Originally Posted by 4kicknsnd
Sorry - calibrated using Audyssey on Denon receiver - sub is set at 0 in AVR. Sub is in line with front speakers - tv. Right now it is between the TV and the right tower. Even tried swapping places with right tower just to see if that would make a difference and it sounded pretty much the same to me. The only other suitable location is on the back wall directly behind the MLP. Just seems to be with any material that is more middle ground on the frequency chart. Not just the guitar I mentioned either - there is other music played - what I call mood music - and that also has that same effect. I guess it is more noticeable in that game because the sound effects are drawn out more than just a quick note.
What you are describing sounds to me like a room resonance occurring at a particular frequency. I had something like that with a large speaker which was somewhat corner loaded with a built-in cabinet. I got a really gnarly sounding resonance, from the cabinet itself, at around 60 or 70Hz. My only recourse in that case, even with XT-32, was to either move the speaker, which I couldn't do, or to add a corner bass trap there, which worked just fine.
I have no idea why your Cap 1400 would excite a room resonance (not room mode--this where some wall or object in the room resonates sympathetically at a particular frequency) where your PB13 did not. Did you try the back wall, just to be thorough? When you said that you switched positions on the front wall, at first I thought that it couldn't be something in the room resonating, but perhaps it could be that whole front wall. Try pulling the sub away from the wall by several inches. It doesn't sound as if you need the boundary gain, and if it is the wall resonating, that might help.
The only other explanation I can think of seems far-fetched, and that would involve an issue with the cabinet of the Cap 1400 itself. It does sound as if what you are describing is a sympathetic resonance, and I suppose it is conceivable that there there could be some flaw in the cabinet that could cause that. Frankly, I doubt it, but if you try moving the sub out more from the wall, or in other room locations, I don't know what else could be responsible. Try moving the sub and then let us know.