Hard to tell without seeing the situation. Sounds like the doors themselves are rattling. Do whatever you can to tighten everything on them. Even take out the class and reseal it. Also, There is another thread with a question about sliding glass doors you might want to check out ({old-link-removed}). There, Keith gives a great link to the AES website that has a lot of good studio construction pointers that might give you some insight to your problem. One things it suggests is to not allow the glass pains to be parallel to each other. You may have to rip them out and put them back in to solve the problem (hope not!).

-Jon

Have you tried putting a muffler on the glass? Like a muffler on a kick drum?

I don't know? Double-sided tape with a piece of carpet/padding stuck to the door? A piece of plywood? May not need to be a big piece, just something to stop the resonance/vibrations... Maybe tape itself would be enough???

Don't "take apart" the sealed glass in a modern window/door(Unless you want to buy a new door shortly thereafter?)((Which, come to think of it, may be the best idea of all......))

TG

glass doors

If your resonance centers around 1500 hz its a standing wave between the glass walls. If its lower its the resonance of the glass panes themselves or standing waves they generate in the rooms they are facing.

The fiberglass might reduce the standing wave but denser fill material will be better - use 4" acoustic foam between them. If its the panes the bass drum damper type idea will work.

If you just can't fix it, and the problem is all over the spectrum, I'd suggest building large bass absorbers out of 4x8 x 1/4 plywood, and lean them at an angle over the doors. This is absorb the lows, and deflect the highs at oblique angles, and generally get the glass out of your sonic equation. Glass is a pain, generally.

How about the 4x8 panels of(House-covering, under the siding) very hard foam you can get at the Home Depot? Comes in thickness up to about 4", easily cut-shaped. It's covered with aluminum or plastic foil but, here that shouldn't matter. Stick a piece(Or two) of this between the doors? Again, if you're getting a resonance, all you have to do is "disturb" or "break" the resonance enough to do what you've got to do. If it works(Maybe just a small piece will do?) and it looks really stupid, you might cover the foam with fabric or peel off the aluminum and paint the stuff.

Maybe just peel it, paint it, put it on "legs"(Or props) and stand it in front of the door? If it works here, other pieces of the stuff might be good for other "sound things"?

Hmmm, what am I telling YOU this for? I could make a business out of this foam crap!

Studios "angle" large glass between rooms- Usually two or more "layers" just like your doors. Probably helps to disburse sound waves up or down instead of straight back and to also "disburse" light waves(Minimize reflections in the glass). I know this doesn't help here, but, point is large areas of glass(Large flat areas of anything!) WILL be a problem if not taken into account in the room design. Every pretty glass door and window in every "designer" room was carefully considered(And probably cost a mint!).

TG

The glass definitely needs to be angled...7 degrees, according to John Woram. Most certainly NOT "straight up". A "gobo" placed strategically in front of the glass may help diffuse the offending resonances. Teddy's idea seems pretty good. I haven't tried that particular material before, but have made a slew of goboes with MDF covered with rockwool. Those louvered folding closet doors you get from home centers can also work as the "foundation" for that. Anyway, you can get artsy-fartsy with it by covering them with upholstery fabrics, even remnants from home decorator shops.

The glass definitely needs to be angled...7 degrees, according to John Woram. Most certainly NOT "straight up". A "gobo" placed strategically in front of the glass may help diffuse the offending resonances. Teddy's idea seems pretty good. I haven't tried that particular material before, but have made a slew of goboes with MDF covered with rockwool. Those louvered folding closet doors you get from home centers can also work as the "foundation" for that. Anyway, you can get artsy-fartsy with it by covering them with upholstery fabrics, even remnants from home decorator shops.

Yes, that's the word I couldn't think of - "gobo". Anything absorbant or even properly reflective, put in front of the doors might help... They do make them, on stands to move around to suit... Shame though to go to the work and cost of putting in the door than to put some big, clunky thing in front of it... Oh well, live and learn.....

TG

I hate glass in a studio. I can see my reflection. And anything
that will bounce that horror back at me will certainly do the
same to the sound!

Don't use glass! Use a wood door with a tight latch. Maybe a 12"x12" window in the door at most. Caulk the sh!t of the glass to remove any vibration.

Communication between the sound engineer is all through the headphones anyways..

This also allows the artist/singer more privacy thus creativity...

I would think that glass doors would be avoided at all costs!!! Glass is very sound reflective!!!

my 0.02

-m

I agree with 6string. I don't even use a window between the rooms. I use headphones and a talkback mic. I use a heavy gauge insulated steel door. I don't like my door but I couldn't imagine using sliding glass doors, seems like a lot of reflective surface to deal with.