Ampeg SVT VR protect circuit

[g1]

Just leaves a mystery of why the amp was designed with the timer circuit in the first place.

My guess is it had to do with warranty concerns, something not liking the turn-on surge if standby not used, or if the switch welded itself closed. Maybe as simple as the mains fuse value, or possibly initial tube warranty.

I liked the part in that link where he verified the drop-out for low AC voltage, and appreciate how the delay circuit could be a problem in live situations where there is poor AC.