Room Acoustics

DEar MES

What is your wall made out of. If it drywall on stud it usually acts like a drum near the frequency you are describing.
If you do have that kind of drywall simply thump the wall in various areas and listen to the thud. Compare it to the pitch of the blooming artifact from the speakers. That might be helpful.
This is similar to the floor artifact you are describing bu thas a pitch nearer to what you are describing

jd

With the Eidolons, you may want to move them slightly away from or closer to the wall. This shouldn't substitute for troubleshooting the source of the noise. I have a pair of Avalons, and they are very picky of room position. I had a similar phenomenon, and I found that some loose flooring / rafter bracing in my house was the cause. There was a weekend when we were replacing carpet that I went around my living room, sinking a 5lb box of decking screws every 3 in in the subfloor; Went down stairs while the wife was jumping on the floor and marked all of the locations where I heard noise, and secured all of the bracing with glue and screws. I put R25 insulation in the floor joists with 5/8 drywall below the listening room. All of this including the carpet cost less than my interconnects, and made the whole room much more quiet. After I was done, I heard more noise, which turned out to be a bush on aluminum siding, rattling soffet, and some tin lamps on the wall. I would guess that the addition of granite slabs under the speaker will not fix your problem, but it is not a bad thing to try... Good luck!!

J K
I have a very funny graphic idea of that day in your house with your wife jumping up and down and you drilling screws into nearly annything that moved o rmade noise....sort of right out of bugs bunny or something
jd

$4700 retail in ASC traps and still a bass problem? Is there something wrong with that picture?

....some good suggestions though from those up above...good luck.

JDWEK -- It was kind of a funny scene... I am also a fan of Bugs and it could have been good 'toon material. I also caught the business from more than one that saw a screw every 3 inches... My floor doesn't make any noise any more...

Mes -- One thing I forgot -- are these Eidolons new, or not played often, or have been disconnected, moved, ect?? If so, let them break in for 500 hours and not worry about it(unless the bass sounds distorted or is breaking up). Avalons are by far the worst speaker to break in, requiring a lot of power and time. They will also get "cold" if not played at least once a week for a good listening session.