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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
fstein's avatar
fstein
197 posts
 
Can you wall mount?
miner42 OP
709 posts
 

I can but WAF won't allow.  Plus an +85 lb TT on a wall rack - would not feel comfortable.


I put the REL B1 on an isolation base and this even helped more.

andarilu
23 posts
 
I had a similar issue when I upgraded to the 3d arm. I would start getting a low hum which kept feeding back on itself and getting amplified. I determined that it had nothing to do with vibrations coming through the turntable and everything to do with airborne vibrations hitting the tonearm. I solved the issue by moving my turntable to the side of the room instead of keeping it between my speakers. You can read through the thread I started a while back titled  "Turntable placement".

Good luck.
miner42 OP
709 posts
 
Feedback does not happen when sub is out of the loop.  I do realize the inserts on the mini-HRX feet are rubber - still contemplating replacing those with Symposium inserts.  One other point of contention - the bearing/bell housing on the 3D arm.  I am told the base of the bell housing (where the uni-pivot fits into on the arm) needs to be no more than 1/4" from top of armboard/VTA adjustment base.  Mine was considerably more than that (3/8" approx.).  I lowered mine and readjusted the VTA to bring arm back to parallel with platter then did the fine adjustments.  I was told by VPI the higher the arm is above the VTA base the more unstable it is hence a target for airborne freq.  I have also relocated some equipment and moved sub away from the TT.  All seems well for now.  I guess having my TT set up professionally when I bought it was not the right choice.
woodstock1969
3 posts
 
put all equipment with turntable as far away (another room) from speakers.get awg 8 or10 guage speaker wire and run it to speakers,the further away they are the better and the louder you can play,feedback problem solved(it did for me)
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