Sliding glass door resonance

watercourse · Post by **watercourse** » Tue Dec 06, 2005 1:32 pm

I recently completed construction on my recording studio, due in no small part to the generous wealth of information provided on this forum. Thank You!!!

I've come across an issue I'd like some advice on. I've incorporated a sliding glass door system to separate the main recording room and control room. The design is based on John's garage studio design with two sliding glass doors separated by an air gap and angled 6 degrees from each other. I'm getting some resonant ringing of the door glass during loud tracking, say with a heavy hitting drummer. It ranges from subtle to rather distracting.

Is there anything I can do to dampen the glass or to absorb the range of ringin? I love the visual openness of the sliding door design and would like to keep it untainted if possible. My current plan is to make removeable fixtures made from auralex wedgies (leftovers from a previous project, before I stopped using foam. I also have some mineral wool leftover). The fixtures, maybe 1'x2' in dimension, would press to the center of the door glass on each panel to damp the ringing. I'd just use them for loud, percussive sessions and remove them afterward to keep the clean visual appearance.

Would this help reduce the ringing and/or are there any other ideas I could try to help minimise the glass resonance? Thanks very much in advance.

JohnGardner · Post by **JohnGardner** » Wed Dec 07, 2005 5:52 am

Could you advise us what size the minimum airgap is between the two panes of glass (doors) and what thickness each pane (door) of glass is.
Thanks
JohnG

watercourse · Post by **watercourse** » Wed Dec 07, 2005 7:02 am

The minimum air gap between door panes is 7" and each pane is 3mm thick. I just discovered each door is double-paned, meaning 2x3mm of glass per door and also meaning I've constructed a lovely example of quad leaf design

I may do a redesign later to fix the inherent quad leaf problem, but for now I'd like to see if there's anything I can do to improve the situation as it is.

andy_eade · Post by **andy_eade** » Wed Dec 07, 2005 8:05 am

That raises an interesting question.

At what point is it okay to use said sliding glass doors with double-pane construction (I'm going to assume most are constructed like this).

i.e. in my design below I have a booth with a sliding glass door on each side, but it is quite small. At what point is the partition big enough that you have overcome the "quad leaf design" syndrome?

Apologies if this question has been answered elsewhere - feel free to re-direct me if this is the case.

Best Regards.

knightfly · Post by **knightfly** » Thu Dec 08, 2005 2:25 pm

Andy, the "quad leaf" syndrome will be there no matter what the dimensions - of course the larger the surfaces the more evident the resonance. If you put two 1/4" panes of glass 1/4" apart, the m-a-m resonance is around 275 hZ or so; this is really close to typical kick drum shell modal frequencies, and low toms could excite it also. Two such doors spaced 7" apart would have TWO double leaves with such resonances, PLUS the resonance of the 7" air gap ( around 52 hZ) PLUS the possibility that the 52 hZ resonance's 5th harmonic would sympathize with the higher one, plus.....

Using the foam or some other sort of damping material between doors should help some, not sure how much. This could also be caused by basic vibration of the entire door in its track... Steve

andy_eade · Post by **andy_eade** » Fri Dec 09, 2005 12:59 am

Would I be wise to look for single-pane sliding glass doors then? Do they make such a thing?

knightfly · Post by **knightfly** » Fri Dec 09, 2005 4:29 am

It's apparently getting very rare to find single pane sliders, as evidenced by a google search I did; only useful thing I found was this

http://www.jeld-wen.com/_pdf/resources/ ... JGI027.pdf

which has some interesting glass info but NOT useful for your question

I'm personally not a fan of sliding glass doors for studios (I prefer better isolation) so I've not kept up on this at all.

About the only way I know of that might work to get two single-panesliding doors would be to have them modified locally by a good glass shop; doubt if it would be very reasonably priced... Steve

cyeazel · Post by **cyeazel** » Fri Dec 09, 2005 8:05 am

Andy, in reguards to your question about the glass doors, I'm wondering if what you were meaning to ask was how big of an air gap (the width of the actual booth) will negate quadleaf effects. After re-reading your question, that is the impression that I got. If I am wrong, I apologize. Were you intending to ask about the amount of airspace between both door systems or the airspace between panes in the individual systems?

andy_eade · Post by **andy_eade** » Fri Dec 09, 2005 1:13 pm

cyeazel,

Yes you were right first time. I was wondering about the width of the booth and at what point that width negates the quad-leaf effect....

Thanks,

Andy[/quote]

cyeazel · Post by **cyeazel** » Fri Dec 09, 2005 2:07 pm

Thats what I thought but I wanted to make sure. So what you are actually wondering is if your booth is wide enough to compensate for your 2 quad leaf door systems. I don't know that one for sure. I'm not qualified to do the calculations, but others can.

knightfly · Post by **knightfly** » Sat Dec 10, 2005 6:22 am

Sorry; missed that. The answer is - I'm not sure exactly. From conversations with degreed acousticians I'd say somewhere around 10 feet between doors; and even then, the frequency of resonance between the two panes of each door would pass through the entire construction easier than non-resonant ones. The good news is, that's usually high enough that other construction would mask it; but that still leaves the crappy low end isolation caused by the 4 leaves... Steve

andy_eade · Post by **andy_eade** » Sat Dec 10, 2005 6:32 am

Do you think I should kill the idea of having the booth in the middle then?

Also, I noticed that most people here that have used sliding glass doors have used two together. I've read that some are working just fine. In my configuration I'm assuming that adding two more would not add anything but would just cost me more. Am I right in thinking that by having the booth it gives me better isolation between the Drum room and control room than by not.

Alternative would be to use my acoustic solutions window, add two solid core doors and not do the booth - just CR and Drum Room.

I keep looking at the plan though and I have to imagine John had a reason for doing this...

knightfly · Post by **knightfly** » Sun Dec 18, 2005 5:40 am

That plan works well ergonomically, which is probably a lot of why John proposed it; also, using single doors each side will give a double leaf between the LR and the CR, with a large air gap (the booth) - plus, generally, not as much isolation is needed between a booth and the CR as between a drum kit and the CR.

Looks like that's as good a design as any, overall... Steve

andy_eade · Post by **andy_eade** » Tue Dec 20, 2005 12:26 am

Yep - that's what I was thinking. Thanks for setting an incompetent mind at ease!

len-morgan · Post by **len-morgan** » Tue Dec 20, 2005 8:34 am

Have you determined if it's a resonance in the glass you're hearing or as Steve suggested, just the whole shabang vibrating in it's tracks? If it's in fact the glass, I would think you could get a couple of big pillows, tie a rope around one end and nail the other end of the rope just above the door so that the pillow is leaning against the glass. It might help to put a rock in with the pillow just for a little extra weight but please remember which side of the pillow the rock is on!!!

It could be a mess to clean up otherwise.

I don't suggest this as a permanant solution - just an experiment to find out the source of the noise.

len

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Sliding glass door resonance

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