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Parasound JC 3+ Phono Preamp Hum

I know hum problems have been discussed ad nauseam on this board, but after trying a few different things, I have been unable to find a solution. I recently purchased a used JC3+ to replace a PS Audio GCPH with Underwood Mods. Although the GCPH had some hum, the volume had to be turned up to past 50% before it was audible.

With the JC3+ I get a low hum at 25% and loud hum at 50% volume. What I am describing is with everything on, no record playing.

The SL1200G TT is grounded to the JC3+. I’ve tried the following: 1. Added a ground wire from the TT to the integrated chassis, a Cayin A-88T Mk II. 2. Changed cables from TT to JC3+. 3. Changed cables from Integrated to JC3+. 4. Plugged JC3+ directly to wall outlet. 5. Changed to AC polarity on the JC3+ via the switch on the back from normal to invert. 6. I’ve tried using no ground wires.

Due to my cabinet configuration, power cables and audio cables run parallel and close to each other. There is no way I can arrange them to be perpendicular to each other.

If I lift the tonearm and let it fall back on the cradle, I can hear the echo or bump through the speakers.

My cartridge is a Hana SL.
Cables: TT to preamp, Silnote Morpheus
preamp to Integrated, Morrow MA4 (and tried AQ King Cobra)

Everything is plugged into a rather inexpensive, basic Belkin PF30 power strip.
I have been considering upgrading to a AQ Niagra 1000. Not sure if that would help with the hum.

The JC3+ is definitely a better sounding preamp than the GCPH . I can’t hear the hum when playing music, but I’m quite disappointed that the JC3+ hums louder than the GCPH.

Again, I know hums have been discussed to death, but any ideas or suggestions for my specific problem would be appreciated.
Eric

ericsch

Showing 1 response by helomech

helomech
1,525 posts
 
I own a Hana SL and JC3 Jr. I only get a very low level "hiss" above 50% on the volume knob -- far louder than I’d ever listen.

Have you tried any other cables between the TT and preamp? Is the Sillnote Morpheus shielded and designed for low level phono signals?

Cable spacing may be the issue, but in the past, I’ve run phono cables (even cheap ones) quite close to power cables with very low to zero noise. More often, the noise is a cartridge -- turntable interaction issue, (like Grados on a Rega), a loose connection, or a faulty cable. I’ve now owned three pairs of defective Audioquest cables, so even "good" cables can be the culprit. I had one of their tonearm cables that caused hum simply because the spade lug was poorly crimped to the ground wire. You might also open up the JC3 and check for any loose connections. 

You’ve tried bonding the turntable to the integrated but have you tried bonding the preamp to the integrated AND preamp to the turntable, using short bonding wires? That won’t likely solve your problem but it worked for me in a couple setups.

Double check the quality of connection between the cartridge and headshell. If you’re using an aftermarket headshell, that’s another potential problem area. I’ve had an aftermarket headshell with a neck that was just barely to short to allow good contact between the mating pins. Lastly, make sure there’s a good distance between preamp and any components with large transformers (that would include the 1200G).
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