The Correct Way to Use a Standby Switch

Here's a quick rundown on the proper way to use a standby switch on a tube guitar amp. Comments below are more than welcome. The amp used in this video was the very first prototype of the Auburn Troublemaker, so that's why it looks like, well, a prototype.

[teye-master]

My father who built tube amps before WWII always used the following rule of thumb: every time your tubes go thru a complete cool-down/warm-up cycle, it shortens their life approximately the same as when you leave 'em on for an hour. So, if the break in a performance or rehearsal or recording looks it's gonna last over an hour, I switch the power off. That is what I do, and everybody has and should have their own ritual. It's like taking sugar in your coffee: there really is no right or wrong. I LIKE to have a standby switch on my amps and have put them on amps that didn't have them. I personally also like to drain the caps by switching off first vs messing with bleeding them before amp work, which I then do anyway just because of some previous experiences... BTW Auburn Rob, I've seen a few of your vids and am convinced you know what you're talking about. Wish everybody a great day.

[gwgwgwgw]

I've been playing for 50 years and didn't know that! Thank you!

[PeterDad]

My Marshall 2245/JTM45 that has a GZ34 rectifier tube and the owners manual warns to always put the amp on standby before shutting off the power. So I do what the owner's manual say's to do. I am aware that by shutting off the power while still in standby that you discharge the capacitors by allowing them to bleed down, and that is a safety feature to protect me when I open up one of my tube amps.
I allow about 3 min. up to 1 hour (very rarely) on standby to warm up not only the tube filament but also the metal chassis. I am also aware that when I play my tube amps for many hours that the entire head (chassis and tubes for combo amps) warms up and the heat has the effect of drifting the caps and other electronic components out of spec. That's why your tube amp has a different character when played for many hours. Mine sound really good after 9 hours and even better approaching 14 hours. I admit that during this time I take breaks and often I put the amp on standby. Sometimes for shorter breaks I only lower the volume and gain knobs. Which limits how many times my tubes are exposed to a voltage spike by not using the standby switch. There was a time when I would lower every knob when not playing and especially when powering off (I still do that most of the time). I love my tube amps, to me they are alive.
I do the same for my Fender '59 Bassman LTD and it has the 5AR4 rectifier tube.

Recently I started using a Variac and start up my tube amps at from "0" vac, then move the dial until the red jewel light starts to glow at about 40 vac. and then slowly move the voltage upwards. I can run my tube amps at around 95 vac to 110 vac. This protects every electric component in the amp as the voltage is applied slowly and rises. I could even start at 40 vac for the components to really be healthy.
Some amps the non tube amps and the Bugera tube amps that have an automatic voltage regulator will not run at 90 vac so I do use a normal 120 voltage. For my tube amps (all of them) 105 vac is very good the amps sound terrific and I am lowering the plate current and even the mA for the tube bias to a very safe level. Not only do the tubes last longer but to my ears the amps sound better. After 12 hours on reduced voltage my tube amps are heavenly. That's why I shall always be a tube amp guy.
Once I used a small tube amp as a space heater in my bedroom because the floor was above a crawl space and was always ice cold and I wanted to break in/condition all components to last a decade as a min. So far so good.
I am not an expert. I am not a tube amp technician either. I just love tube amps and search out any knowledge concerning them.
Your advice is the advice that I shall adhere too as you made the most accurate assessments out of the many Youtube video's that I have watched on this subject. I thank you for your advice!.
I came here looking for an answer to this question: When taking a break Is it better to put our tube amps on standby or to turn the volume and gain and possible the preamp tubes (EQ section) to a min setting? Do tubes last longer when not turned on and off in standby mode many times in each day long playing session? -Peter
P.S. Looks to me like you make guitar tube amps could you talk a little about that? Please? Hey tomorrow is Tuesday New Years Eve day December 31, 2019 Happy New Year everybody!!!!
I edited this a little bit on July 22, 2023 because I had made several incorrect statements. I have more knowledge now and also a better understanding of all this thanks to all the Youtube commenters and especially those that take the time to make an educational video.
- Peter age 73

[jimmyjames]

Thank you great information I know this is a very old video but you explained it correctly. There's too many videos that don't make sense and say that standby is a myth and doesn't mean anything. That makes sense appreciate it!

[e.c.]

I tried turning off my 5150iii this way once (unintentionally) and got a bad nasty sound. Thought I broke something. I always power on and off in standby. Also, if I don’t let the amp warm up enough in standby and rush things, I get crackling sounds coming from the speakers. So I always let the amp warm up for a good long while....over a minute - power on, get guitar out, hook up cable, tune it, etc - then take it off standby.

[MidlifeRenaissanceMan]

The other reason to power on in standby mode is to let the bias come up (down) to the correct voltage. The bias is often obtained by taking a tap off the main B+ and feeding it through a resistor divider. This can take a few seconds for the bias filter caps to charge up and for the bias to reach the correct negative voltage. This results in an under biased output stage. My old Marshall JMP "Rocker" I just scored does this. The bias circuit is fed before the standby switch so it comes up to voltage with the standby on. I've measured the plate current and there is a surge when the amp is cold powered.

This standby switch thing was a hang over from RF transmitter tubes that run on 800V - 2.5KV or more where arcing in a cold tube was a reality, audio tubes running at 300V-500V it was less an issue, however, early "commercial" Russian tubes from last century had the same arcing problem and often needed to be burnt in, before you could just fire them up cold.

One other thing to mention is cathode poisoning if you leave your amp on standby for extended periods (hours, days, weeks) The theory is that the electrons leave the cathode but don't have anywhere to go and so, rejected by the negatively charged grids, and ram back into the cathode. This slowly changes the chemical composition of the the cathode and surrounding _hardware_ in the the tube and it becomes less efficient.

Switching an amp to standby between sets is fine. Leaving it like that overnight, probably not so wise if you want your tubes to last.

[kiillabytez]

Just received my Marshall DSL 40CR, and read the Quick Start Guide. It doesn't say anything about engaging the Standby switch when powering On/Off the amp. It just says to ensure all speakers are proper and turn all the Master Volumes to 0 and plug in your guitar before turning the amp on. The only mention is to reduce the power level from 40W down to 20W or to place the amp into standby mode. This is directly from Marshall themself.
The design on my amp won't let you change power modes without engaging the standby because it's a 3-way rocker switch with the standby in the middle position.

[Aer]

My hotrod deluxe makes a loud cracking noise if I turn it off while it’s that hot. I usually use stand-by to cool it down before shutting off.

[michaelinglis]

I own a DSL100HR but heres an excerpt from the DSL100H/ DSL50C Manual that im sure still applys to the new HR version and any other Marshall amp with SS rectification or Tube rectification. Its specifically states to power off standby before the mains power switch which i can imagine is for multiple obvious
2. Standby Switch
Controls H.T. or high voltage to the valves to allow
them to attain correct working temperature before playing.
To prolong the life of the valves it is always advisable to
switch on the Mains Power Switch (item 1) about 2 minutes
before switching on the Standby (item 2).
On switching off, the Standby should always be
switched before the Power Switch.
The standby facility is particularly useful between sets
and before playing, as it allows you to keep the valves
operating at a functional temperature but without any sound
being produced

[MM-rrkp]

My 90s Ampeg t
Reverberocket owners manual recommends the following for using standby
Standby switch activates the
amplifier when ready for play.
Always turn this switch off first,
on last. Turn the Power switch
on at least 30 seconds
before turning on the Standby
switch
Which would you suggest? I believe there is a circuit board
Also, when put it standby then power off it is quiet, if power off first in play mode, an electrical type noise, kind of a pop and then some electric sounding noise on next startup

[CatharticGuitar]

I’m guessing this would be the recommended procedure for a fender 65 deluxe reverb amp reissue (2017). It does have a rectifier.

[THUNDERWORX]

Makes sense to me. I've always turned my amps off with the standby on normal as your video shows for that very purpose (draining caps). If you hit a chord, it sounds like the amp is using its last volt trying to make sound, so it sounds like it is draining something. I have heard that this drain method just works if tubes have been heated up good. If I am working on an amp, I always test and ark everything just to make sure anyway. With all of the conversation going on regarding the standby, if nothing else, it is a quick way to leave your amp on idle for a few minutes while doing something else without having to wait for tubes to reheat upon return.

[waynegram]

Leaving the Standby Switch turns ON give the filter capacitors a PATH to ground to drain off the stored charge? I'm not sure if all standby switches are wired up like this for various amplifiers brands and models. The Standby Switch was so that the Biasing Circuit was stabilized BEFORE you applied the HV plate voltage and also the standby switch is to make the output tubes have a long lifespan when cool down and warm up cycles.

[briansmythe]

Cool Thanks I just got my first Valve Amp Was wondering what the Standby Switch is for Exellent
Like your Car Bro looks Nice from the Inside any ways

[JirkaMichalik]

I just got the Blackstar St. James amp and I am surprised that there is nothing about the wait period between turning the power and standby switches on.

[joeygwood]

This video is gold! Thank you for sharing this info.

[cantina]

20 seconds to warm up an amp? I usually wait for 10 minutes

[wingnutmcspazatron]

I play thrash and I can't get that crisp, demolishing Slayer tone until the tubes have been aggressively played through for over half an hour 😖 but when they finally cook through, it's so worth it.

[littlebritain]

Hi, does "in play mode" at 03:00 mean that power switch is "off" and "standby" is in "normal" position?

[davidkhammer]

How did you do that demo while you were driving. Pretty impressive. HahahAha. Actually I am researching the stand by switch as one of my friends has put my whole way of thinking on its ear. Thanks for the explaination. Makes sense. It’s to save the caps not the tubes