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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
ct0517's avatar
ct0517
1,798 posts
 

lewm - "not likely" means to me; other reasons are more likely and need to be explored.

Until we have more info on his floor structure - its all guessing

*********************************

Audiophile Dance.

keep your turntable motor off.

mute system at low volume. put on a record and lower the stylus on to the still record’s groove.

unmute and start raising the volume level until it is at the high level for your listening habits.

Start to Dance. any dance. jump up and down. Arm waving is optional. Do you hear anything through the speakers ?

Dance around the table to determine if there is bad loading point. If all is quiet ..... that spot is ok.

oh...before finishing..... try yelling at your cartridge (Baritone and Soprano voices) loud to determine if anything comes out of the speakers.


raymonda
847 posts
 
I don't know why I assumed he had an integrated..........just run longer interconnects and keep your amp where it is.  

Having your turntable so close to the speaker is just not smart. Also, do not place your table in a corner after you move your system.

This is the best solution to your problem.
rotarius
426 posts
 
My tonearm is only 32" away from my speaker but slightly behind the baffle. There is no issue with feedback at all.  Airborne seems unlikely from my experience. 
totem395
196 posts
 
lewm
"Start with implementing room treatments rather than
applying this or that band-aid." Isn't there an internal contradiction in that sentence? Some would classify room treatments as a bandaid.

I guess it all comes down to the proverbial "chicken and the egg"

If a room has particular issues ie modes that propagate and are not dealt with any amelioration down the chain is in my mind the "band-aid".
In a studio or other professional venue the first thing that's considered is the room, since that will always be the limiting factor for whatever follows.

Is the room in the OP's case the problem? The way to confirm is to run a sweep and determine where and why the anomalies are present.

Personally the whole room treatment subject is one of the most 
overlooked and discounted topics considering its effect on whatever 
gear, tweaks or changes follow. Thats my take on it.






bdp24's avatar
bdp24
4,908 posts
 
Todd, the Townshend Seismic Platform (the "original" Seismic product, which I have and use, not the current "spring-in-a-bellows" Seismic Pod design) actually IS a slightly inflated inner tube inside a metal frame. The top and bottom damped metal platforms are separated by the inner tube, and it provides, as you say, a lot of vertical isolation. I then have roller bearings on top the platform for the lateral isolation they provide. The combination works real well.
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