NAD 3155 Pops when turned off


Have my sons college setup ready to go. He has a set of B&W 685s, NAD 3155, Audinst MX1 and Emotiva speaker cables.
Each time you turn the NAD off you get a pop through the speakers. Volume level does not matter. We spent time cleaning all the rca inputs, power plugs, buttons/knobs with deoxit and deoxit gold. That did take care of a cracking in the left channel when the volume knob was adjusted.

Is there a solution to the pop when powered off? Or is this normal with these older NADs?
Thanks in advance for your help.
blandis

Showing 1 response by gbart

Turn off pop could be the result of some excessive DC offset appearing at the output(s). The DC could be high enough to cause nuisance pops but not great enough to trigger the protection circuitry. This can occur in older amps as parts age and values drift. If the amp has offset trimpots, these can be adjusted to zero out the DC.