buying sound proof glass

surge · Post by **surge** » Tue Jul 27, 2004 4:00 am

Good Day,

I am almost finished in building my studio. I need now some sound proof glass. I was told that laminated safety glass would be the best. But I am having a hard time finding a store that has this. I live in NY, around long island, 30 minutes away from NYC. Anyone know of any places?

Also, how does my glass have to be cut? they say use 1/3 of the thickness of the wall for the glass, but does the glass have to be cut at an angle? Should it be thicker at the bottom and more thin at the top? Thanks

knightfly · Post by **knightfly** » Tue Jul 27, 2004 4:33 am

I'm not sure on sourcing, I"m on the west coast - maybe others closer can help, have you checked the yellow pages under glass suppliers? Here's the only result I got from US West's online when searching for "window glass laminated" -

http://www.dexonline.com/servlet/Action ... rom=&query Text=window+glass+laminated&cityText=&state=NY&Search.x=27&Search.y=9

Also, the laminated glass will give several dB better isolation than plate glass and laminated is also safer if it's broken.

If you mean the actual thickness of the glass pieces themselves, I don't know of any glass that's even available that is not a constant thickness. If you mean tilting one or both panes of glass in a window, this is mainly done to minimise light reflections which can cause visibility problems between rooms, and to redirect sound reflections away from the mix area. Unless you have really thick walls, though, you'll get better sound isolation with a wider gap between panes.

Hope that helped... Steve

surge · Post by **surge** » Tue Jul 27, 2004 6:02 am

Hello and thank you for your reply.

I was under the impression from speaking with a tech at sam ash, that the glass should not be the same thickness. The guy at sam ash said that one glass should face stright up, while the other one shall be tilted and one glass should not be as thick as the other. This was to reduce some kind of sound reflections or frequency.

What is the proper way to cut and install this glass?

Innovations · Post by **Innovations** » Tue Jul 27, 2004 7:21 am

surge wrote:Hello and thank you for your reply.

I was under the impression from speaking with a tech at sam ash, that the glass should not be the same thickness. The guy at sam ash said that one glass should face stright up, while the other one shall be tilted and one glass should not be as thick as the other. This was to reduce some kind of sound reflections or frequency.

What is the proper way to cut and install this glass?

Correct, the glass should not be exactly the same thickness and the sheets should not be parallel, but it does not necessarily have to be the vertical direction that they are tilted in.

Two other considerations as to deciding how you are tilting your glass.

Try to avoid tilts that would have light reflecting from the room lights into the eyse of the musicians or control room.

Try to avoid tilts that would reflect the sound from the musicians back into the microphone. Scale diagrams will help, Just remembet that the angle of incidence equals the angle of reflection both for light and sound.

Try to mount the two panes of glass in separate frames with some sort of a caulked or covered gap so that the frame itself does not become a path for sound to travel.

You can read more elsewhere on this site.

Post by **Aaronw** » Tue Jul 27, 2004 7:30 am

Cutting glass...not to difficult for standard glass. I'm not sure how they cut laminated glass (if they do).

DO NOT attempt to cut tempered glass. It will shatter/crumble. The only way for tempered glass to be resized is to have it reheated to the point of melting.

Aaron

knightfly · Post by **knightfly** » Tue Jul 27, 2004 8:33 am

Sorry, your question was worded in such a way that I thought you were asking if one piece of glass should be a different thickness at the top than at the bottom - but Aaron covered pretty much everything, so no problem... Steve

surge · Post by **surge** » Wed Jul 28, 2004 12:37 am

Aaronw wrote:Cutting glass...not to difficult for standard glass. I'm not sure how they cut laminated glass (if they do).

DO NOT attempt to cut tempered glass. It will shatter/crumble. The only way for tempered glass to be resized is to have it reheated to the point of melting.

Aaron

If I cant cut laminated safty glass, how shall I make them diffrent thickness?? It seems like cutting the glass might cost more money then the glass itself.. I am kind of wishing I didnt leave a big hole for the window. What other solutions are there out there?

knightfly · Post by **knightfly** » Wed Jul 28, 2004 1:09 am

I think there is some sort of communication problem here - I'll try another approach -

When you buy glass, you buy specific thickness - no one ever cuts glass to make it thinner, only to make it a smaller window size or to fit a particular frame. If you want two different thicknesses of glass in a studio window (and you do, if you need best isolation) then you BUY the glass that way - for example, you might buy one piece of glass that is 3/8" thick and 3 feet by 5 feet, and a second piece of glass that is 1/2" thick and 3 feet by 5 feet - the thinner glass would match the mass of two layers of 5/8" gypsum wallboard, and so should be installed in a wall built like that - the thicker, 1/2" piece, would match the mass of 3 layers of 1/2" gypsum wallboard and should go in the other wall frame (of a double framed wall) so that the mass of each wall leaf stays balanced.

At the same time, you do NOT want both leaves of a wall to have the same mass, because that means they will also have the same resonant frequency; this will make the wall weakest at that frequency. By doing each side of the wall differently, you change the resonant frequency of one half of the wall so that no single frequency finds an easy path through BOTH halves of the wall.

Safety glass, otherwise known as laminated glass, is made that way primarily for its safety factor - the viscous layer that is glued between panes of glass serves more than one purpose when that glass is used in a studio or other sound isolated environment -

One purpose is safety; when the glass is broken, the sticky layer between panes of glass keeps the pieces stuck together so you don't get dangerous shards of broken glass flying around loose.

The other purpose for acoustics is that this inner layer also makes the glass more damped, which improves its transmission loss.

Have I come any closer to answering your questions yet? If not, please say so; this is important... Steve

surge · Post by **surge** » Wed Jul 28, 2004 4:42 am

knightfly wrote:I think there is some sort of communication problem here - I'll try another approach -

When you buy glass, you buy specific thickness - no one ever cuts glass to make it thinner, only to make it a smaller window size or to fit a particular frame. If you want two different thicknesses of glass in a studio window (and you do, if you need best isolation) then you BUY the glass that way - for example, you might buy one piece of glass that is 3/8" thick and 3 feet by 5 feet, and a second piece of glass that is 1/2" thick and 3 feet by 5 feet - the thinner glass would match the mass of two layers of 5/8" gypsum wallboard, and so should be installed in a wall built like that - the thicker, 1/2" piece, would match the mass of 3 layers of 1/2" gypsum wallboard and should go in the other wall frame (of a double framed wall) so that the mass of each wall leaf stays balanced.

At the same time, you do NOT want both leaves of a wall to have the same mass, because that means they will also have the same resonant frequency; this will make the wall weakest at that frequency. By doing each side of the wall differently, you change the resonant frequency of one half of the wall so that no single frequency finds an easy path through BOTH halves of the wall.

Safety glass, otherwise known as laminated glass, is made that way primarily for its safety factor - the viscous layer that is glued between panes of glass serves more than one purpose when that glass is used in a studio or other sound isolated environment -

One purpose is safety; when the glass is broken, the sticky layer between panes of glass keeps the pieces stuck together so you don't get dangerous shards of broken glass flying around loose.

The other purpose for acoustics is that this inner layer also makes the glass more damped, which improves its transmission loss.

Have I come any closer to answering your questions yet? If not, please say so; this is important... Steve

here are the measurements for the window pane

20 3/4 inch in Height

20 3/4 inch in Length

3 1/2 in width (thickness)

According to these measurements, what should the thickness of my glass be?

knightfly · Post by **knightfly** » Wed Jul 28, 2004 9:45 am

I'll need more details before I can recommend anything - I need to know exactly how the rest of this wall is built, layer by layer, from the surface you see on one side step by step through the wall to the surface you see on the other side of the wall - if possible, a sketch or drawing would help too... Steve

Innovations · Post by **Innovations** » Thu Jul 29, 2004 12:09 am

Laminated glass, whether tempered or not, cannot be field cut.

Tempered glass, once tempered, cannot be cut by any means. You may some places see a cute decorative where they take a piece of laminated tempered glass and deliberately break it to get a fine webbing of glass granules in a flat sheet. Unfortunately you can't see through it worth squat.

Remember when measuring the glass to be exact, leave room for fiting and take into account the tilt!

surge · Post by **surge** » Wed Aug 04, 2004 12:25 am

knightfly wrote:I'll need more details before I can recommend anything - I need to know exactly how the rest of this wall is built, layer by layer, from the surface you see on one side step by step through the wall to the surface you see on the other side of the wall - if possible, a sketch or drawing would help too... Steve

well basically its just a room in a basement.

walls were made with gypsum, fiberglass acoustic insulation, sheetrock.

Its not perfect and we don't have the budget for that now. What we wanted was the mic room to be nice and sealed. It sits in a corner with half a wall of concrete and half wall we made. The wall is 3 and 1/2 inches thick and it has a square cut out, 20 3/4 inches in height and 20 3/4 inches in length. So we wanted to know how would be the best way to put this glass in and how thick should each piece of glass be.

We wanted the glass to fit right in the hole we cut. The only thing we are stuck on his how thick each piece should be and how to install and tilt.

knightfly · Post by **knightfly** » Fri Aug 06, 2004 1:40 am

With that small a window, I wouldn't tilt the glass at all - for best isolation, the glass should be as far apart as you can reasonably get it. You didn't say, but if the half of the wall you built is where the glass will go, and that wall is a normal stud wall, then you need glass for each side that is at least 1/3 as thick as the total drywall thickness for that side; if you have two layers of 5/8 drywall on the studs on one side, then the glass should be at least 1/3 that thickness, or 1/2" - if the other side is the same, then the same rule would apply - however, using different thicknesses for both walls and windows gives a bit better isolation at resonance frequencies so you could go with 3/8" glass on one side and 1/2" on the other.

Another advantage of NOT tilting the glass is that it's easier to measure correctly.

You seem to want details, but don't realize that you've still not given any - all you said was that "The wall is 3 and 1/2 inches thick and it has a square cut out, 20 3/4 inches in height and 20 3/4 inches in length" - is this a hole that's cut in the concrete part, or is this a standard stud wall using 3-1/2" studs and then drywall on both sides of these studs?

These are the details I was talking about... Steve