Switching off valve amps

[neil]

I am not sure if i have just started to believe something i got told when i was younger or if their is a purpose to it.

I got told that you should turn the volume to zero, then standby for a few mins, then the off button.

Why turn volume down?

Any help appreciated

[Professor]

not necessary. most people suggest just turning the amp off without putting it on standby though i dont know that it makes much difference.

[chuck]

By turning the power switch off first it will discharge the caps....

[jhguitarlab]

If you turn it off with the standby switch in the "play" position it will allow the filter caps to discharge more quickly which can be a good thing if you're going to go in and work on it (YOU WILL STILL NEED TO DRAIN THEM).

If you turn the amp on with the switch in the "Standby" position it will allow your tubes to preheat before whacking them with full voltages which is a good thing (always).
JH

[servant]

Haven't I also read that, as you turn off the Power switch, if you play your guitar while the volume fades it will discharge those caps quicker/more completely??

[zaphod_phil]

I thnk that's true, but I don't know if it's good for the tubes or not....

[Hotrock]

Can I just ask what the standby is for?

Is it for warming the tubes before playing, mainly the amp is on but the link to the guitar is severed? Or is it essentially just a mute?

This has been twisting my melon for a few days now.

Cheers dudes, I'm not trying to hijack the thread, I just didn't think it deserved one all of it's own.

[Newt]

Just the consensus I've picked up, not the gospel:

It's just there for warmup, to loosen up those those electrons on the cathode so they're ready to start flying when the HV is applied. Prevents "cathode stripping."

Don't use it for a mute. When you take a break, turn the volume down; don't put it in standby. So it should more properly be called "warmup", not "standby."

When you are through, cut everything off at once. It's best to let the amp cool as long as you can before moving it, to let things stabilize mechanically from the cooldown.

[bnwitt]

Well here's the advise I got. If you turn the mains toggle off and play the guitar until it fades you will discharge the caps down to a safe level that won't kill you. However, if you in turn forget to switch off the standby switch, there is a good change you will power up the amp the next time with the standby still on and not allow the tubes to warm up properly before hitting them with full B+ voltage and this will definitely shorten tube life. The advice, therefore, is to always switch off the standby first and then the mains and reverse that order for powering up the amp.

The best way to discharge the caps before sticking you hands into the chassis (according to many) is to ground pin #1 of the first preamp tube to the chassis ground for at least 20 seconds with the amp unplugged and all switches on. This supposedly uses the resistance of the tube to slowly drain the caps.