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Feedback through turntable

My system consists of a McIntosh C2300 preamp, MC452 amp, MCD500 SACD player, VPI Aries 3D with Ortofon Cadenza MC cartridge, Manley ChinookSE phono stage, PS Audio P5, Sonus faber Cremona Auditor M speakers and REL B1 Sub bass system.  My issue is with turntable use only; SACD has no issues.  On my pre when volume is +55 (peak at 45watts) I start to get feedback through the turntable - a sort of low freq sound, back off volume and it goes away.  My Auditor M speaker is about 3 ft away and in front of turntable.  I do have a rumble filter (KAB) installed between preamp and phonostage to help with sub woofer pumping.  Due to room layout I cannot rearrange the setup/move turntable.  My turntable is on a 2.5" block of wood and that sits on 4 isolation blocks via spiked feet.  Any thoughts how I can eliminate this problem?  Harry Weisfeld with VPI states he has 4 15" woofers (JBL Everest) near his Prime Signature setup with no issues at all.  Why am I having this problem and how can I eliminate it?  Thank you in advance for all feedback.
miner42
bdp24's avatar
bdp24
10,302 posts
 
I'm planning on trying those springs myself slaw, in combination with roller bearings.
miner42 OP
709 posts
 
I will be trying positioning the speakers and moving the TT a bit.  The more I think about this the more I feel the problem is airborne.  I may go as far as plugging the rear ports on the Audito Ms first to see if that helps.  Thank you to all who have contributed.
toddverrone's avatar
toddverrone
840 posts
 
You may find that seismic isolation can benefit airborne resonance issues too. Though only because it would allow the rest of the table to vibrate and dissipate the energy.. 

A cheap way to experiment is to use a small, partially inflated inner tube under the platform your TT is on. Simple and effective against some horizontal and many vertical vibrations. Though, if you've already ordered the springs, you may as well see how that goes.
ct0517's avatar
ct0517
2,041 posts
 
 I feel the problem is airborne.

not likely

have you performed the audiophile dance yet to vet placement ?

in order to give recommendations we need to know what your floor is and how it is supported.  Wood floor with wood suspended beams, concrete pad, etc....  can you give some detail. 

stringreen
...... and I can do back flips, and never get feedback from the turntable.

how 'bout posting a youtube showing this ?


lewm
13,814 posts
 
CT0517, I have no dog in this fight, which is to say I am only guessing that the problem IS airborne.  I certainly could be wrong, since my opinion is based only on the paragraph submitted by the OP.  But can you say why you think the problem IS NOT airborne, with such conviction?

Rotarius, There is no harm in trying the cover, I agree.  But in general, I would never run any turntable with its dust cover in place.  This is based on trying it both ways, over many decades and with several turntables. Could it help in this particular instance? Maybe.  Anyway, trying the cover would tell us much about what is going on; if the cover makes a difference (for better or worse), the problem probably IS airborne.
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