Audio Research Ref Phono 2SE owners - having hum problems with LOMC/Koetsu Any ideas?


Continuing to have a lot of ground loop like noise with Reference Phono 2SE using .2 MV output Koetsu into Spectral 30SV preamp and DMA-260.  Any ideas?  Feel like I have definitely isolated this to the phono stage as noise is not present on any of the other inputs.  

Note: Due to LOMC, I have to turn up volume to 2/3 for loud music playing and getting lots of hum when no signal is playing at that level.    Up to 1/2 volume, there is very little noise; tempted to move to higher output MC such as Lyra Titan, but Koetsu is near new, only 200 hours.  Have dedicated circuits, grounded together at the box, and disconnecting tonearm cable to phono preamp or taking turntable motor out of the system does not make any difference.

Please let me know of any suggestions or if this is the how the Ref 2SE is.


I had similar issues with my phono preamp and cartridge.  Have you spoken to ARC about it? Kalvin in their service department is very knowledgeable.. Is your phono preamp situated near any other equipment?  How close is it to your power amp?
KAB gain calculator says you only need 64 dB gain, your MC phono has 74 dB so insufficient gain should not be an issue. Assuming you have the cart feeding the MC input on the ARC, I don’t see why you need to have the volume set so high, unless you are in a BIG room with really inefficient speakers and like to listen at concert levels. Spectral components sometimes do not play nice with other gear, maybe that’s an issue. Agree that you should check w ARC.

Did you try any other cartridge? 
Did you purchase Koetsu new?
Did not try other cartridges. Also spoke with Kalvin at Audio Research.  Lifted the ground on the plug but still hum problems.

Phono preamp is clear of everything else.  Any other ideas?
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I am using Benz LP-S (0.35mV at 3.54 cm/s) and Ortofon Quintet Black (0.3mV at 5 cm/s) with my REF Phono 2SE, both of them using high gain setting.  The 2SE is connected to a fully-balanced Bent passive autoformer preamp using XLR.  All components are connected to Torus AVR30 (230V AC).  For normal listening, the preamp is set to around -30 to -20 dB, depending on the records.  No hum, very quiet, almost like solid state.  I can hear slight, faint gain noise only if my ear almost touches the speaker driver.