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New HT Room Accoustiics


Active Member
A good friend of mine has just built some walls in his basement. He now has a room 21ft long 13feet wide and 7.5 feet high. He has a riser in the back 9 inches high for tiered seating. Am I right in saying that by filling the riser with fibreglass insulation that he would have a bass trap?

As well, he hasn't put the floor in yet and he had said he was going to carpet the whole area. But, I seem to remember that for the best accoustics the first 1/3 of the floor (at the front with the speakers) should be laminate/hardwood.
Riser with fiberglass.......I would look into other areas of the room to treat for bass (all corners).

Floor...if hardwoods can be tolerated in a basement, that would be best with some type of absorption between the main speakers (rug) for floor bounce. Personally, I'd use carpet for the comfort factor in a basement (cold floors).
I seem to remember something about having the mains sitting on a hard surface and having the first area of flooring being more reflective of sound. I also recall some pictures of engineered listening rooms, recording studio's and/or mixing rooms that had the front 1/3 of the room hard wood and the rest carpet.
yes, in practice a wood floor is best, assuming the walls are treated to absorb first reflections and the rest of the room treated to diffuse sound.

If I was working from scratch, I would put wood floors in and treat the walls properly. Then, if the room was still too live (bright and reflective), I would add throw rugs to the wood floor until the sound was tame. Putting carpet down forces a dead floor which cannot be undone if it is too much.

A room needs balance, and the side walls and front wall need treated for the best sound. If you treat the side, front, and rear walls to the extent necessary to get the most impressive soundstage, then the floor might need to be reflective to balance the overall room decay.
Flint, from reading your pinned thread, I assume the wood floor for the first reflection is better because it doesn't create the comb filtering that the carpet does? So the reflections get to your ears within a closer time period.

I really need to read the book that you recommended to me that I bought 2-3 years ago :doh: Master Handbook of Accoustics, if I recall.
FredtheFilmFan said:
Oh yeah, what about filling the wood riser with insulation to make a bass trap? Does that work?

Yes... Assuming the riser has large openings for sound to pass into the fiberglass.