When I turn the standby to "off" I get a fairly loud "pop"

[wrxplayer]

Should I be concerned? If so, what might be the fix? I just swapped out the pre-am tubes, which reduced transient hiss.

Amp is a Blankenship FBWSC, kind of a mix b/t Super Reverb and Tweed Deluxe.

 

[RussB]

Has it always done this? If so, a capacitor across the standby switch terminals will cure that. If not, perhaps the standby switch needs replacement

 

[pdf64]

How about not using standby? If the amp has a tube rectifier, standby has no technical benefit, but rather the potential for drawback.

 

[jay42]

Basically, this is the inevitable end of most Standby switches in Fender amps and any amp with a similar setup. When I replace them, I put a .1uF/600V cap across the connections...Carlings are narrow. I've been in amps where a previous tech bent the lugs. Not the worst idea.

 

[robrob]

Merlin, The Valvewizard suggests a resistor across the standby switch terminals to eliminate the pop. It also eliminates the inrush current when you close the switch because it allows a 'trickle charge' of the filter caps. I do it to all my amps with standby switches.

 

[ffoont]

Would the same type of fix apply to an amp with switchable output? My Blackheart amp has popped loudly when switching between 15 and 7 watts since new. It would be nice to put an end to that.

 

[EADGBE]

Could this be caused by a bad filter cap?

 

[robrob]

Would the same type of fix apply to an amp with switchable output? My Blackheart amp has popped loudly when switching between 15 and 7 watts since new. It would be nice to put an end to that.

That output level switch is probably a pentode / triode switch similar to this Bassman mod I did to my 5F6A build. It pops too but I don't think there's much you can do to prevent it due to the instantaneous change in power tube screen voltage when the switch is flipped.

 

[ffoont]

You're right, it is a pentode/triode switch. Thanks for the reply.