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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

Showing 4 responses by totem395

totem395
390 posts
 
As lewm pointed out could very well be a room issue, If you walk around the room, even behind your speakers do you notice any exaggerated 
frequencies?
Does the the issue arise even when not using the sub?

Room treatments may be the solution or hold on to your hats
adding another sub, as in "distributed bass" and room mode
anomalies.

 


totem395
390 posts
 
Having feed back issues and running the table with a cover is 
never a step in the right direction. I can't believe I needed to 
say that.

Step back and look at where the problem begins the acoustic 
characteristics of your room and what you are adding to it.

Start with implementing room treatments rather than
applying this or that band-aid. The gains will far outweigh
other options. 







 




 


totem395
390 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.






totem395
390 posts
 
handymann
 I think proper room treatment, used in the proper way, will give most of us better sound, than an equipment upgrade.
May just have something along those lines engraved on my headstone.

In my book one of if not the most overlooked things that should
be undertaken, the earlier the better. 

The disadvantage being it lessen's the frequency of changing out gear,
tough choice that it is. 


 
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