Mark V full power/variac switching question

[Dreamtheaterrules]

I recently got a Mark V and have a question about switching between full power and variac modes.

My gut says that if I am in one mode and want to try the other, since "off" is in the middle, that's my clue that I should do a full normal shut down procedure. Go to standby, wait 30 seconds or so, turn it off. Wait 30 seconds or so. Flip it to the other mode while in standby , wait 30 seconds or so, then turn it from "standby" to on.

I've read the manual, and nothing addresses this. My gut says it's not advisable to put it in standby and just flip from full to variac or vice versa. Is this safe? Is it better to do what I'm doing now? Or am I being overly cautious?

 

[SamuelJ86]

I usually switch while the amp is in standby, warming up, and I keep the same way for a session. But I have just switched from full to variac in the middle of practice. I like to put the amp in standby first though. I've had no problems and I switch often, it's been 5 years. Electronics tend to work better if you don't switch them on and off all the time, stuff lasts longer anyway. The biggest stress on electronics is when you first turn it on. So I keep that in mind when I make the switch to or from variac, I switch it as fast as I can, the amp doesn't even blink.

 

[fr0sty]

I always flip between them on the fly, with no shut down or use of standby mode. I've had my V since they came out and haven't had any problems. ymmv

 

[jb's 52]

I always flip between them on the fly, with no shut down or use of standby mode. I've had my V since they came out and haven't had any problems. ymmv

Same here. I figure if it was bad for the amp, Mesa would have it in the literature.

 

[skoora]

I switch mine on the fly all the time. Same on my Stiletto. Never have a problem. The only setting you want to go into standby for is to change to 10 watts as you'll get a nice pop.

 

[Dreamtheaterrules]

I figured as well, that Mesa would warn you in the manual if you shouldn't do it. But it's possible that they figure you should KNOW not to flip it without, at a minimum, putting it in standby. Since the "off" position is in the middle, my thought is that flipping it from full to variac mode is the equivalent of turning it off and immediately back on, which is something else I never do with tube amps. If I flip an amp to off, I always wait 30 seconds or so before turning it back on. Perhaps I'm too cautious, but with the voltages these things run, flipping from one to the other is the same as flipping a regular tube amp from on to off and back on in less than a second, which doesn't seem like a good idea. Perhaps the standby mode makes it safe enough to not need to worry about it.

 

[Nicklotsaguitars]

The idea behind the standby switch is to let the amps heater circuit warm up the valves before exposing them to the whole circuit placing a strain on them. In standby mode the only thing powered is the heater circuit from the power transformer to pins 2 and 7 of the 6L6's and pins 4 and 5 of the ECC83's.
So if you've been playing your amp, the valves have already reached a good operating temperature. I don't see any need to go through the whole shut down start up procedure fully.
I switch the standby out of courtesy to the speaker. It saves those thuds and thunks. Switch the power to whatever mode I need. Then switch the standby back on/in again. Very quickly. There really is no reason to wait.

Also, I do this when changing power modes across channels. I don't use varying power modes across channels it seems wrong to me. Reason being, drastically lowering voltages across the board can strip the valves getter flash. I don't know how Mesa implement the sudden shut off of different valves that is needed for power changes. So I don't vary power settings between channels. As I don't see momentary jumps in voltage across the board as being a good thing. It even says in the manual that the required changes to switch down to 10watts will cause popping. So not to use differing power settings involving say 10 and 45 watts between channels. Though Mesa say it's fine to switch between channels set to 90 and 45watts. I can't bring myself to trust it. Cos I'm all set in my ways and stuff.

I've only measured the difference in voltages between variac and full power mode at the 6L6 plates. 450v in full and 386v in Variac. Which isn't enough of a drop to cause the getter flash to strip, before anyone worries about that.

 

[bandit2013]

I always flip between them on the fly, with no shut down or use of standby mode. I've had my V since they came out and haven't had any problems. ymmv

I have done this many times without issue. The supply caps will remain charged and will not rapidly discharge so switching between windings on the IT should not be an issue. Even when Active or in standby I have done it both ways without any problems.

 

[IronSean]

The whole standby procedure isn't even actually necessary. The damage to tubes by being run when not warm is more of an issue on tubes running 1000+V, guitar amps aren't really susceptible to it. But the Standby switch makes a nice tool for techs troubleshooting, a nice mute for the inevitable speaker pops that would happen otherwise, and guitarists are so used to having them that it's easier to keep using them than to try and teach them everyone that it's actually fine.

My Sundown Artist 100 amp has it's power switch like this: Standby< -- Off -- > Power, and it's not been an issue there.