test if possible, to fairly compare absorption versus diffusion. I haven't done that for the ceiling reflection points in my living room HT because it's a pain with my high angled ceiling. But I did do a carefully controlled test at the side-walls, and absorption won there handily.

I assume that speakers having a narrow dispersion pattern are affected less by either absorption or diffusion. And of course speaker dispersion varies both horizontally and vertically. Speakers that don't send very much sound upward probably don't need anything on the ceiling.

--Ethan

Hello Ethan,

I don't know how you controlled your experiment but I am sure you used good empirical method for your test and that your result is valid.  But is it possible that other rooms can give different test result?  My personal observation (without measurement) is that not much changed in terms of overall sound stage depth or width when I went from your Micro panels to SRL diffusers on the side walls.  The initial placement of a diffuser on the back wall paid huge dividend in terms of establishing a solid sound stage with big depth.  The addition on the first reflection points on the side wall did not add anything. 

The difference is in the overall sound of music in the room.  I went with diffuser on the side wall to reduce refractive/reflective interference without sapping the overall tonality.  I think I get better decay characteristics with diffusers.  This may have something to do with the fact that I like the sound of acoustic instruments (including voice) in acoustically lively venues.  I don't like acoustic music in outdoor venues as much.  So I have a preference for certain interactive room sound.  I like tones to decay "naturally" and too much absorption, to me, deadens the lingering harmonics too quickly.  I am only saying this after I have filled the room with 10 of your absorbers and 4 from GIK.  I have also put acoustic tiles (absorption) on the drop ceiling (doubled on the ceiling reflection points) and stuffed the corners and edges above the ceiling with fiberglass batting. 

[ctviggen]

Hello Ethan,

I don't know how you controlled your experiment but I am sure you used good empirical method for your test and that your result is valid.  But is it possible that other rooms can give different test result?  My personal observation (without measurement) is that not much changed in terms of overall sound stage depth or width when I went from your Micro panels to SRL diffusers on the side walls.  The initial placement of a diffuser on the back wall paid huge dividend in terms of establishing a solid sound stage with big depth.  The addition on the first reflection points on the side wall did not add anything. 

The difference is in the overall sound of music in the room.  I went with diffuser on the side wall to reduce refractive interference without sapping the overall tonality.  I think I get better decay characteristics with diffusers.  This may have something to do with the fact that I like the sound of acoustic instruments (including voice) in acoustically lively venues.  I don't like acoustic music in outdoor venues as much.  I like tones to decay "naturally" and too much absorption, to me, deadens the lingering harmonics too quickly.  I am only saying this after I have filled the room with 10 of your absorbers and 4 from GIK.  I have also put acoustic tiles (absorption) on the drop ceiling (doubled on the ceiling reflection points) and stuffed the corners and edges above the ceiling with fiberglass batting.

I'm not sure a test using the Micro traps on the sidewalls versus diffusion would be that valid.  I'd use at least the normal traps, as these absorb more over the entire frequency range. 

I definitely think that one could over damp a room. 

I'd love to compare diffusion versus absorption.  Ethan, care to let me borrow some diffusers?