John Sayers' Recording Studio Design Forum Archive

I’m building and installing the bass traps for my room and I was hoping to get a consensus on adding thin kraft paper to the front of bass traps (OC703) to improve low frequency response.

I have conflicting recommendations from 2 reputable sources: One states I should for all bass traps that are not in a direct reflection location, the other states I shouldn’t use kraft paper in order to get the best broadband absorption. I think they are both correct but which philosophy might be better for my 12’x19’ room?

Anyone have any actual experience to help me determine which route to go?

Kraft paper will not improve LF since it has no mass to speak of, if anything it will reflect high frequency back into the room. And unless you have a sure fire type glue to stick the paper to the insulation, it can and will rattle(vibrate) and this is the main thing we all fight against.

So if you require a lift in high frequency you could add the paper, otherwise, it doesn't improve the ability of the 703 to absorb low frequency...at all

I've read some advice from a very reputable source stating that you can attach the paper using a spray adhesive and that doing so would act as a membrane, like you stated. He also stated it would allow more of the high frequencies to remain and keep the room alive.

I am paraphrasing of course. I must admit I'm torn between doing this and not.

Warrior wrote:I've read some advice from a very reputable source stating that you can attach the paper using a spray adhesive and that doing so would act as a membrane, like you stated. He also stated it would allow more of the high frequencies to remain and keep the room alive.

I am paraphrasing of course. I must admit I'm torn between doing this and not.

I'm not sure you wanna call it a membrane. For a membrane to function it needs to be decoupled from the wool. That way it can vibrate on it's own in full effect. Without the wool suppressing the vibrations.

Adding any mass (be it paper, plastic or whatever) will act as a lowpass filter. Sure, paper has little mass so you can't really call it LOW pass But it'll filter some of the very high frequencies, sure.

I usually add a sheet of plastic in front of the wool to prevent high frq absorption. Since high frq will be easy absorbed by other stuff in the room you wanna "balance" your absorbers. Making a corner absorber doin' only low/mid end is a good start.