chris
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Posts: 16
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Post by chris on May 12, 2017 15:27:29 GMT
Question:
At what point do you get diminishing returns with 703 ridged fiberglass board ? I know the thicker the better but when money is involved, making all my absorption panels 8 inches thick of ridged fiberglass is super expensive. So at what point does layering another 2 inches on yield diminishing returns for cost? I can't find any tests that compare 8 inch 703 to 6 inch 703. I guess if we don't know (no data), I will just make them 6 with an air gap.
Ethan, are you still of the belief that making tuned traps are not worth the time?
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Post by Ethan Winer on May 12, 2017 16:17:00 GMT
Sorry, I've been in absentia lately. Yes, I still believe that broadband traps are better than tuned traps in nearly every situation.
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Post by Hexspa on May 13, 2017 3:42:44 GMT
Question:
At what point do you get diminishing returns with 703 ridged fiberglass board ? I know the thicker the better but when money is involved, making all my absorption panels 8 inches thick of ridged fiberglass is super expensive. So at what point does layering another 2 inches on yield diminishing returns for cost? I can't find any tests that compare 8 inch 703 to 6 inch 703. I guess if we don't know (no data), I will just make them 6 with an air gap.
Ethan, are you still of the belief that making tuned traps are not worth the time?
Chris, if you look at my "New Fluffy Panels" thread you'll see a comparison I did of 2x4" (8") rigid vs 4". Ethan has also conducted similar, more extensive, tests; I plan to add 1' fluffy to my series before long. You appear to get the most benefit by just adding, let's say, eight or nine panels to a room. The primary benefit in my room was from adding nine superchunks made from 23" fiberglass cut into wedges. Even the additional 20 4" panels only added incremental improvement. So, as it's been previously stated by rock, it's a law of diminishing returns. That's not to say that adding greater quantity or thickness (or gapping and FRK) has no effect - it's just about for what you're aiming. So ya, you're probably better off with a greater quantity over a greater thickness despite thicker panels having advantages - particularly in the 60Hz range from tests recently conducted in a 8x14.3x24.75 + room. -m
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chris
New Member
Posts: 16
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Post by chris on May 17, 2017 0:00:11 GMT
No worries, Ethan.
Alrighty, so my plan for this week is to get all ceiling tri corners treated along with the rest of the ceiling.
Here's what my plan is for the absorbers.
They will be hung clouds, made of 2'' 703 with 6.5 inch R19 on top of em, totaling 8'' 1/2 thick. There will be a total of 10 of them just on the ceiling tri corners, each panel is of course 2' X 4'.
a) What do you think of that for a broadband absorber (2'' 703 + 6'' 1/2 of R19)? b) My ceiling is 9ft so I'm thinking a 3'' 1/2 air gap?
Ethan, sound goes up, correct? Example: For treating bass frequencys if you could only treat either the ceiling tri-corners or floor tri corners, you'd treat the ceiling, right?
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Post by Hexspa on May 17, 2017 2:15:25 GMT
No worries, Ethan. Alrighty, so my plan for this week is to get all ceiling tri corners treated along with the rest of the ceiling. Here's what my plan is for the absorbers. They will be hung clouds, made of 2'' 703 with 6.5 inch R19 on top of em, totaling 8'' 1/2 thick. There will be a total of 10 of them just on the ceiling tri corners, each panel is of course 2' X 4'. a) What do you think of that for a broadband absorber (2'' 703 + 6'' 1/2 of R19)? b) My ceiling is 9ft so I'm thinking a 3'' 1/2 air gap? Ethan, sound goes up, correct? Example: For treating bass frequencys if you could only treat either the ceiling tri-corners or floor tri corners, you'd treat the ceiling, right? It's clear I'm far from being Ethan but... I remember The Man saying that sound, low frequencies in particular, more-or-less radiate as opposed to moving linearly; it's not like steam! A ceiling corner, all things being equal, is no different than a floor corner. The concern is manageability: floor space etc. Regarding rigid thickness: fluffy behind a panel is, as Ethan has estimated, only about 30% better than air. In other words, for your money, you might better off with a thicker rigid panel. I've yet to see first-hand the difference between fluffy and rigid in an identical form factor but obviously rigid is more effective inch-for-inch. Pretty much you'll want to get all your rigid panels in order before optimizing them with fluffy displacing your air gaps. An 8' ceiling has an axial mode at about 70Hz. Therefore 2' is the ideal distance at which to treat it. That means for 9' you'll want at least a 4-6" panel gapped 4x it's thickness. My last room had 4" gapped 3x and it cured 70Hz pretty well with four panels. Remember, if you're treating non-RFZ then the addition of FRK is reported to assist low-frequency effectiveness. Thanks, -m
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chris
New Member
Posts: 16
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Post by chris on May 18, 2017 19:41:02 GMT
A 16'' air gap? Wow, that might get in the way of overhead mic'ing. Can you link me to your reference?
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Post by Ethan Winer on May 18, 2017 20:00:16 GMT
A 16-inch gap is one of the standard absorption test methods, and it's typical for drop ceilings. But that doesn't mean you have to allocate so much space!
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chris
New Member
Posts: 16
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Post by chris on May 18, 2017 20:25:53 GMT
That's interesting. "But that doesn't mean you have to allocate so much space!" What are my other options?
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Post by Hexspa on May 20, 2017 18:11:19 GMT
That's interesting. "But that doesn't mean you have to allocate so much space!" What are my other options? Allocate less space. It's a sliding scale. From what I've seen, the more you gap, the more you add low frequency effectiveness with a slight sacrifice around 250Hz. I forget the exact curve. Just do what you can manage! All anyone can do is find the facts then weigh their options; unless you can discover new facts - then maybe you can weigh your money. -m
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Post by Ethan Winer on May 21, 2017 16:38:03 GMT
Yes, Hex nailed it: allocate less space. Though it's not as simple as bigger is always better. It also depends on the thickness of the material. So you can't use a half-inch fiberglass ceiling tile six feet from the wall and expect it to absorb 30 Hz. Here's the relevant section in my Acoustics FAQ, linked in the READ THIS FIRST sticky post of this forum: ethanwiner.com/acoustics.html#air%20gap
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Post by Hexspa on May 22, 2017 0:21:23 GMT
Though it's not as simple as bigger is always better. It also depends on the thickness of the material. So you can't use a half-inch fiberglass ceiling tile six feet from the wall and expect it to absorb 30 Hz. I also confirmed this in my most recent tests. I tried gapping super chunks 6' off the wall get a 1/4 wavelength of 42Hz. It didn't work how I expected. For that reason, I've been suggesting to think in terms of multiples: 1x - 4x max. Thanks, -m
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chris
New Member
Posts: 16
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Post by chris on May 23, 2017 15:39:59 GMT
Regardless, the bottom line for small rooms is approaching the holy grail of anechoic. Regarding this statement^ I couldn't agree more. This is the approach/criteria I've decided on for my One-Room-Studio.
My Treatment Plan: 6'' 703 with 16'' air gap across the ceiling. 6'' 703 with 4'' air gap in all corners. ALL Wall surface's will be treated with 2'' 703 from 16'' off the floor (to clear outlets) to ceiling. This is done to eliminate flutter echo, since all walls have a parallel. Additionally, I already have multiple 6'' 703 moveable gobo style absorbers that I can move around and place in floor corners where necessary. The room has wood flooring.
I thought about leaving the wall behind the drum kit bare or making a poly diffusor for it BUT given that the drums will have to be only 3' away from it, (from my understanding) it's better to have it fully treated with dense absorption.
This room is going to be dry but hopefully also TIGHT, which is the most you can ask for in a bedroom sized room, from my understanding?
I may add some wood slat's over select spots of the wall absorption if the room feels weird/too dead but I'm hoping I wont have to.
Of course I am open to critique of this plan/criteria
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Post by Hexspa on May 24, 2017 22:14:04 GMT
Regardless, the bottom line for small rooms is approaching the holy grail of anechoic. Regarding this statement^ I couldn't agree more. This is the approach/criteria I've decided on for my One-Room-Studio.
My Treatment Plan: ALL Wall surface's will be treated with 2'' 703 from 16'' off the floor (to clear outlets) to ceiling. This is done to eliminate flutter echo, since all walls have a parallel.
While I think it's good to go for max coverage, I want to propose an alternative to "all surfaces with 2"" First off, with a 2" panel you probably only want to gap it as much as 8". Again, I haven't tested this extensively but (preliminary measurements have confirmed) placing a thin panel far from a boundary isn't necessarily more beneficial than using a 1-4x gap. So, to control flutter echo and still absorb some lower frequencies, you can double the thickness of your proposed 2" panels and place them in an alternating "checkerboard-style" pattern along your walls. In other words, from front-to-back, one wall will get 2' (feet, not inches) wide of 4" panels (gapped 16" if you want) then the opposite wall, after 2' of nothing, will get 2' of panels etc. This will control flutter echo while maximizing coverage with the added benefit of absorbing to a lower frequency. I've implemented this strategy in my new room and, while having double-wall absorption is better, I am getting controlled reflections with the one-sided 2' span. I think it's misleading to only consider flutter echo as it's a mid-and-high frequency problem. Lower frequencies are still going to be subject to boundary interference and, though our ears are most sensitive between 2 and 4kHz, we need to address that - unless we're recording bird sounds etc. That's my feedback; hope it was helpful. Thanks, -m
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chris
New Member
Posts: 16
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Post by chris on May 24, 2017 22:55:03 GMT
Regarding this statement^ I couldn't agree more. This is the approach/criteria I've decided on for my One-Room-Studio.
My Treatment Plan: ALL Wall surface's will be treated with 2'' 703 from 16'' off the floor (to clear outlets) to ceiling. This is done to eliminate flutter echo, since all walls have a parallel.
While I think it's good to go for max coverage, I want to propose an alternative to "all surfaces with 2"" First off, with a 2" panel you probably only want to gap it as much as 8". Again, I haven't tested this extensively but (preliminary measurements have confirmed) placing a thin panel far from a boundary isn't necessarily more beneficial than using a 1-4x gap. So, to control flutter echo and still absorb some lower frequencies, you can double the thickness of your proposed 2" panels and place them in an alternating "checkerboard-style" pattern along your walls. In other words, from front-to-back, one wall will get 2' (feet, not inches) wide of 4" panels (gapped 16" if you want) then the opposite wall, after 2' of nothing, will get 2' of panels etc. This will control flutter echo while maximizing coverage with the added benefit of absorbing to a lower frequency. I've implemented this strategy in my new room and, while having double-wall absorption is better, I am getting controlled reflections with the one-sided 2' span. I think it's misleading to only consider flutter echo as it's a mid-and-high frequency problem. Lower frequencies are still going to be subject to boundary interference and, though our ears are most sensitive between 2 and 4kHz, we need to address that - unless we're recording bird sounds etc. That's my feedback; hope it was helpful. Thanks, -m That's true, that's another way to do it that I've thought about, and you're right it would aid in better low-mid absorption. My worry I have with going with the "checkerboard style" approach is for tracking, drums in particular. I believe it would be fine for mixing though. Over the past 15 years, the times that I tracke in a small room, based on experience you do not want any close boundary high frequency reflections that are super close to especially a drum kit when tracking. The super close proximity of the intruments to reflective hard boundary's didn't sound so great. To me this leads to a comb filtering type affect because of the close proximity to the wall. Prefered way of course is to add in some good high frequency reflections QRD Diffusion, spaced wood strips in front of absorption, or scattering. This is just my humble thoughts from my experience when working in many rooms small, big, pro, and totally not pro (haha). Another belief of mine is when it comes to recording in a small room, you want to try and "trick" the mic/listener into thinking the source was recorded in a large space. As far as I know a small room will never sound like a large room than the best you can do is eliminate what makes a small room sound like a small room as much as you can. I'm not sure how much tracking of live drums you've done but if you've ever recorded drums in a large live room, the way the drums sound in the overheads is pretty dead and you have to really listen for any room ambience. This is partly because there isn't any nearby reflective walls, which is a good thing imho, oh and cubic footage, design, treatment, ect... The mic is mostly capturing the source with little room effect. You'll always be able to add ambience via reverb but you cannot get rid of bad early straight reflections, microphones tell the truth and there's fixing it, no matter what you do post. However I could be wrong of course, I can't say I've recorded drums in a small room that was well treated broadband and had the checkerboard approach to wall reflections.
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Post by Hexspa on May 25, 2017 14:07:42 GMT
While I think it's good to go for max coverage, I want to propose an alternative to "all surfaces with 2"" First off, with a 2" panel you probably only want to gap it as much as 8". Again, I haven't tested this extensively but (preliminary measurements have confirmed) placing a thin panel far from a boundary isn't necessarily more beneficial than using a 1-4x gap. So, to control flutter echo and still absorb some lower frequencies, you can double the thickness of your proposed 2" panels and place them in an alternating "checkerboard-style" pattern along your walls. In other words, from front-to-back, one wall will get 2' (feet, not inches) wide of 4" panels (gapped 16" if you want) then the opposite wall, after 2' of nothing, will get 2' of panels etc. This will control flutter echo while maximizing coverage with the added benefit of absorbing to a lower frequency. I've implemented this strategy in my new room and, while having double-wall absorption is better, I am getting controlled reflections with the one-sided 2' span. I think it's misleading to only consider flutter echo as it's a mid-and-high frequency problem. Lower frequencies are still going to be subject to boundary interference and, though our ears are most sensitive between 2 and 4kHz, we need to address that - unless we're recording bird sounds etc. That's my feedback; hope it was helpful. Thanks, -m That's true, that's another way to do it that I've thought about, and you're right it would aid in better low-mid absorption. My worry I have with going with the "checkerboard style" approach is for tracking, drums in particular. I believe it would be fine for mixing though. Over the past 15 years, the times that I tracke in a small room, based on experience you do not want any close boundary high frequency reflections that are super close to especially a drum kit when tracking. The super close proximity of the intruments to reflective hard boundary's didn't sound so great. To me this leads to a comb filtering type affect because of the close proximity to the wall. Prefered way of course is to add in some good high frequency reflections QRD Diffusion, spaced wood strips in front of absorption, or scattering. This is just my humble thoughts from my experience when working in many rooms small, big, pro, and totally not pro (haha). Another belief of mine is when it comes to recording in a small room, you want to try and "trick" the mic/listener into thinking the source was recorded in a large space. As far as I know a small room will never sound like a large room than the best you can do is eliminate what makes a small room sound like a small room as much as you can. I'm not sure how much tracking of live drums you've done but if you've ever recorded drums in a large live room, the way the drums sound in the overheads is pretty dead and you have to really listen for any room ambience. This is partly because there isn't any nearby reflective walls, which is a good thing imho, oh and cubic footage, design, treatment, ect... The mic is mostly capturing the source with little room effect. You'll always be able to add ambience via reverb but you cannot get rid of bad early straight reflections, microphones tell the truth and there's fixing it, no matter what you do post. However I could be wrong of course, I can't say I've recorded drums in a small room that was well treated broadband and had the checkerboard approach to wall reflections. My recording experience is limited; definitely nothing to rely upon for this discussion. You can always try both approaches and see which works best. -m
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