Having hum issues myself - but minor, I think, compared to yours. Are you running any kind of ground from the TT? Have you checked this ground connection?...also the effects of disconnecting it?
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Yes I checked the ground connection the feed back is the same each with or without the ground.
I also changed my cartridge , thinking it was bad but it didn't make a difference.It's weird because I only get the feedback if I lower the tonearm onto the platter or the record. Turn up the volume to about 10 oclock and I get very bad feedback.
I think there is something wrong with the preamp.
Could be the motor of your tt is putting out enough EM for the cartridge to be picking it up. Might be good to know what turntable and cartridge you have. There are certain cartridges that are known to be susceptible to this.
On the other hand, it could also be that the phono stage of your pre-amp is the issue, or the pre-amp itself is the source.
So, how to isolate?
One idea would be to borrow a phono pre-amp and then plug that into a line level input of your pre. If the hum is still there when you lower the arm, then you could rule out the internal phono stage, meaning it's either the table or somehwere else in the pre.
You might also try lowering the arm onto the record with the tt powered off and/or unplugged, but still using the pre-amp's phono stage. If you turn it up and still get the feedback, the indication is the pre-amp. If it's gone when the t/t is unplugged, then I'd suspect a motor/cartridge interaction. Good luck with the testing.
Thank you everyone for the suggestions.
I couldn't get a phono amp to try but I'm confident it's the phonostage in the preamp. I changed my cartridge to a denon 103r I was using a dynavector xx2 mkII with a vpi aries 3 table and I still get the feed back and if I don't touch the cartridge to the platter and turn up the volume I hear a pounding noise from both speakers.Something else when I first power up the preamp I hear a squiking noise from the left speaker and the driver vibrates in and out with the squeaking noise.
I emailed Supratek a few minutes before posting this .
I'll post what the outcome is.