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Need help trouble shoot: weird noise

So I turned on my system Friday night. When I unmuted my phonostage, I hear a "D-D-D-D-D" noise coming out of both speakers. This noise coming from analog front only. Digital front is OK.

System: Michell Orbe SE w/ SME arm -> Bent Audio MU step-up transformer -> ARC PH3 SE -> ARC LS-25 -> Pass X350.5 -> Verity Parsifal Encore.

I've isolated the noise to come from my analog front end. At first I thought maybe the tubes needed to be replaced or maybe I've busted a capacitor. Upon some experimentation, I was able to isolate the issue to come from the turntable/cartridge.

I unplugged turntable/step-up from phonostage, and the noise disappeared. I then plugged the turntable directly to the phonostage and the noise is there, but not as loud. When I play an LP, the noise would cover over the music. I thought maybe the cartridge or the phono cable was pickup up radio frequency. But when I changed out the cartridge, lead connectors, and the phono cable, the noise is still there. I am sure this is not the grounding noise, as I had unplug the ground, and I get a different noise (on top of the original noise) when that happened.

Could the tonearm be the calprit? Internal wires broke or picking up radio frequency?

FrankC
gundam91

Showing 1 response by gundam91

gundam91 OP
506 posts
 
It turn out to be the preamp. Somehow wirh DAC powered up, a noise is picked up by the cartridge or phono cable. I tried plugging both sources into different inputs, used a different DAC, to no avail. The noise disappear once I disconnect the DAC from the preamp, or unplug the power from the DAC.

ARC suggests that I try connecting a tape deck to the preamp, and also to swap the tubes in the pre.

FrankC
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