I recently had to do some re-arranging due to an unfortunate equipment failure, moved my Axiom M3 v3s from my main system into the den and purchased a pair of PSB Platinum M2s to replace them. I figured the PSBs would provide a better low end extension, something I often wished my Axioms had. Turned out the PSBs gave me more than just more extension, they also gave a *colossal* increase in overall bass quantity. The amount of bass they output currently puts the 250w dual 10" push-pull subwoofer on the television to shame. I'm guessing this is some sort of room-effect.

Any suggestions on taming this? Unfortunately my placement options for the speakers are limited, and the tone controls on my amplifier sound *terrible* (harman/kardon PM660). Would a equalizer be of use? Or a couple acoustic panels maybe?

If you can I suggest moving the m2s away from the corners into the room a couple of feet. Sounds like boundary effect to me.

I have heard of people putting a resistor in between the tweeter and woofer binding posts, then connecting the speaker wires to the tweeter posts. This attenuates the voltage/current going to the woofer. I've always thought an eq would be a much smarter way of doing things though.

Good luck.

Also try reducing reflective surfaces, like putting a run on the floor, etc.

My Axiom M3V3s gave me too much bass in their corner locations that artificially reinforced bass. EQing helped somewhat but was far from ideal as other freqs were affected as well.

After reading an article here on port plugs, I made a couple of plugs that sealed the M3 rear ports & completely solved my problem - nice, tight bass now in the correct amount.

Unfortunately that might not be an option with yours as the PSB's port appears to be rectangular on the front.

Good luck with your problem...

TAM

Mike, you've mentioned speaker placement and room effect but haven't given any details as to either factor to help analyze what the problem might be. Paul Barton(along with Ian)was among those studying at Canada's NRC with Dr. Toole many years ago and certainly also designs fine speakers. The boominess you've described certainly isn't inherent to the M2s, although it's puzzling why there should be such a huge change from the M3s if the placement was nearly identical. Also, it can be assumed that you're not applying the loudness compensation switch on the PM660, which might inflate the bass response, although not to a "colossal" degree. Another hopefully safe assumption is that the jumpers on the M2s are tight so that the tweeters are actually in operation.

With just the present info it can be pointed out that to minimize the room boundary effects on bass inaccuracy the centers of the woofer cones should be at unequal distances from the two walls and the floor.

John, the OP mentions having to do re-arranging due to equipment failure. Not sure if the whole room was moved around or what. Hopefully this will be clarified.

Richard

The speakers were more-or-less in the same position as the Axioms were. I've now moved them in away from the side walls another foot and forward about six inches, which is about as far from the walls as they can go. It's helped somewhat. There was previously an equipment stack in between the speakers when the Axioms were in place, I can't imagine it would've made a large difference. As for the room itself, there is already a thick wool area rug that covers about 2/3rds of the floor, but the walls around the speakers are more-or-less bare of anything sound absorbing. A floor to ceiling window that runs 4/5ths the length of the wall behind the speakers probably doesn't help. The amplifier itself shouldn't be a factor as it's generally run with the "main direct" function enabled, it bypasses pretty much everything except for the volume and input selection.

Did the seating location change? Bass peak perhaps? Standing wave issue?