Control Room Window- 2 double panes?

[MikeB]

Sorry if this has been covered. I searched and could not find anything on it (granted, my searching skills are not all that)

In building studio control room windows, is it acceptable to use 2- double pane argon filled glass panes? just as you would use laminated glass normally (two of them angled down for light reflection).... so, a double pane insulated window- air space- and another double pane insulated window.... ?

I hope that explains it well....

Thanks in advance

[Soundman2020]

Hi there Mike B, and Welcome!

is it acceptable to use 2- double pane argon filled glass panes? just as you would use laminated glass normally (two of them angled down for light reflection).... so, a double pane insulated window- air space- and another double pane insulated window.... ?

Not really, since that creates a four-leaf system, and a four-leaf system implies worse isolation for low frequencies than the equivalent two-leaf system, all other factors being equal.

Double-glazed units, such as the ones you mention, have two thin panes of glass separated by a thin gap filled with air or some type of gas. That works well to isolate mid and high frequencies, but not so well for low frequencies, due to the problem of MSM resonance. When you have two such systems next to each other, things get worse, not better.

The only time this would work is if you had a sufficiently large gap between the double-glazed units, provided that each of them also had sufficiently high mass. The gap would have to be pretty big...

It is much better (and probably no more expensive) to just get thick laminated glass for each window, instead. The thickness is determined by the surface mass of the rest of the wall.

angled down for light reflection

Angling your glass also reduces isolation, since it reduces the size of the air gap along one edge of the window, this raising the MSM resonant frequency, which once again reduces low frequency isolation. If you want to angle your glass to reduce glare, then the gap at the closest point between the two panes must be large enough that the MSM frequency is low enough to isolate well at the lowest frequency that you are concerned about. If the wall design prevents you from doing that, then your only other choice is to use thicker glass (more mass) such that the MSM frequency is low enough.

A lot depends on doing the math and confirming that you have enough mass and a large enough gap to provide the isolation that you need, at the frequencies where you need it.


- Stuart -

[ABitAnalog]

It is much better (and probably no more expensive) to just get thick laminated glass for each window, instead. The thickness is determined by the surface mass of the rest of the wall

- Stuart -

Ok. Here is a question. I understand the thick laminated glass part. What is meant by the thickness is determined by the surface mass of the rest of the wall part? Does this mean that the glass should have the same (or greater) mass per sqft as the surrounding leaf of the wall? This makes sense to prevent the window from being an area of weakness in the wall for isolation.

Should it be thicker since there is no insulation in this area?

Is it important/does it matter that glass flexes differently than wallboard?

Thanks.

[MikeB]

Thanks for the reply Soundman, I suspected as much but just wanted to confirm. I have the insulated panels for free, so I was going out on a limb hoping that argon acted somewhat like a vacuum..... which got me thinking, "why not a vacuum between two panes?".... in simple theoretics it should prove nearly sound proof (sound, not traveling through a vacuum... only transferring along the physical connection of the panes).... Which got me thinking, "Why not make all your walls out of vacuum double panes?"... which got me thinking, "why not vacuum wall panels?"... which got me thinking, "how about a vacuum room not unlike the oldschool glass thromos bottles?"

I have a drum room, so the real lows will be better isolated than the guitars just outside the control room... I will see how one set of double pane works, but I'm guessing I will have to build proper windows.... after checking, first hand, on the advantage of slanted glass in regards to light reflection by tipping the glass and comparing, I will be going with straight and utilizing the

If you find yourself with some extra time go over any of that, I'd love to hear what you have to say (if it should be a new thread, let me know, I'll make one when I get back on)... .... I've been trolling for information on here for a while during my basement studio build... great wealth of information

[Oberon]

Mike,

Great concept idea on vacuum between lites for blocking sound, only it isn't really practical, unfortunately.

The window industry would love to be able to use vacuum glazing in their IG units for both energy and sound performance, but once you pull all the air out from between a couple of sheets of flat glass they collapse together and you end up with thermal and acoustic short circuit (if not broken glass) where the panes touch. Glass isn't rigid enough to maintain the gap in a vacuum.

There are a few folks producing vacuum glazing (mostly in Japan), but they actually put tiny plastic pillars between the glass panes to mechanically hold them apart in the vacuum. There is a small effect on thermal performance due to the pillars, but I have never seen any information on acoustic performance so I am not sure how much they affect sound transmission.

And, oh yeah, they are scary expensive.

Oberon

[Soundman2020]

Does this mean that the glass should have the same (or greater) mass per sqft as the surrounding leaf of the wall?

Correct! The density of glass is very roughly three times greater than the density of drywall, so if for example you were using two layers of 15mm drywall for your leaf (total 30mm), you'd need laminate glass at least 10mm thick (5+5 + PVB interlayer). However, you should always go a bit higher, since windows are always weak points, and you have no insulation in there, like you do in the rest of the wall. so I would go for 6+6 + acoustic PVB in that case.

This makes sense to prevent the window from being an area of weakness in the wall for isolation.

Yep!

Should it be thicker since there is no insulation in this area?

Yep! Plus the coincidence dip for the glass might be at a less favorable frequency than for the wall itself. Insulation slows down sound, so it makes the distance across the gap seem larger. Without insulation the gap seems like it really is, so it's also a good idea to have a larger gap between the glass panes than between the leaves, to compensate. And it's also good to leave plenty of insulation exposed around the edges of the gap.

Is it important/does it matter that glass flexes differently than wallboard?

Only for the coincidence dip. And that is usually high enough up the spectrum so as to not be too much of an issue.

which got me thinking, "why not vacuum wall panels?"...

You mean like Alien? "In Mike's studio, nobody can hear you scream..."!

I will see how one set of double pane works, but I'm guessing I will have to build proper windows....

You MIGHT be able to get away with one of those in one door, and thick laminate in the other. You can do the math for 3-leaf systems and see how thick the glass would have to be to make that work.

if it should be a new thread, let me know, I'll make one when I get back on

No, it's fine. Just carry on here.


- Stuart -