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.


Hello @agbrace

I have the same problem in the last 30 days.

I also have listened a noise coming from the transformer on the right just behind the volume dial if I put my ear very close to the acrylic cover.

Can you check if yours is also doing this noise?

Mine was perfect for the last 4 years and I am sure it is not normal. (Have change al the tubes for ARC grade Upscale tubes with no change).

Kind regards

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@lcfpimentel No, other than the chime the preamp is very quiet. I do notice though after a few hundred hours on the new tubes and when they’re warm, the chime is reduced. Also it was much more pronounced when I was running it with the Hegel amp which has abnormally high gain.

@tokushi thanks for all the suggestions I will definitely try those. I’ve kind of just gotten used to it at this point. I also have a BAT preamp that uses the 6H30 and does the same thing.