AudioCircle
Audio/Video Gear and Systems => The Acoustics Circle => Topic started by: DTB300 on 7 Jan 2013, 07:21 pm
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Would be interested in others experience with diffusion at the 1st reflection points. Just spent the last hour searching and reading but could not find much. I plan to play around with this, but only have QRD's at my disposal.
- Did you use something like a QRD and did you find it worked better with the wells horizontal or vertical?
- Did you use something like a Skyline (2D) diffusor and find you liked that better than a QRD?
For the industry people (GIK, Real Traps, etc.) what do you usually recommend for product at orientation? I mostly see QRD's recommended during my search.
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We use them at reflection points all the time. We did it at RMAF this year also. It can work very well if the off axis power response of your speakers is good. QRD's oriented vertically will scatter front to back in the room and give a very nice spacious feel to the room and expand the soundstage.
Bryan
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Hi Bryan,wondering also in those same rooms at the first reflection points did you try the 242's,244's before the diffusers or vise versa.
Also what were your findings say like with 242's more focus with the instruments or maybe the diffusers made alot more stage envelopment with a perhaps a smidge loss of focus.
Just curious what you found doing both ways in the same room(s)THX.
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Absorption does tend to tighten and focus things more than diffusion and also works over a larger portion of the audio spectrum. If the off axis response isn't great absorption is the way to go certainly. No sense in scattering an unbalanced response.
DIffusion is just different in that it leaves all of the energy in tact but scatters it both in space and in time fooling your ear into thinking the information is coming from farther away.
Bryan
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Seems my 50a's have good off axis response :thumb:,perhaps an experiment with the gridfusor stacked might be a cheaper way as a test to see(hear the difference).
Then we can shell out mo money for the pricier QRD's :green:.
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We use them at reflection points all the time. We did it at RMAF this year also. It can work very well if the off axis power response of your speakers is good. QRD's oriented vertically will scatter front to back in the room and give a very nice spacious feel to the room and expand the soundstage.
Bryan...thanks.
I will have to try vertical to see how it sounds. I seem to see as many horizontal photos as well as vertical - I guess like anything in this hobby one just needs to try and see which they like better.
Right now I have 242's at first reflection but have some 2x2 QRD's sitting in a closet waiting to be used :)
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Vertical (diffusing horizontally) QRD with 9" maximum well depth here. In my situation, they work as well as absorption (Real Trap) to reduce smear but does not damp any energy and renders the room more lively. Makes the sound more like Strathmore than TKC Opera House. I love Strathmore. I was told that you need some room for diffusion to work. Since it works for me, I would think your room should be wide enough for diffusion to work at the reflection points although I don't know how well it would work with 'stats.
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Gentleman, will egg separators work? I read somewhere that they will but I don't imagine to the degree of a well engineered product. I have 242's on my side walls but would love to try diffusors instead. The thing is, they have to be rather deep (right?) in which case they will surely be mighty prominent fixtures in my smallish room. Any DIY ideas? Thanks.
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We use them at reflection points all the time. We did it at RMAF this year also. It can work very well if the off axis power response of your speakers is good. QRD's oriented vertically will scatter front to back in the room and give a very nice spacious feel to the room and expand the soundstage.
Bryan
Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.
Diffusion and constant directivity horns...yummy!
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Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.
Diffusion and constant directivity horns...yummy!
What would you choose for the first reflection with directional electrostatics (Sanders Sound Systems)?
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Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.
My speakers are very close to the side walls (by design) and therefore close to the dffusors. The diffusors still makes a difference. Not sure if it is theoretically optimal, but they do add ambience amd stability to the sound field.
I like the verticle QRD idea. I was thinking about trying a set of those GIK QRDs, one each on the inner side (L,R) of each speaker.
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What would you choose for the first reflection with directional electrostatics (Sanders Sound Systems)?
Somebody will likely do a better job of replying to your query than me. Flat electrostat panels are highly directional, right? So, what's to diffuse except the wall or corner directly behind them? I'm wondering if, say, three columns were placed directly behind them. Could something like that be beneficial?
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Good thread.
I have panels on first reflection points....walls and ceiling...and a QRD behind.
These are dipoles....Have often wondered if QRD on side walls would improve,
so I'll give it a try......but what about first reflection on ceiling? and what way would you
orientate that one? My set up in Avatar.
Thanks for opinions.
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Somebody will likely do a better job of replying to your query than me. Flat electrostat panels are highly directional, right?
Correct.
So, what's to diffuse except the wall or corner directly behind them? I'm wondering if, say, three columns were placed directly behind them. Could something like that be beneficial?
With ML speakers they have a 30 degree arc to them so they have more of a horizontal dispersion, so first reflection points are based off this dispersion Vertically, items like ceiling and floors are not as a big an issue.
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Have to be careful though...if your speakers are close to the side walls the angle the sound hits them from can be quite steep which can lead to the sound not going into the wells as it is meant to and performance being not as the diffuser designer intended. If your speakers are a ways out from the side wall it is better.
Diffusion and constant directivity horns...yummy!
Is this still true if using a 2D diffusor...something like a Skyline?
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Sure- the angles are still steep.
And just for clarity, something like the skyline is actually 3D and a typical QRD is 2D. 1 or 2 spatial and 1 time.
Bryan
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Sure- the angles are still steep.
And just for clarity, something like the skyline is actually 3D and a typical QRD is 2D. 1 or 2 spatial and 1 time.
Thanks for the clarification on 2D and 3D diffusion....
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(http://www.audiocircle.com/image.php?id=73572)
Gonna try these at my first reflections as an experiment,
These are SRL acoustic diffusors based on a prime 23,reminds me of GIK gridfusors.
I bought four for 200.00 and shipping to Alta Canada was only 62.00 :thumb:.
Hoping these might tell me what I like better absorption or diffusion at 1st reflections,I do have GIK 242's there now.
FUN,FUN,FUN.
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A quick way to mount/hang/etc. the diffusors is to use "T" pins and hook them onto the front of the 242's. Easy to move them up and down on the panel to find a spot which works best for you.
I tried this the other day, but like Bryan and others stated, I am too close to side walls. While it did offer a little more "air" around the sound, it just did not sound right. So I removed them and went back to absorption at 1st reflections. Fun time to try something new.
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Good idea,I'll try that.
I am also close to the side walls,but for a few dollars more(Clint Eastwood :lol:) to find out is not a biggie especially if we like what we hear.
don't know how a spaghetti western got in there.
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(http://www.audiocircle.com/image.php?id=73572)
Gonna try these at my first reflections as an experiment,
These are SRL acoustic diffusors based on a prime 23,reminds me of GIK gridfusors.
I bought four for 200.00 and shipping to Alta Canada was only 62.00 :thumb:.
Hoping these might tell me what I like better absorption or diffusion at 1st reflections,I do have GIK 242's there now.
FUN,FUN,FUN.
http://www.srlacoustics.com/grid-diffuser-qty-2/
is this your source?
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Correct
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"And just for clarity, something like the skyline is actually 3D and a typical QRD is 2D. 1 or 2 spatial and 1 time."
This is mistaken information based on my research. The typical QRD (typical refers to units such as the ones I manufacture, which Woodsyi and others employ in their rooms, that is with the wells oriented vertically) are known as 1D diffusers. The 2D units are also derived from QRD equations but have broad vertical as well as horizontal dispersion. They have the "skyline" appearance. For them to be as effective over a broad frequency range, the depth is greater than equivalent 1D diffusers.
On thing that can be done effectively is to use 1D diffusers in an array, such as two units stacked with horizontal wells flanked by 2 units with vertical wells. If you need broad vertical dispersion as well as horizontal, this is the way to go. This is usually only effective in large room acoustics (which also calls for large diffusers, please see website for examples.)
Allen Rumbaugh
srlacoustics.com
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A matter of semantics. I and many others consider time as a dimension.
Bryan
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(http://www.audiocircle.com/image.php?id=73572)
Gonna try these at my first reflections as an experiment,
These are SRL acoustic diffusors based on a prime 23,reminds me of GIK gridfusors.
I bought four for 200.00 and shipping to Alta Canada was only 62.00 :thumb:.
Hoping these might tell me what I like better absorption or diffusion at 1st reflections,I do have GIK 242's there now.
FUN,FUN,FUN.
Mitch, hi. Please follow-up here and give us a report. Thanks.
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Most definitely will.
This I enjoy as much as my music or gear.
Have lots of GIK bass trapping in corners, wall/ceiling,backwall ect.
Now I want to see what diffusion can do in my smallish room(since I know what absorption is doing). Don't mind spending a bit to find if perhaps I'll like diffusion better,then I'll know for me.
Hopefully it will give me more openness,we'll see,worth a shot.
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:thumb:
Most definitely will.
This I enjoy as much as my music or gear.
Have lots of GIK bass trapping in corners, wall/ceiling,backwall ect.
Now I want to see what diffusion can do in my smallish room(since I know what absorption is doing). Don't mind spending a bit to find if perhaps I'll like diffusion better,then I'll know for me.
Hopefully it will give me more openness,we'll see,worth a shot.
:thumb:
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Hey PDR
In my research and experience, a diffuser placed overhead the listening position is oriented with the wells going horizontally (Left to Right) in the room. This is consistent with what Schroeder himself did at Carnegie Hall, as well as John Storyk on his designs. We had tremendous luck with this orientation at Hilltop Studio in Nashville, this is a 8 foot wide 14.5 inches deep diffuser mounted in the ceiling grid.
(http://www.audiocircle.com/image.php?id=73591)
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Just to clarify, here is some information, for those interested in semantics......... Trevor Cox is considered one of the foremost authorities on acoustical diffusion technology.
http://www.rpginc.com/docs/Technology/White%20Papers/Acoustic%20Diffusers_The%20Good,%20The%20Bad%20and%20The%20Ugly.pdf
http://www.phy.mtu.edu/~suits/diffusers.html
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Here is even more information!
http://www.hunecke.de/en/knowledge/diffusors/qrd.html :D
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Due to my small room and my seating position - I am just at the outside edge of what we read/hear as proper distance from a diffusor 1ft for every 1" of depth. Currently my diffusors in the rear of the room are sitting in front of 4" absorption panels at ear height.
With this in mind, I think I will try out some BAD panels and see how they fare against an EPS Diffusor.
More reports later.....
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Just got my 4 SRL grid fusors today and for kicks put them in front of my 242's to see what might happen.
WOW I'm not sure as I was shocked at what I was hearing even on a few mediocre songs.
First off definitely closer to a live event than my panels,the stage grew big time,I don't know why but the bottom end got real punchy even on mediocre songs,and more space between the instruments on the stage with clarity.
It's almost as if the lead parts had more off the stage when it was their turn.
Having diffusion at the first reflection points for some reason reminded me of Magnepan 3.6's I had in here for a few weeks,something going on with the midrange.
Quite excited about this,but I'm going to do more listening tomorrow as it is quite a lot different than panels.
I like the panels 242's but this is quite a shocker musically.The 242's make a more focused presentation clean ect.
For sure early stages but what I'm hearing so far is what might be quite a step up and my speakers are 20"(C) from the sidewall and with the 242 and the SRL together is another 10"so I have 10" of space between the fusor and my speaker.
This so far is getting closer to live as far as I can tell,gonna be hard to sleep tonight as I'm just a bit excited,should be a lot calmer tomorrow,can't wait :thumb:.
Should add that my speakers are 8'apart and I sit 8'away.
The room is only 12X19X7
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I have been considering buying/making some panels for the frisst reflection points in my room which is almost identical in size. I'm anxious to hear more on your results over the next few days
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This so far is getting closer to live as far as I can tell,gonna be hard to sleep tonight as I'm just a bit excited,should be a lot calmer tomorrow,can't wait :thumb:.
This is great. I found almost the same type of results. Happy ratamacue!
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It might actually be more beneficial to keep the EPS diffusors in front of the absorbers instead of replacing them. This way you get mids & highs diffused, but get some low and low mid absorption to soak up standing waves. A sort of "best of both worlds" approach.
Of course, the 242 panels may also benefit more from being placed in a different area as well.
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It might actually be more beneficial to keep the EPS diffusors in front of the absorbers instead of replacing them. This way you get mids & highs diffused, but get some low and low mid absorption to soak up standing waves. A sort of "best of both worlds" approach. Of course, the 242 panels may also benefit more from being placed in a different area as well.
They work great in front of 242 and 244...depends on the amount of room you have. Like you said best of both worlds.
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It seems now that with the EPS diffusors(leaning on the 242's)that I get double the bottom end as in vol which I don't want.
Going to try to raise them up so they are the same height as the 242's to see if that helps,maybe because some of the diffusor is right inline where the woofers are on the 50a's9bottom two)
Other than that I like the diffusors there so hopefully I can fix the bottom end.
These SRL diffusors are 6"deep so either they are enhancing the bass or maybe (I hope)they need to be raised,will report back.
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We hear this all the time, that the bass needs to be reduced once the diffusion is placed. This can only mean that we are improving the presentation of bass in the room by breaking up standing waves, or acting as bass traps. These actions allow you to hear the bass more clearly, allowing a reduction in level. This is a good thing, not a bad thing. I was once ballyhooed around here for suggesting using diffusion at early reflection points (now it is apparently ok, since other manufacturers have endorsed it) , and have even endured more for suggesting large diffusers enhance bass. The control room pictured earlier in this thread had a specific bass standing wave problem which the large overhead diffuser fixed. I am sure that in the future I will be exonerated and proven right, as NWAA Labs in Santa Carita CA, the leading acoustical testing facility in the country, has verified my findings concerning bass frequencies and diffusion. He likened the action as the wells on large diffusers acting like hydraulic shock absorbers. My diffusers are made of solid material, and the larger ones have a low sub audio resonant frequency. I have felt it in my fingers when holding them in a room with full range material going. This is another way to enhance small and large room acoustics. It is certainly an exciting time we live in concerning the reproduction of sound and room acoustics!
Allen Rumbaugh
SRL Acoustics
www.srlacoustics.com
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I've tried a pair of the SRL prime 23 grid diffusors in two separate applications--in the large living-dining room main system and the far more compact bedroom system. Being multi-use, neither room is "dedicated" to audio, and each presents its own acoustic scaries, primarily reflections created by furniture placement and, in the main system, a massive ceramic-tiled fireplace approximately midway on the front wall behind the speaker plane.
In the 11' x 13' furniture-cramped and rear-corner-trapped bedroom, placement of a vertically-oriented diffusor atop a 28" speaker stand at the first reflection point on each side wall broadens and deepens the soundstage and enhances mid- and upper-bass definition and "slam." (The speakers are essentially standmounted mini-monitors, with no perceptible output below ~45-50 Hz, but there's still enough to generate a visceral Richter 8 if it's embedded in the program material.) The other benefit noted is greater detailing in the midrange and top.
In the 29' x 14' (shrunken to 12' at about 16' down the long wall) room--which has been tube-trapped where feasible--seating and other furniture placement precludes effective placement of treatment at the sidewall first reflection point, but after experimentation I've found that mounting a pair of vertically-oriented grid diffusors in a 4'W x 2'H wall atop the dining table (yeah, I know :lol:) about 5' aft of my listening position transforms the listening experience from "very good" with the best program material to "come on in and join us in the soundstage." Lateral imaging extends farther beyond the speaker boundaries than it does in the sans-diffusor configuration, space within the soundstage becomes far more corporeal, and, as a consequence, instrumental and vocal placement and dimensionality, as well as a more natural rendering of tonality, timbre, and previously "buried" nuance with decent-to-well-engineered program material, achieves "they're here" spookiness. Apologies if that sounds hyperbolic, but the sonic difference is that profound. Oh yeah, and the bass. With the diffusors in place, there's more and better-defined "rollout to and past the listener" of the initial bass drum whacks in the first movement of the Wild/Fiedler Gershwin "Concerto in F" collaboration on an RCA LSC--visceral to the nines. Remove the diffusors from the dining table (which I have to when we eat, or my wife won't make me any more chocolate whipped cream cake), and that it's-hitting-me-in-the-gut sensation disappears.
The point here is that in my situation, at least, the differences in listening venue characteristics and configurations mandated a different diffusion approach to each, and in each instance I achieved more than I expected.
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I've tried a pair of the SRL prime 23 grid diffusors in two separate applications . . . In the 29' x 14' (shrunken to 12' at about 16' down the long wall) room . . . seating and other furniture placement precludes effective placement of treatment at the sidewall first reflection point, but after experimentation I've found that mounting a pair of vertically-oriented grid diffusors in a 4'W x 2'H wall atop the dining table . . . about 5' aft of my listening position transforms the listening experience from "very good" with the best program material to "come on in and join us in the soundstage."
Very interesting. When your diffusor wall is in place, about how far is it from the wall behind you? The dimensions of my basement room (27' x 16') are similar to those of your living room/dining room and we similarly have a table (a pool table in our case) behind the listening position. It's 14 feet from the listening position to the back wall. Is this somewhat like how your room is laid out?
Thanks.
Dave
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Very interesting. When your diffusor wall is in place, about how far is it from the wall behind you? The dimensions of my basement room (27' x 16') are similar to those of your living room/dining room and we similarly have a table (a pool table in our case) behind the listening position. It's 14 feet from the listening position to the back wall. Is this somewhat like how your room is laid out?
Here's the layout (not to scale), Dave:
(http://www.audiocircle.com/image.php?id=75179)
My listening position is about 13.5' from the rear wall. Putting the diffusor 5' behind me sits it 8.5 feet ahead of the rear wall.
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My listening position is about 13.5' from the rear wall. Putting the diffusor 5' behind me sits it 8.5 feet ahead of the rear wall.
Jim,
Thanks SO much! That is just what I needed to know -- it seems that our rooms and set-ups are similar. I'm going to try what you've done, both behind the listening position and at the first reflection points. Thanks again!
Dave
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You're welcome, Dave. Let us know how it turns out, especially which configuration works best for you.
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Can the SRL grid diffusers be placed side x side (horizontally) when in a vertically-oriented grid position, if one is flipped 180 degrees?
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Can the SRL grid diffusers be placed side x side (horizontally) when in a vertically-oriented grid position, if one is flipped 180 degrees?
Allen may want to comment on this, but because there's a fairly shallow-depth lip on both sides in the vertical orientation to allow for drop-in into a ceiling grid, the horizontally-oriented diffuser won't stand on its own in a standalone configuration (like the one I employ atop my dining table or atop speaker stands in my bedroom system) absent attachment via adhesive to, say, a plywood back with protruding frame behind it to support it.
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Heres a diffusor that I dont think has ever been posted:
http://www.decware.com/newsite/room.html (http://www.decware.com/newsite/room.html) It can be purchased as a kit OR assembled. They sell the plans for 10 bux too! Maybe the plans could be adapted for a bigger/deeper diffusor?
~J
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Allen may want to comment on this, but because there's a fairly shallow-depth lip on both sides in the vertical orientation to allow for drop-in into a ceiling grid, the horizontally-oriented diffuser won't stand on its own in a standalone configuration (like the one I employ atop my dining table or atop speaker stands in my bedroom system) absent attachment via adhesive to, say, a plywood back with protruding frame behind it to support it.
Yes, I planned on adding a backer, in fact plan on installing them (including backers) on movable stands. If they are similar to the GIKs, then the lip can be trimmed off. My concern is performance. If I understand correctly, the GIK Gridfusors are already a paired/inverted set of QRDs, formed into one assembly. So they are recommended not to be placed as I described above.
The SRLs are slightly different on each end, so just wondering...
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I've tried and stuck with diffusion at the first side wall reflection point. This is despite the room being small and the speakers being located quite close to the side walls. Yes, there are some trade offs which I have observed and written about but overall it was my preference.
(http://www.audioenz.co.nz/forums/showthread.php/11492-Music-from-a-farther-room/page3[HERE[/url)