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Room Treatment: Diffusion


SWL

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1 minute ago, SWL said:

Back wall.....GIK bass traps and broadband absorption. The window directly behind the seating is 11'x5' covered with heavy drapes.

More Gridfusors on the side walls.7c0a1b471ea215525a182f5be296b364.jpg

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Sweet.  I'll take the main chair on the left.  You control the gear, I'll just sit and listen, with a beverage anyway.  Unless something sounds like crap and I'll throw my worthless cents in.  Deal??

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Yeah, going to do some half rounds with my few panels that I built.  Upper positioning, 4 of them.  Want to enjoy that refracted sound.  Dispersion and diffusion are our friends. 
All the experiments I've done so far, the volume knob has stayed the same.....but with the diffusion in place, it sounds slightly louder. As if there is more sound coming from the soundstage in addition to much improved separation and focus.

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Just now, SWL said:

All the experiments I've done so far, the volume knob has stayed the same.....but with the diffusion in place, it sounds slightly louder. As if there is more sound coming from the soundstage in addition to much improved separation and focus.

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Yeah, I can tell in my listening space that some diffusion is needed.  When you've listened to audio for so many years it's like you can 'see' the trajectory lines of the bandwidth.  I'm listening to subpar gear at that.  Anything I can do to make it sound better....   Very cool setup and space by the way.

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About 12 years ago, I went all out with absorption from GIK Acoustics. It seemed then and still seems now that the majority of audio enthusiasts talk only about absorption and bass traps. Not much about diffusion.

I've wanted to try this out for years now. Kept putting it off and part of the reason was the expense of the pre-made wooden units. These polystyrene GridFusors are more affordable and only weigh.....well....practically nothing. They're like air and easy to install.

I wanted something that was engineered and didn't want to do something half assed if you know what I mean (trees, book cases etc.)

I've got a few more things to try but I gotta say......those two GridFusors I initially put in between the speakers on each side of the TV was the most influential.

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Interesting set up and very nice room. I'll be rearranging soon to similar distance listening and against the back wall due to the KHorns needing the long wall and i had already been researching diffusion panels. Everything i read recommended them on the back wall reflection point, but you're saying the opposite huh?  Maybe i won't need any after all.  Do the bass traps work well on the back wall? I've normally used them behind the speakers in the corners with short wall placement, but i suppose i can use mine on the back wall as well with similar sized square absorption panels like yours on the first reflection points to the inside of the speakers, and having heavy drapes to the outside of the speakers.  I'll have 1 thinner but long and wide panel left i can use directly in the middle under the tv horizontally, but does it have to be tweeter height? Wouldn't the tv be tweeter height with the taller KHorns and the reflections would happen there?

As far as diffusion, i've also recently read that 1 panel can do just as much for you over multiple, but again, that was back wall.  Do you have a link to the diffusion panels you use?

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I am hearing that especially for home theater applications, ceilings are a great place for diffusion. I am pretty sure the GridFusers were engineered to be installed in suspended ceiling grids. Seeing how light weight the GridFusers are, one experiment that would likely provide significant payoff would be to do some temp installs of the diffusers on various ceiling locations using painter tape, bluetac, command strips, etc. to hold them up on the ceiling during short trials. Once the location is dialed in, some matching paint and harware of your choice for permanent placement.

 

Another location to place diffusers that works in many spaces is at the point of first reflection. This allows one to place more absorbtion in other areas of the room without overdamping the entire space while still getting diffusion at locations that are easy to identify and more likely to give solid improvements. Alternating absorbtion and diffusion panels along the wall keeping each treatment type around 20%-25% each and total surface area 50%or less.

 

I also have been studying the field of psychcoacoustics recently. It is a far greater challenge to get diffusion right as opposed to absorbtion, so much so, that without sound science, math, measurements, and luck, typical diy approaches often will not have much success. Besides the fact diffusion solutions are much more expensive than absorbtion, the aesthetics in a home environment can add yet another challenge. All reasons we hear so little about the subject.

 

One more note to add. The experts are saying that for best results 10 feet or more is needed between listening position and diffuser placement with absolute minimums of 6 feet. For the space I am currently room treating now, these distances will likely mean diffusion will not work for me in there.

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From what I have read, it is my understanding and now confirmed by my own experience......that if you have a wall directly behind your listening position, you want absorption on that wall. Quite a bit of it.....and then put diffusion on the front and side walls but not at the reflection points. Absorption only at the first and secondary reflection points.

 

This threw me off at first, too......because the typical control/mixing room pictures show diffusion on the back wall. However, those back walls were several if not 10 feet or so behind the listening position.

 

The point was, to have both and make them work together. Experiment until you hear what sounds 'right'.

 

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Yeah, GIK advertises the GridFusors to work well inserting into an acoustic ceiling but can just as well be used anywhere else diffusion is needed. Bottom line is it is diffusion. Same concept, same design just a lighter weight material being used.

I'll have to buy a few more to experiment with them on the ceiling because as of right now I'm satisfied with how I'm hearing things. Much more lively sounding......clearer, more detailed and more focused. Seriously, I'm hearing more music like I have an additional pair of speakers in here.

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The diffusors I have on the side walls I'm not so sure they are doing anything. Maybe because they're less than 10 feet away?

Not sure but maybe I'll relocate them to the ceiling. Hmmm....1a0f9f8b8733e260f738d2fb536aa01a.jpg

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So I just cranked this sucker and to my surprise louder spl's don't seem to sound really any different than before the diffusion.

Maybe....in my room....loud spl's just dominate the room and room issues are less of a problem? I wouldn't think that was the case. If anything I would think that room problems would be more audible the louder you go....but I'm no expert by any means.....just fumbling through this by trial and error and hey, it's working.



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I'll bet that many ways will work.

  • A room that's too dead is oppressive.
  • Yet, in a former home, my Khorns were in an a tiny room, about 800 cu.ft., and my desk chair (listening chair) was inches from the back wall, so I covered most of that wall with 4" thick Sonex foam that was an effective absorber down to 400 Hz.  The higher part of the wall, where it could not reflect down on me, was plaster, and gave way into a loft, .  The rest of the room was covered with book shelves with about 1/2 absorption (books) and 1/2 diffusion (art objects).   Naturally, the Khorns had 4 feet unobstructed (wood) wall running to either side of their corners.  From my desk chair, it sounded great!  From the sides, one still got stereo, but the imaging was scrunched and bunched.
  • In my current home I have a 4,000 + cu.ft. room with a little less absorption, proportionally, and as much diffusion as we could manage.
  • Many studios have (had -- I haven't been in one for about 16 years) Live End Dead End (LEDE), typically with the wall behind the listener all diffusive, and the front wall all absorptive.  Some like it, some don't.
  • See Artto's Klipschorn room for Bonner type polycylindrical diffusors.  https://community.klipsch.com/index.php?/topic/19799-arttos-klipschorn-room/& 

 

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That seems like a good idea. Are you using long pins or needles to attach the light weight panels?
At first I started with two different types of two sided sticky tape. One was too sticky, the other not sticky enough. So I went to using some real skinny nails.....two per panel works pretty good.

Replaced the broadband absorption under the tv with two diffusion panels yesterday. Don't really notice any difference in sound. I stole them from the ones I had on the side walls.

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Normally they say seating right on a back wall is not good at all,  but with those large curtains I think you have that well covered, nice looking room. 

 

It may be hard to judge what all the defusers changed but I would bet if you removed then all at once it would be  huge difference, looking good.

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