Gearslutz.com - View Single Post - FRK facing used on the rear of fiberglass bass traps

Gohanto · 19th June 2009

I've seen the advice mentioned numerous times about having FRK facing only to the outside of fiberglass bass traps and removing it from the layers closer to the wall. I understand the definite advantages here with the high frequencies being bounced back into the room, but I haven't been able to find an explanation for why to not keep it on the back?

From my understanding, the air gap is present in porous bass traps because they work on sound wave velocity, which is 0 at the wall surface and higher further away from the wall. Then helmholtz and membrane traps work best near a wall since they rely on sound pressure instead of velocity, which is highest directly at the surface of the wall.

So, if the FRK facing acts as a limp mass membrane, then why would having that closer to the wall not help absorb more bass?

Thanks.

19th June 2009	#1
Gohanto Gear nut Joined: Mar 2009 Location: Honolulu, Hawaii Posts: 97 Thread Starter	FRK facing used on the rear of fiberglass bass traps I've seen the advice mentioned numerous times about having FRK facing only to the outside of fiberglass bass traps and removing it from the layers closer to the wall. I understand the definite advantages here with the high frequencies being bounced back into the room, but I haven't been able to find an explanation for why to not keep it on the back? From my understanding, the air gap is present in porous bass traps because they work on sound wave velocity, which is 0 at the wall surface and higher further away from the wall. Then helmholtz and membrane traps work best near a wall since they rely on sound pressure instead of velocity, which is highest directly at the surface of the wall. So, if the FRK facing acts as a limp mass membrane, then why would having that closer to the wall not help absorb more bass? Thanks.