Control room window design

[RawDepth]

I am building a new wall to separate live room from control room in my home. I have been considering different types of window designs.

Today I found four large windows for sale dirt cheap. They are each fixed frame, double pane, and argon filled. So I did some research on the nature of argon gas windows. (BTW, much of the talk here is generally against the use of argon filled windows, though I don't understand why.)

Argon gas is selected for windows because the molecules are slower moving than those of air. Sound waves, just like heat energy, must excite molecules in order to disperse outward. It stands to reason that Argon will hinder the transfer of sound energy in much the same way that heavy mass does. Heavy mass resists movement and Argon gas resists movement.

If these windows were installed with at least 12" of air space in between, (double glazed gas pocket - air spring - double glazed gas pocket,) they would likely perform similar to thick single panes (mass) with the same air space.

Wouldn't you agree?

 

[Nitemare2970]

I would definitely think so. I mean if you have a 12" air pocket between them, it should be more than enough to stop most if not all transmission of sound waves. Thats just my 2 cents....

 

[RICK FITZPATRICK]

If these windows were installed with at least 12" of air space in between, (double glazed gas pocket - air spring - double glazed gas pocket,) they would likely perform similar to thick single panes (mass) with the same air space.

Wouldn't you agree?

No. If they did, Pro studios would use them first as heavy thick glass is expensive. Mass is the name of the game. From the "experts" mouth.(Eric Desart..acoustician who designed Galaxy studios)

It changes the TL curve gaining somewhat in mid and highs but makes the mass-spring more explicit. This means that it in fact for music it's worse.

http://www.johnlsayers.com/phpBB2/viewtopic.php?f=2&t=1820&p=13216&hilit=argon#p13216
fitZ

btw, there are litterally dozens of examples at Johns site why it doesn't improve TL or equal massive glass. Do a search on "argon" and you will see.

 

[RawDepth]

I browsed around over there for a while. It appears that most folks are perpetuating the idea that argon is worse, but none are offering any real explanation as to why.

I did some more digging on the Internet and came up with test results that deflate this somewhat.

http://www2.dupont.com/SafetyGlass/en_US/assets/pdfs/pvb_soundtransmission.pdf

Examine this chart for a while. Granted, their testing was mainly focused on DuPont Butacite, (which is a thermoplastic interlayer used in making laminated safety glass,) but it does show one interesting point.

Most of the line entries on this chart show the different thicknesses of the Butacite layer between the glass. (The dimensions shown in decimal form are the thickness of the Butacite product.) However, the last two lines are identical except for the 1/2" void. One is filled with air and the other has Argon. Some frequencies have better TL, some have worse. In fact, the TL gets better in the mid-range where our ears are more sensitive, this is a good thing.

It may be a wash in general. The differences in TL are small. Only one dB on most frequencies. So, the gas doesn't seem to be changing much if anything considering the full spectrum.

I admit the chart does prove my theory wrong. The numbers are not greater like thick glass would have given. However, the Argon numbers are not far worse either as they claim.

I don't dispute that thicker glass gives a greater TL. But I cannot afford thick glass for my home hobby cave. The windows I found are cheap (4 large fixed frames for $20 each) so I may just go with them and enjoy my little live room anyway. Hell, the large air space alone will probably give decent transmission loss.

I am following their advice on the wall construction tho. Thanks, man.

 

[RawDepth]

As a side bar...that Butacite stuff really improves TL performance. I wish we could compare single two ply safety glass (1/4" 0.060 1/4") to regular monolithic 1/2" glass.

 

[Treeline]

You may be onto something - while thick glass may be better, you have a budget and the major studios built as if they did not. Try it and see what happens.

One thing to be sure of, though, is to avoid parallel windows. The plane of the studio A window must not be parallel with the plane of the control room window. A typical way to install these is to engineer a 5% or so angle with the panes closer together at the bottom sill than at the top. You also want to be cognizant of the reflective characteristics of the window to the studio space, so an idea is to create a few degrees angle between the studio plane and the window surround.

The whole idea is to frustrate the production of standing waves and to avoid having the window severely affect the studio sound. Look at the pic to see what I'm talking about.