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.


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.

This thread highlights the diversity of sensitivities we have to various noises and operational issues. Some manufacturers really need to add an alternate "high sensitivity speaker" reference rig to expose noise issues. Not ARC though - they’re doing just fine; their tube gear is already as quiet as can be wished for, in the ways that count.

Reports are consistent that 6 => 6SE upgrades are currently VERY fast. Anyone who’s thinking about it should take advantage of that now. The out-of-warranty repair queue is more concerning...6 months? Don’t send your 6 or 6SE in for the 6H30 ping-tshhhh "issue". Btw it’s really a long decay on that "tshhhhh" part - that’s the 6H30 for you. New set of tubes at most. I guess it’s possible if your PCB board is coming loose somehow, that could exacerbate the 6H30 / relay noise. Everything needs to be tight inside.

I don’t expect the 6SE upgrade would impact the 6H30 microphonics or the output impedance. It’s purely for quality of sound.