I used 1/2" plywood and some 2"x2" for the corner joining and basically built a box around my 80 gallon horizontal compressor. Made a huge difference-but the real noise was coming from the air intake. Made it tolerable and could at least talk without yelling. Figured I could line the "Box" with R-30 foil backed insulation if I got real serious-but been like that for over 20 years.:grinpimp:

 

pipe your air intake(s) outside

 

our compressor is in a un heated section of the attic. no issues in 10+yrs. it also gets cold in NY.
make a little shed on the outside of the shop that you can put more than just the air compressor in.

 

I am putting a pad on the back corner of the shop to house the compressor and air dryer... enclosed with vents, and enough storage room for misc things related (oil, parts, etc). I plan to insulate mine, and put up some type of sound-deadening material maybe even just foam to try to keep it quieter.

 

I just built a box for my oil less compressor(ie:LOUD), 4 sides, front top and sides, I lined the inside with r-19, and pushed it up against the wall over the comp. There is a 1-2 inch gap on the top too the wall letting air flow, If it doesn't flow enough i will add a fan...But as it stands now it cannot be heard from the street with the garage open. Cost 15 bucks for the r-19, and the 3/4 ply was in the back of the garage.

 

How about this then?

Enclosed box with insulation/sound dampening material. Run a 90degree vent tube out to keep the compressor cool, and a line for the intake to pull outside air?

Bad idea? Good idea?

 

Mine is on the second floor of the shop. It helps, but it is going outside soon. I was at a guy's shop last week adn I couldn't even ehar either of his two compressors that were running outside in a shed. He says he's had them out there for 18 years without a problem.