Bad move?

[Davemcc]

I moved my PB12-Plus from one front corner of my room to the other. I defeated the Parametric eq to take new readings with Avia for a new eq setup and I can barely comprehend what happened. I had 74dB @ 60Hz, then a steady climb to 102dB @ 40Hz! That's raw, uncorrected SPL which would look worse once corrected I'm certain. LFE pink noise was floating right around 85dB.

Is this crazy or normal?

 

[markw]

Congratulations!

You've just discovered resonant room nodes!

http://en.wikipedia.org/wiki/Resonant_room_modes

Another of the hobby's little surprises that await you on the way to sonic nirvana.

 

[mike c]

I never liked corner placement. it gives a frequency response that's as flat as the himalayas.

 

[Davemcc]

You've just discovered resonant room nodes!

http://en.wikipedia.org/wiki/Resonant_room_modes

Another of the hobby's little surprises that await you on the way to sonic nirvana.

I did a fair amount of research on room modes and acoustic treatment when I got the sub. The frequency response graph is generally similar from one corner to the other, but in the current location, it is just so much more pronounced. In its original corner, the parametric eq was able to tame the 40Hz peak to a reasonable level. This time I'm not so sure. In the new location, it is nice to be able to see the sub and its beautiful Rosenut cabinet. I guess I'll just have to move a little faster on room treatments.

 

[rexracer]

I won't pretend to know a lot on this subject, but have you tried moving the sub just little? When I first set up my system, my wife was complaining that the sub was "vibrating the floor"... I didn't feel it from my side of the couch. I moved the sub 3" out from the side wall, and she said it was much better. I thought it was a much better solution than turning down the sub.

 

[Davemcc]

I've got more "wiggle room" in the old location, but it hides the sub in a corner behind the arm of the couch. The corner it's in now is a tighter fit (still about 6" from each wall), but at least I can see it and enjoy the beautiful finish of the cabinet. I have an 11' wall dedicated to the front soundstage and it's amazing how easily the equipment eats up linear feet across the front. I will take your suggestion and shuffle things over to give the sub a little more clearance from the walls.

 

[Maceo23]

As Paianful as it is, sometime we have to choose function over form. Ultimately, we all got into this hobby (addiction) in pursuit of the best sound possible. This might just have to be on of the sacrfices to the audio gods.

 

[Davemcc]

It gets worse, but I have a new theory which might make it better. I just put up the rest of my home-made acoustic treatments. At this point, the gain from 60hz to 40hz exceeds 30dB, 74dB @ 60hz to 107dB @ 40hz! So it looks to me like my acoustic treatment is effective down to 60hz and when I raise the gain during pink noise adjustment, the untreated low bass just gets louder. It's clearly time to get serious about bass traps and such.

At 40hz, the beer bottles inside my fridge were rattling together, but that's an issue I know how to solve.

 

[tubesaregood]

At 40hz, the beer bottles inside my fridge were rattling together, but that's an issue I know how to solve.

That sounds like one problem I would love to fix!