constructing baffles?

T

troutmask

New member
Hello,

I'm currently part of a recording project that is attempting to set up a make-shift studio in a basement. Our main priority is that, since we're going to be recording live, we want to cut down on as much excess noise from instruments as possible (we'll also be treating the HVAC system, since it starts rattling whenever bass frequencies enter the picture...it has no effect on our sound, but drives people who are upstairs nuts). I know that soundproofing the basement and isolating each instrument isn't an option here, so what I'd like to do is construct some home-made baffles (well, I'd like to think of them being constructed more like shields) to at least help in this matter. Does anybody have any advice here? We were planning on constructing them out of plywood and covering one side with dense foam (I work at an upholstery shop by day, and I have been granted free reign over the scrap foam). Has anyone ever tried anything like this before? If so, should we put foam on both sides instead of just one? Will the thickness of the foam (as well as its density) make a difference here? Any help would be greatly appreciated.
 
Trout,

> We were planning on constructing them out of plywood and covering one side with dense foam <

Even better than plywood is MDF, though plywood is okay too. Use two thicknesses of 3/4 inch plywood or MDF to extend the isolation to lower frequencies. Of course, a lot of sound will still go over and around the baffles.

Upholstery foam is not the same as acoustic foam. Even acoustic foam is not that good unless it's very thick. Much better is rigid fiberglass, though it's harder to find and you have to cover it with fabric for appearance. If you decide to use foam, get acoustic foam. Upholstery foam just doesn't work well for this.

--Ethan
 
so, I assume that even thick upholstery foam won't do much good in this regard...well, how thick should the acoustic foam be on the baffles? Is there any good resource for buying acoustic foam online?
 
Trout,

> so, I assume that even thick upholstery foam won't do much good in this regard <

Exactly.

> how thick should the acoustic foam be on the baffles? <

Two inches is okay, four is even better.

> Is there any good resource for buying acoustic foam online? <

I'm not a fan of foam becase rigid fiberglass is so much better. But if that's what you can afford search for Foam By Mail.

--Ethan
 
Thanks for your help so far...just one more thing (well, two, but)...

So, if the baffles are built using two sheets of 3/4", and I used foam, would I also put foam in between each sheet of wood, or would it suffice on just the outside? As for the rigid fiberglass, if I were able to find it and use it (as well as afford it), how thick should it be?
 
Trout,

> would I also put foam in between each sheet of wood <

No.

> would it suffice on just the outside? <

Yes, and putting absorption on only one side is pretty common.

> As for the rigid fiberglass, if I were able to find it and use it (as well as afford it), how thick should it be? <

Look in the Yellow Pages under Insulation and also Heating & Air Conditioning. You want at it to be least 1 inch thick, and 2 inches is even better.

--Ethan
 
isnt it bad to breathe that stuff??? i thought you were supposed to use it in your walls or in the attic only

T
 
That's why you wrap in fabric. However, you have to find a thin and porus enough fabric to allow the higher frequencies to pass through it and enter the fiberglass, otherwise the high frequencies will just bounce right off like they would with drywall. But the fabric also has to be thick enough to keep the fibers in. A good way to test it is hold it up and try to blow through it. If you can feel it on the other side, it will be thin enough for those higher frequencies.
You'll also need to construct something to hold the fiberglass up. Some people use a plywood backing. I use frame's made from 2x3's.
 
I think you are talking about duct board. It is usually about 3/4 inch thick with foil on the back side?

That stuff is the best for sound proofing. Put in the wood frame cover with fabric that looks nice and your done.

Foam is not good for sound proofing it is only good at "shaping" the sound of a room but provides very very little when it comes to sound proofing.
 
I just scored some late 1970's office cubicle dividers; they're solid wood with some sort of padded and cloth covered faces. Feels like stiff fiberglass, you can dent it with your fingers if you push hard enough.

Best part: Free.

Should help me quite a bit with room rumble in my 14X28 room with 12 ft ceilings and hard plaster walls with tile floors.

Ask contractors and construction guys, they seem to be good resources for stuff like this; lots of times when they refurb and office, people just throw the old stuff out.

Chris
 
We built a few as follows; cut a sheet of 3/4 plywood in half so you have two pieces 4 feet square, build a frame out of 2X4s including a center brace, glue or caulk the frame and attach 3 sides and the center brace to the plywood, fill the space with sand, attach the final piece of frame, (be sure to use plenty of screws) cover the whole thing with carpet. These things work great but they are quite heavy so if you expect to have to move them around much you might discover (as we did) to put wheels and handles on these things.
 
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