Need advice with clicking noise from my tube amp


I have a Don Sachs tube preamp and amp.  Recently, I notice a consistent "clicking" noise, about 2 seconds apart, from both of my speakers while listening to my system.  I don't recall the clicking noise changing at different volume levels. I swapped the Sachs amp for two other amps, both solid state, and there was no noise, so I concluded the issue was with the tube amp.  

I took the amp to a topnotch tube tech who listened to it in his system for several hours and did not hear any noise, clearly not the clicking I heard.  The tubes were checked and the biases is spot on for all four KT88's.

I asked Don about the possible cause and he is stumped if it can't be replicated with the amp in a different system.  One possible thought was that the amp is picking up some RFI from some source, but I can't imagine what that source might be.  I don't want to have to build a Faraday cage around my rack, as if I had the KSA's  to do that.  

Any thoughts from you folks would be very much appreciated. 

whitestix

To narrow it down, I would try running an extension cord to another outlet (not on the audio circuit) and see if the problem repeats. 

Gents,

I got the amp back from the tech and have been playing it all day.  The clicking noise is gone, but I'll see if it returns tonight.  I appreciate all the suggestions and will keep my fingers crossed. 

Ain’t hifi fun?  I’ve never had any noise issues for fifty years and last year my new integrated amp started to buzz loudly.  Turns out my wife was using a space heater in the other end of the house.

All the best.

Yea this really sounds like an interference problem. This will be fun to track down….