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Post by johneppstein on Aug 31, 2019 12:20:16 GMT -6
a flat plat with holes is very much a diffuser. what do you think a binary amplitude diffuser is. putting a diffuser over an absorber doesnt stop the diffuser from being a diffuser and can actually enhance the absorber behind to absorb certain frequencies better. win win situation. Where do you get your (mis)information? I really hope it isn't Wikipedia.
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Post by johneppstein on Aug 31, 2019 12:29:45 GMT -6
Most of the stuff on the GIK page superficially resembles the "MLS diffusor" (which is a really crappy design for a diffusor anyway) but they're not that. The MLS uses adjacent strips of two different depths and varying width. Those GIK devices don't - they use a reflective plate but there's nothing behind it besides absorption - nothing to reflect. Therefore it's NOT a true diffusor, not even an MLS. And most of what I saw there doesn't really vary the width of the non-cutout areas of the plate which is vital to diffusion at multiple frequencies in that design.
Again, the ONLY real diffusor on that page is the "Evolution Polyfusor", which uses the variable radius of the curve to provide quasi-randomized scatter and the varying depth of the curved surface to make it work across a range of frequencies. The problem with that design is that it only provides scatter in the horizontal plane.
The Evolution model was the one in which I was interested. I suppose you could get scatter on both the horizontal and vertical planes, based on how you mount it, yes? IOW, mount one (or more) vertically; one (or more) horizontally. At a 90-degree angle to each other. Very interesting points of view and information; please keep it coming! TIA, -09 Well, yes you could in theory, but that type of diffusor is generally quite large - it has to be to work properly. Those things are 47.25" tall (about 4 feet), 24" (2 feet) across, and 5-1/4 inches thick. Nor exactly a little tile meant to be hung on the wall in patterns.
The fact that they're saying it's a bass trap makes me suspect that it's intended for corner mounting, which strikes me as a bit odd because diffusors are not generally mounted in corners. Bass traps are.
They do say they'll do shorter versions on special order but that would tend to compromise the bass trapping function AFAIK.
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Post by johneppstein on Aug 31, 2019 12:45:30 GMT -6
All i know is that I trust GIK very much, to my knowledge they are one of the few companies in the treatment business who are both knowledgable, extremely transparent and measure all their products in a scientific way which they post on their website. Write them an email, their support is second to none! I generally like GIK too, but everybody makes mistakes or gets weird ideas sometimes.
The thing is, treatment vendors who are basically "insulation pimps" (vendors of absorption) don't usually get much into diffusion because other than the polycylindrical type proper diffusors tend to be a bit complicated to mass produce and are often rather heavy and/or difficult to ship.
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Post by gouge on Aug 31, 2019 16:57:23 GMT -6
a flat plat with holes is very much a diffuser. what do you think a binary amplitude diffuser is. putting a diffuser over an absorber doesnt stop the diffuser from being a diffuser and can actually enhance the absorber behind to absorb certain frequencies better. win win situation. No. A flat plate with holes in a frame is a Helmholtz Resonator. again i dont agree with you.
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Post by johneppstein on Aug 31, 2019 17:18:44 GMT -6
No. A flat plate with holes in a frame is a Helmholtz Resonator. again i dont agree with you. Please see my response to the last time you said that.
And while you're at it you might pick up a copy of F. Alton Everest's "Master Handbook of Acoustics". And any of Phillip Newell's books on studio design.
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Post by gouge on Aug 31, 2019 17:28:50 GMT -6
a helmholtz resonator has one single hole.
what you are describing is a perforated panel absorber or a binary amplitude diffuser depending on design..
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Post by gouge on Sept 1, 2019 3:05:59 GMT -6
hi john have you read "acoustic absorbers and diffusers"
p.s. note the spelling.
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Post by Ward on Sept 1, 2019 18:38:00 GMT -6
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Post by gouge on Sept 1, 2019 22:41:18 GMT -6
id love to see john's designs too. after 30 years of study they must be very solid.
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Post by gouge on Sept 2, 2019 6:34:06 GMT -6
I've never really given the arqen diffuser much priority because in small rooms I really just don't think it's the right treatment. especially in a control room. that aside in bigger tracking rooms i'd give it much more thought. it's an interesting article though. did you read the entire document? here are some quotes from the last few paragraphs. "In addition to diffusion, all diffusers will exhibit a small amount of absorption"
"But absorption is not always a bad thing"
"An example is the thin, flat, BAD Panel by RPG (a 2D binary amplitude diffuser, or binary amplitude diffsorber). If you overlay the diffusion and absorption coefficient charts for the BAD Panel you will see a combination of diffusion and absorption between 1-2 kHz, and pure absorption below 1 kHz. "
kinda what I wrote earlier don't you think. Pity John exited the conversation. seems like a great way for him to improve his knowledge.
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Post by Omicron9 on Sept 3, 2019 9:13:49 GMT -6
Fascinating options and reading material. Part of me is more confused than ever, but still digging learning about diffusion and absorption. Thanks, everyone!
Regards, -09
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Post by Omicron9 on Sept 3, 2019 9:27:13 GMT -6
Incidentally, the word is properly spelled DIFFUSOR, not "diffuser".
It's a technical term.
Diffusor? I just met her! <hold for applause>
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Post by gouge on Sept 3, 2019 14:44:27 GMT -6
Fascinating options and reading material. Part of me is more confused than ever, but still digging learning about diffusion and absorption. Thanks, everyone! Regards, -09 to answer your first question. diffuser/absorber is really the only way to go in the average sized small control room.
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Post by gouge on Sept 3, 2019 14:50:26 GMT -6
in a tracking room again depending on size, and/or instruments recorded it's different which is why pro studios have more than one room.
maybe John can expand on those ideas
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Post by johneppstein on Sept 3, 2019 17:13:09 GMT -6
in a tracking room again depending on size, and/or instruments recorded it's different which is why pro studios have more than one room. maybe John can expand on those ideas Er, uh, no, I don't think so.
Pro multiroom studios have smaller rooms for mixdown and overdubs, and to accommodate clients on tight budgets who can't afford a full sized room (such as indie demo clients) or clients looking for "writing rooms". Given a choice without constraints I would never choose a smaller room over a large one for recording.
Some of the best large studios have variable acoustics, with rotating panels with two or three different types of surface. In a large room if you want isolation or a smaller "more intimate" environment you can use gobos.
To return to the topic of the thread, I can't recall ever hearing of a combination "diffusor/absorber" until now - I don't really see how such a thing could be constructed (and installed) without compromising one or both functions. For one thing, ideal positioning for a diffusor is not necessarily optimum for an absorber.
Frankly, the idea of a combo diffusor/absorber strikes me as something of a sales gimmick.
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Post by johneppstein on Sept 3, 2019 17:19:24 GMT -6
Fascinating options and reading material. Part of me is more confused than ever, but still digging learning about diffusion and absorption. Thanks, everyone! Regards, -09 to answer your first question. diffuser/absorber is really the only way to go in the average sized small control room. I'm not sure what you mean by an "average sized small control room". And I can't think of any case where I'd use a "combination diffusor/absorber" in any sort of small control room - you want your absorption placed in very specific posistions in such a room and those are NOT the same places you'd want your diffusion.
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Post by gouge on Sept 4, 2019 5:10:43 GMT -6
in a tracking room again depending on size, and/or instruments recorded it's different which is why pro studios have more than one room. maybe John can expand on those ideas Er, uh, no, I don't think so.
Pro multiroom studios have smaller rooms for mixdown and overdubs, and to accommodate clients on tight budgets who can't afford a full sized room (such as indie demo clients) or clients looking for "writing rooms". Given a choice without constraints I would never choose a smaller room over a large one for recording.
Some of the best large studios have variable acoustics, with rotating panels with two or three different types of surface. In a large room if you want isolation or a smaller "more intimate" environment you can use gobos.
To return to the topic of the thread, I can't recall ever hearing of a combination "diffusor/absorber" until now - I don't really see how such a thing could be constructed (and installed) without compromising one or both functions. For one thing, ideal positioning for a diffusor is not necessarily optimum for an absorber.
Frankly, the idea of a combo diffusor/absorber strikes me as something of a sales gimmick.
hmm. didn't you say you had studied this stuff for 30 years. Electrical audio is just one example of a studio featuring multiple rooms designed to achieve varying acoustic outcomes. there are many many others round the world. now returning to the topic at hand. didn't you say you'd read the master handbook of acoustics. because it's littered with absorber diffuser examples. the poly diffuser you liked at the beginning of this thread is in fact an absorber diffuser. chapter 9 of the master handbook of acoustics has details on polys. not to forget MLS, BAD etc. no they are not sales gimmicks.
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Post by gouge on Sept 4, 2019 5:22:29 GMT -6
to answer your first question. diffuser/absorber is really the only way to go in the average sized small control room. I'm not sure what you mean by an "average sized small control room". And I can't think of any case where I'd use a "combination diffusor/absorber" in any sort of small control room - you want your absorption placed in very specific posistions in such a room and those are NOT the same places you'd want your diffusion. well average sized these days is pretty small really. and because of that lack of volume theory tends to lean towards absorb everything below 250hz but maintain diffusion above 1k. if oyu have tried to design a small control room you'll quickly realize that once you deal with absorption there is no room left for diffusion so you end up having to combine the 2. honestly with every space I've ever designed, including bigger spaces like theatres and sports halls, the standard treatment included perforated absorbers which, as was discussed earlier are in part diffuser/absorber designs. even in small tracking rooms I've found perforated absorbers to sound excellent. there is a certain air to them. I've tried a lot of different solutions from battens to slats to full absorption and full diffusion and I have a fairly good feel for what I personally like. none of this is new. the bbc handbook provides examples of treatments from the 70's. the master handbook of acoustics etc all detail this stuff. more recently there is this example. myroom-acoustics.com/hosted/myroom-acoustics/MyRoom_Design-white_paper.pdf
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Post by johneppstein on Sept 4, 2019 12:15:41 GMT -6
Er, uh, no, I don't think so.
Pro multiroom studios have smaller rooms for mixdown and overdubs, and to accommodate clients on tight budgets who can't afford a full sized room (such as indie demo clients) or clients looking for "writing rooms". Given a choice without constraints I would never choose a smaller room over a large one for recording.
Some of the best large studios have variable acoustics, with rotating panels with two or three different types of surface. In a large room if you want isolation or a smaller "more intimate" environment you can use gobos.
To return to the topic of the thread, I can't recall ever hearing of a combination "diffusor/absorber" until now - I don't really see how such a thing could be constructed (and installed) without compromising one or both functions. For one thing, ideal positioning for a diffusor is not necessarily optimum for an absorber.
Frankly, the idea of a combo diffusor/absorber strikes me as something of a sales gimmick.
hmm. didn't you say you had studied this stuff for 30 years. Electrical audio is just one example of a studio featuring multiple rooms designed to achieve varying acoustic outcomes. there are many many others round the world. now returning to the topic at hand. didn't you say you'd read the master handbook of acoustics. because it's littered with absorber diffuser examples. the poly diffuser you liked at the beginning of this thread is in fact an absorber diffuser. chapter 9 of the master handbook of acoustics has details on polys. not to forget MLS, BAD etc. no they are not sales gimmicks. I didn't say I liked the polycylindrical diffusor, I said it was the only real diffusor I saw on that page. I also said that don't think much of poly diffusors. Or other one-dimesional diffusor types. I said I like hemispheric "skyline" style diffusors and the custom 2 dimensional diffusors I've seen on the walls of major studios.
I've never been to Electrical Audio, but don't they do a fair amount of work with groups on a tight budget that probably can't afford a large room?
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Post by johneppstein on Sept 4, 2019 12:29:45 GMT -6
I'm not sure what you mean by an "average sized small control room". And I can't think of any case where I'd use a "combination diffusor/absorber" in any sort of small control room - you want your absorption placed in very specific posistions in such a room and those are NOT the same places you'd want your diffusion. well average sized these days is pretty small really. and because of that lack of volume theory tends to lean towards absorb everything below 250hz but maintain diffusion above 1k. if oyu have tried to design a small control room you'll quickly realize that once you deal with absorption there is no room left for diffusion so you end up having to combine the 2. honestly with every space I've ever designed, including bigger spaces like theatres and sports halls, the standard treatment included perforated absorbers which, as was discussed earlier are in part diffuser/absorber designs. even in small tracking rooms I've found perforated absorbers to sound excellent. there is a certain air to them. I've tried a lot of different solutions from battens to slats to full absorption and full diffusion and I have a fairly good feel for what I personally like. none of this is new. the bbc handbook provides examples of treatments from the 70's. the master handbook of acoustics etc all detail this stuff. more recently there is this example. myroom-acoustics.com/hosted/myroom-acoustics/MyRoom_Design-white_paper.pdfPerforated absorbers are perfectly fine if well designed. They're Helmholtz resonators, which excel at dealing with narrow band resonances. They should, however, be designed and placed to fit the acoustics of the specific room. And they are not diffusors.
As far as "average size these days" being pretty small, those are studios that back in the day were known as "demo studios". Rooms that size are generally compromised in one way or another, often several. You can't avoid it when your room's too small. A lot of the "small studios" I've seen in recent years don't even have sufficient height for a real studio.
The design on page 6 of your paper is quite interesting and does in fact incorporate principles of both diffusion and absorption. It's also a custom build that bears no resemblance that I can see to the devices shown on the GIK page, or any readymade device that I've heard of (which is not to say that I've heard of everything.) It's also not a conventional perforated absorber
A minor error in that paper is that the room in question is not large enought to exhibit a true "RT60". Yes, the term is commonly misused these days, but still....
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Post by Deleted on Sept 4, 2019 14:13:03 GMT -6
hmm. didn't you say you had studied this stuff for 30 years. Electrical audio is just one example of a studio featuring multiple rooms designed to achieve varying acoustic outcomes. there are many many others round the world. now returning to the topic at hand. didn't you say you'd read the master handbook of acoustics. because it's littered with absorber diffuser examples. the poly diffuser you liked at the beginning of this thread is in fact an absorber diffuser. chapter 9 of the master handbook of acoustics has details on polys. not to forget MLS, BAD etc. no they are not sales gimmicks. I didn't say I liked the polycylindrical diffusor, I said it was the only real diffusor I saw on that page. I also said that don't think much of poly diffusors. Or other one-dimesional diffusor types. I said I like hemispheric "skyline" style diffusors and the custom 2 dimensional diffusors I've seen on the walls of major studios.
I've never been to Electrical Audio, but don't they do a fair amount of work with groups on a tight budget that probably can't afford a large room?
Studio B at Electrical is huge. Center Field room in Studio A is also large. I think a big thing with that spot is that bands with a tight budget can access a super high quality recording studio without exhausting their life savings. (sorry for going off topic)
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Post by gouge on Sept 4, 2019 14:57:43 GMT -6
the white paper is not mine john.
it was written by people with far more acoustic knowledge than myself.
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Post by gouge on Sept 4, 2019 15:01:28 GMT -6
well average sized these days is pretty small really. and because of that lack of volume theory tends to lean towards absorb everything below 250hz but maintain diffusion above 1k. if oyu have tried to design a small control room you'll quickly realize that once you deal with absorption there is no room left for diffusion so you end up having to combine the 2. honestly with every space I've ever designed, including bigger spaces like theatres and sports halls, the standard treatment included perforated absorbers which, as was discussed earlier are in part diffuser/absorber designs. even in small tracking rooms I've found perforated absorbers to sound excellent. there is a certain air to them. I've tried a lot of different solutions from battens to slats to full absorption and full diffusion and I have a fairly good feel for what I personally like. none of this is new. the bbc handbook provides examples of treatments from the 70's. the master handbook of acoustics etc all detail this stuff. more recently there is this example. myroom-acoustics.com/hosted/myroom-acoustics/MyRoom_Design-white_paper.pdfPerforated absorbers are perfectly fine if well designed. They're Helmholtz resonators, which excel at dealing with narrow band resonances. They should, however, be designed and placed to fit the acoustics of the specific room. And they are not diffusors.
As far as "average size these days" being pretty small, those are studios that back in the day were known as "demo studios". Rooms that size are generally compromised in one way or another, often several. You can't avoid it when your room's too small. A lot of the "small studios" I've seen in recent years don't even have sufficient height for a real studio.
The design on page 6 of your paper is quite interesting and does in fact incorporate principles of both diffusion and absorption. It's also a custom build that bears no resemblance that I can see to the devices shown on the GIK page, or any readymade device that I've heard of (which is not to say that I've heard of everything.) It's also not a conventional perforated absorber
A minor error in that paper is that the room in question is not large enought to exhibit a true "RT60". Yes, the term is commonly misused these days, but still....
if you read the handbook of acoustics you will see it says the opening of a helmholtz resonator produces diffusion
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Post by Deleted on Sept 4, 2019 15:28:49 GMT -6
My honest opinion: I ordered some GIK traps around 2006. When they came in, they looked a little more "homemade" than I expected. I thought the fit and finish could have been better. Their stuff looks way better now. I'm talking pure aesthetics. I decided to DIY the rest and eventually just sold the GIK's and replaced with all DIY absorbers and diffusers. I got really sick of the sound of 703 rigid fiberglass insulation. Sounds like having a sock over your ears or mixing in a coffin:) I ended up giving away about 30 bass traps to a couple buddies for free. I know this is not popular, but I tried switching to Audezee lcd-x (with my Lynx HILO's DAC and headphone amp) and only having one mono Auratone. I love it. Mostly mastering but also some mixing. I have not had one recall since I switched. Probably would not work for everyone doing it this way. I love having zero room sound. I even got used to M/S as at first that was the hardest part. If I was gonna use monitors again, I'd like a room like Mark Needham has. Just some big, open library w/high ceilings and no walls (reflection points) near the listening position. I'm not a fan of the sound of small heavily treated rooms personally. Those GIK on link look more like just absorbers...even if there is membrane in there. Check out the Canadian "Leanfusers" designed by Tim Perry. Those are easy awesome quadraphonic diffusers to DIY with free build plan online. arqen.com/sound-diffusers/gallery/
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Post by gouge on Sept 4, 2019 15:56:00 GMT -6
well average sized these days is pretty small really. and because of that lack of volume theory tends to lean towards absorb everything below 250hz but maintain diffusion above 1k. if oyu have tried to design a small control room you'll quickly realize that once you deal with absorption there is no room left for diffusion so you end up having to combine the 2. honestly with every space I've ever designed, including bigger spaces like theatres and sports halls, the standard treatment included perforated absorbers which, as was discussed earlier are in part diffuser/absorber designs. even in small tracking rooms I've found perforated absorbers to sound excellent. there is a certain air to them. I've tried a lot of different solutions from battens to slats to full absorption and full diffusion and I have a fairly good feel for what I personally like. none of this is new. the bbc handbook provides examples of treatments from the 70's. the master handbook of acoustics etc all detail this stuff. more recently there is this example. myroom-acoustics.com/hosted/myroom-acoustics/MyRoom_Design-white_paper.pdfPerforated absorbers are perfectly fine if well designed. They're Helmholtz resonators, which excel at dealing with narrow band resonances. They should, however, be designed and placed to fit the acoustics of the specific room.
again i dont agree. perforated absorbers can be narrow or broadband. they are generally broader than a helmholtz panel. additonally the perforated panel acts as a low pass which is another reason why they are used.
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