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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
miner42 OP
709 posts
 
Thank you to everyone who has contributed their thoughts.  I will start by removing the cones and allowing the platform to sit directly on the isoblocks. I will also move the right speaker a bit at a time to see if I can eliminate those airborne vibrations.  I think I know the answer but will ask anyway - would keeping my acrylic cover on during sessions help or hinder my issue?
rotarius
431 posts
 
If you have sound waves affecting playback, the cover should help (I doubt that though).  It should not be a hindrance  either way.
yogiboy's avatar
yogiboy
5,461 posts
 
Try it both ways and see what happens!
raymonda
855 posts
 
You might be getting airborne feedback as well as mechanical. I, for one, would never place my table behind and so close to a speaker. It is a recipe for disaster. 

Run longer speaker cables and move your source away from your speakers.
lewm
12,451 posts
 
No cover.  The cover itself will resonate, if the issue is airborne, and could make matters much worse.  As a general rule of thumb, I would never ever use a cover during play.  The stylus/LP interaction itself elicits vibrations that are best dissipated, not trapped under a cover.

Having said that, try it. I am interested to know whether my negative feelings about covers are operative in this instance. I have five turntables and none of them has a cover except the Kenwood L07D, which has a clever lucite, LP-shaped cover that sits down over the spindle directly on the mat and not over the whole top surface.
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