My 2a3 amp has been working well untill the last couple of days I turn it on and after about 10 seconds it makes this noise like a needle has been draged across a record it doesn't last very long less than a second then everything is fine . I changed 6sn7gtb which is the driver for the 2a3 for another one and the noise is gone . It only happened one one channel and was curious if anybody could tell what causes this .
Thanks
nigel
Thanks
nigel