Greetings,
I have several 2-inch thick OC 705 fabric-wrapped panels hanging from my studio ceiling, but I'd like to adjust their position for maximum high frequency absorbtion. (The room is too "live" as is.) To accomplish this, should the panels have some air space behind them, or should they be mounted directly to the ceiling? Which way would absorb the most high frequency energy? Thanks for your feedback.
705 panels, placement for best high freq absorbtion
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MapleGuitar
- Posts: 2
- Joined: Tue Oct 11, 2005 4:50 am
- Location: Central Pennsylvania
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knightfly
- Senior Member
- Posts: 6976
- Joined: Sun Mar 16, 2003 11:11 am
- Location: West Coast, USA
Maple, welcome; I know your question doesn't require this, but we have a board policy that generally helps us minimize the number of posts required to help people; it's here
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4062
I know you've missed it, or your location would be posted along with your user name. I'd appreciate it if you take care of that part at this time -
As to high frequency absorption, that won't change with or without spacing from the ceiling; the spacing causes absorption at LOWER frequencies to improve. While this is generally a GOOD thing (makes absorption more uniform) if you still have too much high frequency you will probably need more surface covered with absorption.
Way it works is this - lowest peak absorption occurs at 1/4 wavelength. Wavelength is = to speed of sound divided by frequency (If I knew your location, I'd know whether to use metric or english units - just one reason for that "read first" announcement) - since I don't know where you live, I'll use english units. Wavelength = 1130/frequency, so for 10 kHz tone the wavelength would be 1130/10,000 or .113 feet, or 1.356 inches. Divide this by 4 to get 1/4 wavelength, and you have maximum absorption of 10 kHz with only 1/3 inch of depth.
This is linear, so 1 inch would get you 3 times as low frequency, or 3.3 kHz, and 2 inches would get you down to about 1.6 kHz - this is just 1/4 wave length, actual absorption continues to be useful to at least an octave below that, or about 800 hZ for 2" absorption mounted against the wall or ceiling. Spacing the material off the wall does even more to lower this bottom end, but the only thing that will increase UPPER frequency absorption is MORE SURFACE AREA.
Only exception to this I can think of is if you've covered your absorbers with some sort of non-breathing material, such as plastic... Steve
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4062
I know you've missed it, or your location would be posted along with your user name. I'd appreciate it if you take care of that part at this time -
As to high frequency absorption, that won't change with or without spacing from the ceiling; the spacing causes absorption at LOWER frequencies to improve. While this is generally a GOOD thing (makes absorption more uniform) if you still have too much high frequency you will probably need more surface covered with absorption.
Way it works is this - lowest peak absorption occurs at 1/4 wavelength. Wavelength is = to speed of sound divided by frequency (If I knew your location, I'd know whether to use metric or english units - just one reason for that "read first" announcement) - since I don't know where you live, I'll use english units. Wavelength = 1130/frequency, so for 10 kHz tone the wavelength would be 1130/10,000 or .113 feet, or 1.356 inches. Divide this by 4 to get 1/4 wavelength, and you have maximum absorption of 10 kHz with only 1/3 inch of depth.
This is linear, so 1 inch would get you 3 times as low frequency, or 3.3 kHz, and 2 inches would get you down to about 1.6 kHz - this is just 1/4 wave length, actual absorption continues to be useful to at least an octave below that, or about 800 hZ for 2" absorption mounted against the wall or ceiling. Spacing the material off the wall does even more to lower this bottom end, but the only thing that will increase UPPER frequency absorption is MORE SURFACE AREA.
Only exception to this I can think of is if you've covered your absorbers with some sort of non-breathing material, such as plastic... Steve
Soooo, when a Musician dies, do they hear the white noise at the end of the tunnel??!? Hmmmm...
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MapleGuitar
- Posts: 2
- Joined: Tue Oct 11, 2005 4:50 am
- Location: Central Pennsylvania
Hi Steve, Thanks for the feedback. (Sorry I missed the profile requirement.)knightfly wrote:... if you still have too much high frequency you will probably need more surface covered with absorption.... the only thing that will increase UPPER frequency absorption is MORE SURFACE AREA...
So it sounds like the high frequency absorbtion is about the same whether the panels are suspended, as shown here, or glued directly to the ceiling.