How many of you use diffusion at your first reflection points vs. absorption?

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Big Red Machine

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And is it giving more realistic sound, as in room filling?

woodsyi

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And is it giving more realistic sound, as in room filling?

I do and I get better decay and twinkle in my music like in a venue with live acoustics.

Addendum:  This is only after putting up a large diffuser at the back wall which really does most of the heavy lifting IMHO.

zybar

And is it giving more realistic sound, as in room filling?

I don't currently do this (I use Realtraps RFZ's at the first side reflection point), but I am considering putting up diffusion at my first reflection point on my ceiling.  A friend recently did this and I like the impact it is having.

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

BTW, I do use diffusion at the back of the room (behind me) and highly recommend it.

George

Big Red Machine

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I'm asking a little early because I have significantly increased my diffusion in the room but have only spent an hour listening half-critically.  But now I have diffusors on each side wall, behind the speakers, overhead, behind me on the thick absorber, and to the back sidewalls.

What I initially noticed was a room filling effect and an almost invisible soundstage width on the choruses but I still had excellent imaging on vocals and instrumentals.

Now I could have been in a bad way that one time but I also seemed to get a small headache as if it was too bright even though the volume was lower than I usually listen at.  Obviously I need to spend more time, but I am happy about the spaciousness but worried about the brightness.  Probably need to find the balance.

One thing that happened that never happened before was bass notes were more full bodied and some of them made me turn my head as they seemed to surround me which was pretty cool.

MaxCast

Pete, have you removed any absorption from your room with the addition of diffusers?
Try a thin blanket on the side diffusers for brightness, maybe.

bpape

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Diffusion at the ceiling points can be a really nice thing that will increase spaciousness without overly impacting imaging precision.

Whether or not it works well for you on the side walls will depend on whether you already have enough absorption to have the decay times balanced or not and whether the perceived increase in soundstage width is worth the tradeoff if you don't have the decay times right.

As for which speakers, if you have something that's relatively beamy vertically or has 'controlled vertical dispersion' like a line array, then it may not be as much benefit on the ceiling.

Bryan

tdangelo

would ceiling diffusion be as necessary/effective with a tall ceiling vs a lower ceiling?  My room averages about 12' with 14' peaks.

thanks
Tony

Big Red Machine

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Hey Tony!  I wouldn't think ceiling heights that high would see much benefit to your ears but Bryan will embarrass any answer I come up with anyway!

bpape

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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

woodsyi

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Yep, I got low drop ceiling.  So the absorption tiles were the way to go for me and I am not even tall. :thumb:

ctviggen

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Another issue is that you're closer to the diffuser and therefore the diffusion isn't as diffuse, if that makes sense.  For instance, my room has about a 7'8" ceiling, which is a full 4-6 feet shorter than Tony's room.  If you think of diffusion as a cone emanating from a single point, Tony is going to be at a location much farther from that point, meaning that the sound will be more diffuse.  For me, I'll be much closer to that point, meaning that the diffusion will be not as effective or ineffective. 

Or is the cone so big it doesn't matter?

bpape

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Over your head or behind you is a line that's parallel to the room dimensions.  For reflection points, even with a low ceiling, you're looking at more of an angled plain to make it easier to visualize.  That straight line distance from ears moving both forward and up is probably still far enough to be very usable.

Bryan

ctviggen

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How do you determine where to place the diffuser on the ceiling?  Using the mirror trick?  (Sit in your normal spot and have a helper move the mirror on the ceiling until you can see the tweeters/midrange of the speakers.)

BobRex

Use the mirror on the floor, then just translate the point to the ceiling.  If you have an 8 ft. ceiling and typical height speakers you won't be far off - less than a foot.  Or you could just do the math.

ted_b

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Here is the math.  For ceiling or floor just turn pic on it's side.  :)




ctviggen

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Hmmm....That makes sense because if x2=x1, then the reflection point would be y/2, which is correct. I'll have to work out the rest of the math some other time. 

zybar

Here is the math.  For ceiling or floor just turn pic on it's side.  :)



I recognize that diagram.   :wink:

George

woodsyi

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If you listen near-field and you have several vertical placements of drivers on your speakers, you might as well treat the whole ceiling between the speakers and you, which is not that much if you are using 2'x4' ceiling tiles.

bpape

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Correct. But, if your diffuser is only a couple inches thick, it's not going to do much below say a couple kHz so only the tweeter may be applicable.  If it's a deeper diffuser, then you'd want to address the midrange also.  As you get lower, the sound spreads more and acts less like a ray so there would be a larger area to cover.

Bryan

MaxCast

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?