Airconditioning in the studio

[skunkyfunk]

One major problem in recording studio design is how to make everything airtight.  Hence, should you really wanna make your studio soundproof, you obviously need proper ventilation as well.  Wait a minute - AIRTIGHT and VENTILATION don't really go hand in hand.

So what I did with my project studio was use a split type AC for the instrument room, and while using a duct and an exhaust fan seemed economical, I was discouraged because the isolation between the control and instrument rooms shall diminish largely.  Hence, I installed a window type AC in the control room (0.6 horsepower - very small) but I have a few gripes. 

1)  The window-type AC in the control room has quite a high noise floor in comparison to the split type AC in the instrument room (almost inaudible)
2)  A lot of leakage is going out of the window type AC despite the double doors and the isolation materials. 

Is there a way to fix the sound leaks in the window type AC?  Would it be nice to make some sort of canopy around the AC's housing outside and put some fiberglass with foil?  But of course I need to have room for exhaust as well.  How's that?

[mikep]

I have always ducted the air con of the studios I've designed and built, even if they are split types.  Noise floor is normally very low - NC 25 at least.  Definitely, it would be hard to use window type air con for recording studios, but if you must, the best you can do is just to quiet it a bit.  Make a shroud, like a duct for both the supply and the return of the aircon.  This has to be separate otherwise you will be short circuiting the inflow and outflow of air - hindi lalamig ang aircon.  Make your duct in an S type configuration, going up the ceiling.  Put 1" thick glass fiber inside the duct - both of them.  Cover the insulation with acoustically transparent cloth like thin katsa. It will not look at all pretty because it will be sticking out into your room, but you will sort of make the noise lower than what it is now.  The S and the bend is important as you would want the air to hit the bends to lower down the noise (absorbed by the 1" glass fiber) before it goes out into the room.  Another thing is, make sure the ducts are oversized so that the air flow would be slower and diffused.  This is a temporary solution to the problem.  Furthermore, how about the vibration of the window type aircon that is transmitted through the walls?  Laki na naman problema.

The better way of doing it is using split type air con system and putting ducting as well.  I find the split type air con still noisy.  And the mics, especially condensers, pick them up.  Sayang lang soundproofing mo!

FWIW

[KitC]

The alternative would be to cool the room first, then turn off the aircon while tracking, then turn it back on during breaks.

Mike, since I'm a Mech Engr., I'm curious how you design your ducting. There's only so much soundproofing and baffling that you can put in ducts before it becomes inefficient (air friction becomes a BIG factor).

[mikep]

KitC, there are several ways of doing it.  First, you make sure that the airflow is slow, preferably about 350 ft. per minute - no more than 500 ft. per minute, so oversize the duct.  Second, put insulation in the inside of the ducting to reduce resonance and help in reducing air noise and hiss.  Third, use bends to dampen the air flow a bit more.  Finally, use plenums to further help in reducing the noise.  So, there.  I normally achieve an NC 20 in most of my projects.  I never really encounter much air friction with this method.

FWIW

[TheHunter]

The alternative would be to cool the room first, then turn off the aircon while tracking, then turn it back on during breaks.

I been playing around with my a/c to lower down the noise but I ended up of turning off while tracking.

[marvinq]

The alternative would be to cool the room first, then turn off the aircon while tracking, then turn it back on during breaks.

hey kit, that's actually how i do it in my home studio.

now if only there was a way to get rid of that loud videoke (they only hit the right notes on SPECIAL OCCASIONS!) from the neighbors.

[KitC]

now if only there was a way to get rid of that loud videoke (they only hit the right notes on SPECIAL OCCASIONS!) from the neighbors.

Remember the Bose Quiet Comfort noise cancelling headphones? What if you point a PA in their direction and send back an out-of-phase signal in their direction?  Either that or create a small radius EMP grenade. 

[bangbus]

Either that or create a small radius EMP grenade. 

do teach teach teach! please, how can i make one of those?

[KitC]

Either that or create a small radius EMP grenade. 

do teach teach teach! please, how can i make one of those?

OT: I've been trying to formulate a tight focus EMP beam, but present technologies point in the direction of microwave emissions or a small yield nuclear blast.   

Back to topic.

[marvinq]

english please. hahaha.

[mikep]

No can do, Kit.  First, you have to make sure the sound is contained within the room (you might as well soundproof the room) to be able to control it.  Second, the noise coming in should be not an erratic or intermittent one.  It has to be predictable for the DSP controller to sample it.  Third, you would need a lot of mics, speakers, DSPs and computers to make this thing work.  In reality, this, in essence, is active noise cancellation.  Been done.  Being done in airplanes to put down engine noise in cabins.  Done in some auditoriums and acoustic spaces that need soundproofing but cannot do any physical touch ups because of historical importance (like castles, some churches, etc.). The process will be more expensive than soundproofing the room.  Unless you can come up with something else.  Then, you make money.

[KitC]

Unless you can come up with something else.  Then, you make money.

Hehe, I was thinking out loud, Mike. A sort of "what if?" scenario. I knew it would involve a lot of DSP and even  "look-ahead" algorithms. AFAIK, the best they could achieve is still a one cycle delay from the actual waveform (correct me if I'm wrong on that one). With all the reflections coming from the source, it really would be next to impossible, but hey... that's what they said about going to the moon once.

EMP grenade? Now there's an idea! I suddenly remembered those "Domes of Silence" from the ol' Get Smart series. Hilarious! 

[starfugger]

this stuff is harcore.  haha.  doesn't that noise cancelling thing cause head aches?

[xjepoyx]

this stuff is harcore.  haha.  doesn't that noise cancelling thing cause head aches?

waaaaa... its really a major head ache.... lalo na when we first started to do home recording.

One major problem in recording studio design is how to make everything airtight.  Hence, should you really wanna make your studio soundproof, you obviously need proper ventilation as well.  Wait a minute - AIRTIGHT and VENTILATION don't really go hand in hand.

So what I did with my project studio was use a split type AC for the instrument room, and while using a duct and an exhaust fan seemed economical, I was discouraged because the isolation between the control and instrument rooms shall diminish largely.  Hence, I installed a window type AC in the control room (0.6 horsepower - very small) but I have a few gripes. 

1)  The window-type AC in the control room has quite a high noise floor in comparison to the split type AC in the instrument room (almost inaudible)
2)  A lot of leakage is going out of the window type AC despite the double doors and the isolation materials. 

Is there a way to fix the sound leaks in the window type AC?  Would it be nice to make some sort of canopy around the AC's housing outside and put some fiberglass with foil?  But of course I need to have room for exhaust as well.  How's that?

what we did before dun sa old house namin and we created our make shift vocal booth(3 square meters with egg trays all around the booth) is nag lagay kami ng 2 square holes (1ftx1ft) leading to a some sort of tunnel vent w/c is around 5 meters in length. sa dulo nung magkabilang tunnel we placed a small exhaust fan backward so the air will go inside the vocal booth.


sa ngayon di pa kami makagawa uli ng vocal booth kasi newly constructed pa lang house namin at malamang patayin ako ng misis ko hehhe

[skunkyfunk]

Furthermore, how about the vibration of the window type aircon that is transmitted through the walls?  Laki na naman problema.

FWIW

Sir Mike, I knew that the metal studs would be a problem for the AC.  Apparently, the wall where I installed the AC was half concrete (from the ground to a meter high) and the rest was plywood!  It turned out to be an expansion from the original floor plan and maybe the owner wanted to save money by not using a solid concrete wall.  Anyway, this was a bit of an advantage though, as I was able to use 2 layers of rockwool and 3 layers of gypsum board (Gypsum-rockwool-gypsum-rockwool-double gypsum) and I put some duct tape and rockwool around the hole for the A/C.  I encountered no problems so far with the AC's vibrations. The real problem is only with the AC causing leaks - but it turned out that turing on the AC voids the noise that can come put from the control room.  But then, it's the AC's noise that has to be dealt with.

But with all these Noise crtiteria levels, I wonder how much the PC fans, AVR's  contribute as well.  So are you saying a SPLIT TYPE AIRCON gives you something ABOVE NC 25? 

[mikep]

as I was able to use 2 layers of rockwool and 3 layers of gypsum board (Gypsum-rockwool-gypsum-rockwool-double gypsum) and I put some duct tape and rockwool around the hole for the A/C.  I encountered no problems so far with the AC's vibrations.

The better way of doing it is two gypsum-rock wool-2 or 4 inch air gap-rockwool, gypsum.  Duct tape around the AC hole is not enough to stop sound from seeping through.  You do not feel it, but there are vibrations which are coming out as if they are part of the noise of the aircon.  The hard part now is how to contain the noise of the aircon and making the intake and supply of the unit efficiently.

Depends on the split type model.  There are suoer quiet ones but are still picked up by condenser mics.  The way to do it if you do not duct the air con system is to position the mic so that its back (cardioid) is facing the air con.

FWIW

[TheHunter]

Well, we can minimize the A/C mechanical noise but is not easy to minimize the air noise coming from your A/C.