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Post by longscale on Nov 9, 2023 18:41:18 GMT -6
I learned to build my own broadband absorbers. I built a small number and was happy with the result. Then I decided more is better, and built a cloud to hang over my listening position. Now I wonder if I've gone too far.
Is there a simple formula one can use to rule of thumb it?
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Post by notneeson on Nov 10, 2023 10:24:03 GMT -6
I learned to build my own broadband absorbers. I built a small number and was happy with the result. Then I decided more is better, and built a cloud to hang over my listening position. Now I wonder if I've gone too far. Is there a simple formula one can use to rule of thumb it? I think, technically you would see lopsided decay times, with the high and upper mids falling off way before the low end in an over treated room. I went a bit too far— the frame of my room is filled with rockwool and covered in acoustic fabric rather than Sheetrock. Adding GIK Alpha panels (absorber/diffuser) really helped balance things back out. I do want to add a cloud eventually but translation is pretty decent as of now. |
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Post by longscale on Nov 10, 2023 12:04:09 GMT -6
The cloud in question was built from three 16" x 48" panels, that are 6" deep filled with rockwool. The cloud has a 5" air gap between it and the ceiling. The other absorbers in the room are the same 16 x 48 but are 3" deep. I used them to treat the first reflection points, behind the monitors and on the sides of the listening position. I don't have a ton of those (4 actually) in this room, but adding the cloud really changed the sound of the highs and upper mids. Initially that was very unsettling. Having lived with this setup for a few months now I'm used to the change. I do not notice any unbalanced lows vs highs, or imaging folding up (lack of depth in the sound). The initial shock of adding the cloud and how much it did make the front 1/3 of my room quite dead caused me to wonder if I went too far and should reduce the size of the cloud, or add some diffusion to the room. I worry that I compensate for that deadness with more reverb or ambiance (short delays) than is actually needed.
If I were to try and measure this with something like REW - would that help point out the lopsided decay times you mention? Or is there another tool/way to do that?
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Post by notneeson on Nov 10, 2023 15:21:13 GMT -6
The cloud in question was built from three 16" x 48" panels, that are 6" deep filled with rockwool. The cloud has a 5" air gap between it and the ceiling. The other absorbers in the room are the same 16 x 48 but are 3" deep. I used them to treat the first reflection points, behind the monitors and on the sides of the listening position. I don't have a ton of those (4 actually) in this room, but adding the cloud really changed the sound of the highs and upper mids. Initially that was very unsettling. Having lived with this setup for a few months now I'm used to the change. I do not notice any unbalanced lows vs highs, or imaging folding up (lack of depth in the sound). The initial shock of adding the cloud and how much it did make the front 1/3 of my room quite dead caused me to wonder if I went too far and should reduce the size of the cloud, or add some diffusion to the room. I worry that I compensate for that deadness with more reverb or ambiance (short delays) than is actually needed. If I were to try and measure this with something like REW - would that help point out the lopsided decay times you mention? Or is there another tool/way to do that? I’m far from an expert, but yes REW would reveal it, I imagine. Ideally you’d want to have before and after. Sounds like you made an improvement and had to get used to it. The wet/dry thing is always challenging. Particularly because on the client side it’s very subjective/taste based. That said, this is where adding back in some diffusers might help. I specifically went with the GIK design because they work in smaller rooms. Other diffuser types often need to be a critical distance from the listening area. |
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Post by Ward on Nov 11, 2023 13:33:32 GMT -6
See attached. Use this as your pattern. Build a grid so every square is 5" by 5"  Fill each space with foam rubber cut to different depths. 0 = 1/8" foam rubber, like almost a piece of upholstery 1 = 1/2" 2 = 1" 3 = 2" 4 = 3" Get all your pine or spruce for the frame from Home Depot, and the foam rubber in sheets from from Pro Audio LA, Case Builders or Trans Continental Hardware |
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Post by Ward on Nov 11, 2023 13:34:07 GMT -6
P.S. Instead of a cloud! A fractal diffusor on your ceiling.
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Post by notneeson on Nov 11, 2023 15:01:03 GMT -6
P.S. Instead of a cloud! A fractal diffusor on your ceiling. Nice! Ward what’s the effective distance needed for this design? |
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Post by Ward on Nov 11, 2023 18:48:14 GMT -6
P.S. Instead of a cloud! A fractal diffusor on your ceiling. Nice! Ward what’s the effective distance needed for this design? Anything over 7' works. 10' is where mine is. Ever been outside and heard the bounce off the sky or clouds? Me neither. This kind of absorbing fractal diffuser essentially removes the ceiling. |
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ericn
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Post by ericn on Nov 11, 2023 22:26:57 GMT -6
See attached. Use this as your pattern. Build a grid so every square is 5" by 5" View AttachmentFill each space with foam rubber cut to different depths. 0 = 1/8" foam rubber, like almost a piece of upholstery 1 = 1/2" 2 = 1" 3 = 2" 4 = 3" Get all your pine or spruce for the frame from Home Depot, and the foam rubber in sheets from from Pro Audio LA, Case Builders or Trans Continental Hardware Or use balsa wood, if you someone who can do vacuum molding it’s an awesome way to do it as well. Even better if stuff the back with insulation. Ward |
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Post by Ward on Nov 12, 2023 8:40:43 GMT -6
Or use balsa wood, if you someone who can do vacuum molding it’s an awesome way to do it as well. Even better if stuff the back with insulation. Interesting thoughts there, bruv! |
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Post by ericn on Nov 12, 2023 17:13:45 GMT -6
Or use balsa wood, if you someone who can do vacuum molding it’s an awesome way to do it as well. Even better if stuff the back with insulation. Interesting thoughts there, bruv! I have built way to many skylines over the years, RPG and a bunch of the others offer an expensive vacuum molded option, a client who’s father owned a plastic company saw one and decided to make his own. |
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Post by Ward on Nov 12, 2023 17:28:25 GMT -6
They aren't that hard to build!  |
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Post by ericn on Nov 24, 2023 14:01:16 GMT -6
The key is a well thought out jig, so it’s repetitive cuts rather than repetitive measurements. All those Sunday afternoons watching Norm Abraham’s taught me the value of jigs. Also a frame like this is much easier with a dado set. Of course if you have the $$$$ a CNC router is magic. |
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