Booming Tunes

Move the speakers well away from the walls. Alo lower the xover for the sub lower than the roll off of the monitors til they sound right.

You could insert a passive high pass filter (single high quality capacitor) between your preamp and amp with a roll off at 80 hz. Then tune your subwoofer accordingly.

I failed to mention that I do have a velodyne SMS1 and a 300b amp. The amp doesn't do the lower frequencys as well as the sub so the idea is to cross as high as possible and let the SMS handle the 63hz node but most of the good monitors that a set can drive won't get out of the way. I have 'some' room treatments but don't want a room full of trash cans full foam and hair.

Bassbusters (trashcans) are designed for this issue, but IME bassbusters rapidly lose effectiveness as you drop below 80ish hz.

So, you can either:

1) Find an active low cut that you can live with for your main speakers (I use an NHT x-2 instead of the bare bones filter in the SMS1) and use the SMS1 to clean up the issue via subs. This is what I do.

or

2) Find satellite style main speakers that are intended for use with a subwoofer. These have little to no meaningful in-room bass response (and no compensating mid-bass hump) below 80-90hz. You can cross this type of speaker to a sub at a much higher in frequency without actively low-cutting it. (Sunfire Cinema Ribbon Monitors would be one example, I'm sure that there are others.) This way you can cross to your subs using only the subwoofer hi-cut function in the SMS1 and maintain a "pure" main signal path.

Good Luck

Marty

BTW, the Sunfire CRMs are more than decent speakers at their price point, but I suspect that they might be a difficult load for a 300b amp.

Marty