Triple leaf - at what leaf spacings is it acceptable?

666666 · 29th March 2008, 05:45 AM

I might be forced into a "triple leaf" situation with a room build, but since the leaf spacings are very different, I'm wondering how bad the triple leaf effect will be? In most triple leaf examples published / posted, the leaves are quite close together and often equi-distant.

In my potential situation here, leaf one is about 6" away from leaf two, and leaf two is about 18" away from leaf three. In sum, the spacing between leaves 2 & 3 is three times the distance between leaves 1 & 2.

Am I looking at a serious triple leaf headache here, or are the different spacings, plus the rather wide 18" spacing between leaves 2 & 3, going to perhaps cut down on or eliminate the "triple leaf effect"?

Perhaps it will cause trouble only at very low frequencies? If so, any prediction on what frequency area might be a problem?

Finally, with "triple leaves", there must come a point where the negative effect of triple leaf drops to the point of not being a problem once you reach certain leaf spacings. To exaggerate my point, if leaf one was 12" from leaf 2, and leaf 2 was 15 feet away from leaf three, is this even still considered triple leaf??? Or is it considered double leaf that is 15' from another separate wall??? You see my point. So... at what distances of 3 leaves nullifies the triple leaf effect? If my situation still seems bad, perhaps if I increase the distance of leaf 2 and leaf 3 from 18" to 24" I'll be ok??? Or 36"? Or 48"? Or 8 feet?

I'd rather not get into more details of the situation I am facing right now since there are still too many variables at this point... may not even happen... but I'd like to discuss the triple leaf spacing issue anyway... I've always wondered about it.

gullfo · 29th March 2008, 04:00 PM

depends. in a voice-over studio on a 40 acre farm, its probably less of an issue than recording death metal bands in a room 2' from an ICU. 3rd leaf is generally bad, but not necessarily as bad as other choices. whichever is the least worst choice, pick that one, and live with the other.

bpape · 31st March 2008, 08:34 PM

The difference in your scenario and the one (extreme) that you postulated is that in the 2nd one, there would still only be 2 leaves between rooms. In your case, there will be 3. There will be a frequency where it becomes an issue. at 12" it'll be relatively low but still may be a problem depending on your situation.

Bryan

avare · 2nd April 2008, 09:01 PM

The frequency of the space is based upon the square root of the mass of walls and the space in between. The isolation of walls is based upon the the depth and mass. You put a leaf in between and you making two smaller mass-air-mass systems inter-connected and raising the frequency of resonance by half an octave.

With the system you are talking about, the single resonance of the greater distance will be two thirds of an octave below the smaller space. Not insignificant. It usually is considered insignificant with quadruple leaf systems between across the corridor hotel rooms.

More specifics are needed to give you good advice for you application. How thick are the current walls? How much are willing to spend to add mass? These are just starters.

Andre

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29th March 2008, 05:45 AM	#1
666666 Lives for gear Join Date: Jan 2005 Location: Long Island, NY Posts: 939	Triple leaf - at what leaf spacings is it acceptable? I might be forced into a "triple leaf" situation with a room build, but since the leaf spacings are very different, I'm wondering how bad the triple leaf effect will be? In most triple leaf examples published / posted, the leaves are quite close together and often equi-distant. In my potential situation here, leaf one is about 6" away from leaf two, and leaf two is about 18" away from leaf three. In sum, the spacing between leaves 2 & 3 is three times the distance between leaves 1 & 2. Am I looking at a serious triple leaf headache here, or are the different spacings, plus the rather wide 18" spacing between leaves 2 & 3, going to perhaps cut down on or eliminate the "triple leaf effect"? Perhaps it will cause trouble only at very low frequencies? If so, any prediction on what frequency area might be a problem? Finally, with "triple leaves", there must come a point where the negative effect of triple leaf drops to the point of not being a problem once you reach certain leaf spacings. To exaggerate my point, if leaf one was 12" from leaf 2, and leaf 2 was 15 feet away from leaf three, is this even still considered triple leaf??? Or is it considered double leaf that is 15' from another separate wall??? You see my point. So... at what distances of 3 leaves nullifies the triple leaf effect? If my situation still seems bad, perhaps if I increase the distance of leaf 2 and leaf 3 from 18" to 24" I'll be ok??? Or 36"? Or 48"? Or 8 feet? I'd rather not get into more details of the situation I am facing right now since there are still too many variables at this point... may not even happen... but I'd like to discuss the triple leaf spacing issue anyway... I've always wondered about it.

29th March 2008, 04:00 PM	#2
gullfo Gear Head Join Date: Sep 2007 Location: Old Tappan, NJ USA Posts: 71	depends. in a voice-over studio on a 40 acre farm, its probably less of an issue than recording death metal bands in a room 2' from an ICU. 3rd leaf is generally bad, but not necessarily as bad as other choices. whichever is the least worst choice, pick that one, and live with the other. __________________ Glenn www.runnel.com

31st March 2008, 08:34 PM	#3
bpape Gear addict Join Date: Jul 2005 Location: St. Louis(Wildwood), MO Posts: 429	The difference in your scenario and the one (extreme) that you postulated is that in the 2nd one, there would still only be 2 leaves between rooms. In your case, there will be 3. There will be a frequency where it becomes an issue. at 12" it'll be relatively low but still may be a problem depending on your situation. Bryan __________________ I am serious, and don't call me Shirley Bryan Pape Lead Acoustical Designer GIK Acoustics

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2nd April 2008, 09:01 PM	#4
avare Lives for gear Join Date: May 2004 Location: Hamilton, On Canada Posts: 697	The frequency of the space is based upon the square root of the mass of walls and the space in between. The isolation of walls is based upon the the depth and mass. You put a leaf in between and you making two smaller mass-air-mass systems inter-connected and raising the frequency of resonance by half an octave. With the system you are talking about, the single resonance of the greater distance will be two thirds of an octave below the smaller space. Not insignificant. It usually is considered insignificant with quadruple leaf systems between across the corridor hotel rooms. More specifics are needed to give you good advice for you application. How thick are the current walls? How much are willing to spend to add mass? These are just starters. Andre