2. analog
  3. 1256605343

Woofers getting workout, but no bass

I'm puzzled: I'm noticing just about every LP I've played in the past couple days has my 10" woofers moving like mad, but not in time with the music and regardless of whether there's any audible bass.

I can only conclude that I have subsonic frequencies occuring (my phono stage doesn't have a filter). What would cause this?

Relevant components:
Speakers: Wilson Sophia 2's
Turtable: TW Acustic Raven One
Phono stage: Tron Seven

Thanks in advance.
madfloyd
acoustat6
357 posts
 
"11-01-09: Vandermeulen
I just look at mine when they do it...and it hypnotizes me. INTO WANTING MORE EQUIPMENT!!"

Want more equipment?
Try a subsonic filter

Bob

warjarrett
105 posts
 
Definitely, you are reproducing the record warps. You need a subsonic filter. Your amps are using a lot of power to reproduce frequencies that you cannot hear, and that you don't WANT to hear. Also, if you are using a heavy arm with a high-compliance cartridge, this makes the problem even worse.

Tell us what cartridge and arm you are using together.
warjarrett
105 posts
 
Oh, I just found your answer. The Triplanar/Dynavector XV-1s is a fine combination. So you simply have warped records and a system that reproduces 3 to 10 HZ very accurately. You need to insert a subsonic filer.

Sounds that you can hear, you cannot see. If you see your woofers moving, it means you are reproducing frequencies that should be filtered out.
sm2727
115 posts
 
Could be feedback. If you put the needle down on a record that is not turning do you still get woofer movement? May have to move your turntable. I had the same problem and that fixed it.
shadorne's avatar
Ag insider logo xs@2x
shadorne
7,477 posts
 
Very likely it is simply a matter of ported speakers and the sound is lower frequency than the port tuning frequency on the speakers.

When you have sounds below the tuned port frequecny of your speakers then the woofers flap around uncontrollably and make almost no sound, which is exactly what you have. Sadly, this flapping around will add plenty of IMD distortion to any music you play becuase the speaker drivers are operating way way outside their linear range when they pop out of the speaker in the way you have observed - look for a big port on your speaker probably tuned around 30 Hz to maximize bass extension...

Either you can filter out all the LF electronically or select a different design of speaker...
More to discover