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So Weird- No Stylus Contact Woofer Pumping with Hana ML and Elac PPA-2

I observed the weirdest thing I have ever seen in audio. With the cartridge positioned above the record, tone arm locked up and platter spinning, the woofers were pumping on my system. I googled every permutation of query I could think of but came back with no hits. That’s when I decided to video the problem- link below:

Mystery Woofer Pumping

I could type out all the details but the video pretty much covers everything. I thought ya’ll might be interested in this.

 

mitchellcp
Ag insider logo xs@2x
cleeds
5,947 posts
 

It’s feedback. Move speakers away from turntable.

stereo5's avatar
stereo5
6,385 posts
 

If you can’t get it sorted out, I have a KAB rumble filter that would do the trick.  I am not using it any longer and I could give a good price on it. Food for thought. 

mphipps's avatar
mphipps
6 posts
 

The stylus is not on the record. How could it be feedback? The hi pass filter is engaged on the phono pre. 

lewm
13,030 posts
 

If TT is turned off, does problem go away.? If so then I propose that the spinning platter has some iron content and this is inducing a very low frequency signal in the cartridge which is then amplified and affects the woofers.

mphipps's avatar
mphipps
6 posts
 

The video shows that the platter alone does not cause the woofer pumping 

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