Pop from amp when turning off

[speed3]

I'm having an issue with one of my tube amps "popping" after shutting off. About 1.5 seconds after the amp is turned off, there is a distinct pop from the speaker. There is also a slight gritty hum coming from the speaker when the amp is on. I swapped some tubes out, but that didn't mak a difference. Is this a capacitor issue? ANy suggestions for me to look into?

Thanks for your help.

[ArtG]

I've seen this problem quite a bit. However, it's more common with solid state equipment, although tube circuits sometimes show this issue, often for different reasons. Providing a little more information would be quite helpful. First, you need to isolate the problem to a specific piece of gear. I'm going to assume that since you say "amplifiers". that you may be running monoblocks. If that's the case, then you should short the input of each amplifier, and see if the "popping" goes away. If so, your problem is quite likely further "upstream" in your line stage, switching system, tuner, etc.

After you have isolated the offending unit, I'd start be cleaning all the connectors, switches, and tube sockets and tube pins, with a spray cleaner designed specifically for the job.

This will often resolve the issue. If not, then you will have to look into the circuitry, and check for circuit board cracks, cold solder joints, loose connections, or an obviously charred resistor, etc. Beyond that, it will depend somewhat on your experience with electronics. Unless you have troubleshooting experience on tube circuits, you could be better off by having someone else find the offending component--possibly a resistor or capacitor.

[speed3]

Thanks for the advice. I've definitely narrowed it down to one of my monoblocks. I will take it apart and perform a thorough inspection and cleaning. If that doesn't cure it, I'll look into getting some professional help if necessary.