ARC Ref 6 Tube Microphonics

Hi All, I purchased a used Ref 6 preamp a few months ago, initially everything was fine, tube hours indicator said ~950 hours but not sure if that was accurate. After about 50 hours of use, turning the volume past 0 and the mechanical relay kicks in, a chime is heard coming through the speakers. I assumed one or more tubes had become microphonic. I replaced all tubes with new ARC select from Upscale, 7 Sovtek 6H30Pi, 1 Sovtek 6550WE. I let it warm up for a few hours, turned volume past 0 and the same chime is still there. On the positive side, the SQ improvement was immediately noticeable and outstanding, I love the preamp in my setup but the microphonic chime is annoying. ARC service said that some chime is normal but it still bothers me. Any advice? Ignore it? A new set of tubes direct from ARC? New tube rings? Send in to service? Thanks.


OP/geof3 - I use a Ref3 into a Threshold S300 II, which is fairly low gain, but I've never ever, even with my old amp which had much higher gain, heard any kind of 'chime'. I've even just 'thumped' on the top cover to cause some vibration, and, silence, even with the volume at 50, which is around my normal listening position (range from 40→60).

When you say you hear a click of a relay when you turn the volume from 0 up; that's another thing that absolutely doesn't happen on my Ref3. Going from zero up, it's silent, completely, even with my ear next to it, there's nothing. Relay operation can only be heard when changing sources, never from Vol-0 up/down or anything in between, so if your makes a relay clicking sound when going off of zero, then I would do as suggested and send it to ARC for repair

And, geof3, the Ref 3 absolutely does not have a variable gain setting, as you say, either on the remote or the unit itself.

Hey, I am not sure how physically close to an ARC dealer you might be. Try borrowing a Ref 6 or even better the SE version and hear if it happens with the demo. I have the 5SE with the Luxman M10X. I bought them in that order. Maybe your 6 does not match the H20. But the 6se might. The impedance or the voltage is different. I will tell you I not my friend who has a similar setup (both SE) have had this issue. I say borrow the demo from the dealer and email ARC at the same time. 
Just an idea to help. 

@tattooedtrackman It sounds like a small high pitched cymbal hit due to the vibrational shock of the relay transmitting via the PCB I suppose. It only happens when coming off of volume 0 when the relay kicks in.

@hsounds Thanks, I will try that, also I wonder what ARC is charging for a 6 -> 6SE upgrade??

$5K for upgrade. They now have a dedicated person dining upgrades, so the turn around is fast. Well, it was two weeks a couple months ago.


The 6 and 6SE is exactly the same preamp with upgrades in a number of components.

I’ve been using Audio Research preamps for thirty years while swapping other components and never encountered any kind of incompatibility or noise.