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.


The single ended connection between the Ref6 and H20 appear to be much more cooperative at 300 ohms / 50k ohms. 

Wow, that's a world of difference. I believe Ref 6's circuitry is optimized to normally be best from XLR outputs (whether using SE or balanced sources), but yours might just be the rare scenario where SE wins. You might ask ARC what they think of using a Jensen ISO-MAX XLR-to-RCA transformer box to potentially get the best of both worlds here. That still won't address the tube chime issue lol. 

I call it the 6H30 Zing… not a worry! Enjoy the music!

Doesn’t the Ref 6 have essentially a built in attenuation? My LS 26 has low, mid, and high gain settings via the remote. I know the Ref 3 and 5 do as well. It also has the ability to choose SE and Bal connections. ARC pre’s are notoriously over driven given the range of “volume” they allow. Some actually send them in and have ARC reduce the gain in the entire pre.

@agbrace   What do u mean u hear a chime ? Can u explain that chime sound you are hearing coming through the speakers? I have owned the Ref 5se , the Ref 6 and now the ref 6SE. I was using a Krell FPB 600 amp now I am using the Audio Research Ref 750s. I have NEVER heard anything but dead silence   

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.