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Speakers "pumping" with record warps - normal?

I just set up my Technics SL-3200 with an AT440MLa cartridge, Sumiko headshell, and Herbies mat. The table is properly isolated on a Target shelf that is mounted to wall studs. Using the Hi-Fi News test record, I determined that the resonant fequencies of the tone arm are approximate 8Hz (vertical) and 7Hz (lateral).
I've noticed that on warped records, the speaker cones do a lot of low-frequency pumping (visible movement in and out). I'm afraid that I could damage the drivers if I turn up the volume. Is this a normal consequence of warped records, or do I have a resonance problem with my TT?
Thanks,
Mika
mwaller
pauly
1,012 posts
 
Yep it's 'normal' (I use the term normal very loosely) and you could most certainly damage your speakers.

You can solve the problem by using a rumble filter - KAB makes quite a nice one that doesn't cost an arm and a leg.

Regards
Paul
ablang
165 posts
 
I had this problem when my table was just _slightly_ off level due to a platform settling. Leveled it again; problem gone. Hope yours is that simple!
Ag insider logo xs@2x
rauliruegas
13,084 posts
 
Dear Mika: I think that it because of the same trouble that you already posted where I give my advise:

http://forum.audiogon.com/cgi-bin/fr.pl?eanlg&1208189480&read&3&4&

The Ablang post is a good one tp check about.

Regards and enjoy the music.
Raul.
mwaller OP
17 posts
 
Hi Raul -
I've measured the reonant frequency of the tonearm/cartridge combo - it's roughly 8Hz (at the low end of the desirable range).
If I want to increase the resonant frequency, I'd have to find a cartridge with an even lower compliance... is there such a thing? I thought that the AT440MLa is about as low as the come... any recommendations?
Mika
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