Buzz from inside BHK PRE

[FilTan]

Checkout this thread from last year.

BHK preamp emits high-pitched whine when warm

BHK Pre owner here (since late 2019)… I found this thread while google-ing PS Audio BHK preamplifier whining. I too experienced this problem when I decided to replace the stock vaccum tubes after ~2500 hrs of use. Taking proper precautions, I replaced the Psvanes with pair of platinum grade Genalex 12AU7s from Upscale. I turned on the rear switch and after a minute pushed the front panel switch on and the whining started exactly as in Excelgam video. This whining was NOT audible through the sig…