AC Return for studio

[plurgid]

Guys:

I'm building my dream home studio in my attic. It's actually pretty cool, because the door to the attic is in the rear of a closet. Meaning there's like a little "air-lock" going into what will become my studio ... it's actually one of the reasons I chose this house when we bought it. With any luck I'll be able to bang drums in there at all hours without waking the neighbors.

In any case, there's no AC in there. So I ran some taps from from the main AC line, and that takes care of the input. But now I need a return. But the minute I put in the return ... there goes all my sound isolation.

How does one construct a sound baffling AC return?
Anyone deal with this before?

[nortstudio]

Typically ducting will be run, for as long of a distance as possible, preferably with some turns in the duct.

In the first studio I ever worked at, they had the AC duct running from the street all the way through the lobby (probably 30 feet) before it hit the control room. We never heard the AC noise, or any other noise from the ducts, because of the distance it traveled.

At my studio now, we decided on the Split Ductless systems (which would require a purchase - so may be out for you), and that has worked great - without causing major breach in the sound isolation.