Rooms with concrete walls suffer from very strong room modes because the walls are rigid and there is almost no damping. They can also be very reflective at middle and high frequencies. For that reason, when people install sound systems in basements where all sides are concrete, it is best to install acoustic wedges or other absorbent treatments and panel dampers on the walls to damp room modes. Multiple subs are always a good idea too.
. . .when people install sound systems in basements where all sides are concrete, it is best to install acoustic wedges or other absorbent treatments and panel dampers on the walls to damp room modes. Multiple subs are always a good idea too.
Is that meant to contain echoes, to keep the sound from getting distorted, or to keep the sound from leaking upstairs? Do you think it's worse when the flooring is concrete too? I have a system in the basement and it's hard to hear it. But then again, it isn't an expensive setup. Just old gear.
Concrete surfaces on all six sides (4 walls, floor and ceiling) are problematic because there is so little damping. Reflections are strong and room modes are terrible. Even if you tame the high-frequency reflections with absorbent materials, room modes are still strong. Panel absorbers on all walls are generally the only way to cure them.
I've been having similar problems, rarerat. I tried to fix it the way you did, but I think I must have gotten some low-quality panels. My dad gave them to me, so I didn't really research them as well as I should have. What kind of foam panels did you use?
I bought some foam acoustic tiles for soundproofing from Amazon. They come in packs of 12 and measure 2 X 12 X 12 inches. They got a lot of good reviews which is what decided me as I have no idea what "Overall Noise Reduction Coefficient (NRC): 0.67" means - but that is what they offer.