Power Comsumption with Amp on Standby

[Ayrton]

Re: Power Comsumption with Amp on Standby

My amp tech told me that standby is for warming up the amp only, and that going back and forth between 'on' and 'standby' causes a lot of stress on the power tubes. Warm it up, leave it on for as long as you're using it, shut it off all at once when you're done.

For breaks up to like 15 mins, I either turn the guitar's volume down or unplug from the amp's input. Any longer than that, just turn it off.

This...

John Suhr and Dave Friedman both told me the stand by the switch is pretty useless. I just flip both switches when I fire up the amp and only use the stand by for short breaks.

[Gtrjunior]

Re: Power Comsumption with Amp on Standby

My small Blackstar HT-Studio 20 doesn’t have a standby.

[oneblackened]

Re: Power Comsumption with Amp on Standby

Power consumption at standby can (roughly) be found by figuring how much heater current the tubes are drawing in amps multiplied by the heater voltage. B9A dual triodes (i.e. ECC8_/12A_7) tubes draw roughly 300mA per tube at 6.3V. 6V6s draw about 500mA per tube, EL84s about 750, 6L6s/5881s about 900. EL34s and their similar analogues (i.e. 6CA7/KT77) are all in the ~1.5A per tube area, as are 6550s. KT88s are 1.6A roughly. Rectifier tubes also use heater current, though usually from a 5 volt tap. 5Y3s and GZ34s/5AR4s draw about 2A of current per tube, while 5U4s draw about 3A.

For an amp like, say, a Soldano SLO, without taking transformer losses into account you're looking at 5 12AX7s (1.5A total) plus 4 6L6GCs (3.6A total) for about 33 watts of power used just by the heaters.
For something like a Blackface Deluxe, you'd be looking at 4 12AX7s, 2 12AT7s (~1.8A together), 2 6V6s (~1A together), and a GZ34 (2A) for around 28 watts of power used just by the heaters.

This doesn't take into account that leaving an amp on standby all the time will severely reduce the life of your tubes - cathode poisoning is a major problem when you leave an amp on standby for long periods of time.

[Jacew]

Re: Power Comsumption with Amp on Standby

I wouldn't call standby completely useless: I mean, if tubes are cold I would definitely keep it on standby for few mins before cranking them on their output limit: Running a thing made of metal and glass half hot and half cold simply can't be good for longetivity! It's not deep electrical knowledge, just basic physics.

[Ayrton]

Re: Power Comsumption with Amp on Standby

I wouldn't call standby completely useless: I mean, if tubes are cold I would definitely keep it on standby for few mins before cranking them on their output limit: Running a thing made of metal and glass half hot and half cold simply can't be good for longetivity! It's not deep electrical knowledge, just basic physics.

Basically what they were saying is warming up the amp with the "On" switch was the same as using the stand by. I flip both switches and then give it a few minutes to warm up.

[DonP]

Re: Power Comsumption with Amp on Standby

As soon as standby is flipped on, the B+ it trying to pull electrons from the cathode. If the cathode is not heated, it will be cold stripped, causing damage and shorter life.

I say warm up with the standby off, then flip on after the cathodes are heated.

[dpaterson]

Re: Power Comsumption with Amp on Standby

Found this while looking around for something else on Sweetwater's site and remembered this thread:

https://www.sweetwater.com/sweetcare/articles/great-standby-switch-myth/

(Edited. Wrong link. Sorted now.)

[bldrst]

Re: Power Comsumption with Amp on Standby

Found this while looking around for something else on Sweetwater's site and remembered this thread:

https://www.sweetwater.com/sweetcare/articles/great-standby-switch-myth/

(Edited. Wrong link. Sorted now.)

Excellent article, explains a lot and clears up some misconceptions. Thanks for the link!

[FuseG4]

Re: Power Comsumption with Amp on Standby

I'm so used to standby switches on the back that every time I start up my Princeton (no stdby as the rectifier warm up handles same job) I keep feeling around the back for a second toggle switch and then I'm like.... Wait.... Oh yeah!! Did this again last night and it reminded me of this thread lol

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