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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
ericsch OP
180 posts
 
I just wanted to follow up and let you know that I received my JC 3+ back from Parasound last month and they found no problem or defect with the unit. With that reassurance, I am going to review and try some of the suggestions you guys recommended. Thanks to all for your responses.
last_lemming
407 posts
 
Eric,

 I posted earlier on and suggested trying another headshell and/or running a long extension cord to another outlet in the house. As I stated earlier for whatever reason one of my hums had to do with the pins on the head shell on my 1200gr tone arm not connecting - just try it, you don’t have much to lose. Also for whatever reason when I ran a power cable from the phono pre to another outlet across the house the problem went away in another hum situation, this is at least worth trying since its relatively easy as well. 
twee-k's avatar
twee-k
1 posts
 
Eric,

I haven’t read through this entire string, so maybe this was covered above, but will say that I’ve moved to a new home (new to me) and I’ve been chasing a grounding hum in my system for about a month now. I finally figured out the Parasound was the source of the hum.

Gear and History:
GoldenEar Triton 2+ with AQ Rocket 33 cables, Synergistic Research PCs
Line Magnetic LM-518ia acting as a power amp, PC=AQ HC Hurricane
Pass Labs HPA-1 acting as a 2 channel pre-amp and headphone amp, PC=Kimber PK10
Ch1: Parasound JC3+, PC=stock/Linn Sondek LP12 w/Lingo
Ch2: Auralic Vega DAC/NAD M50.2 media player, both using Shunyata Delta NR
Power: Wall Outlet: AQ NRG Edison, Conditioner: Shunyata PS8 with Delta NR to wall

I had a fixed ground hum regardless of whether I was using the JC or the Digital media. If I ran the LM as an integrated amp and bypassed the Pass Labs the hum would be modest and I could live with it but didn’t like it. I tried putting a cheater on or unplugging a number of different things in my listening room and could not find the root cause of the problem. When I ran sources to the Pass and ran the pass pre-amp out to the LM pre-in the hum was boosted to a level that made it intolerable.

Randomly, while not playing any music and hearing the hum I unplugged the Parasound and the hum completely left the speakers. I then took the cheater plug and put it on the Parasound and plugged it back in. Nothing!

I realize the problem is the power in my new residence but what I don’t understand is why the Parasound is the only component affected and is there anything I can do short of using a cheater to fix the problem.

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