Turning off amp without standy switch

[LeadPaint]

Occasionally I forget to turn my amplifiers to standby before turning them off, I just hit the power switch. The amps have survived this so far.

Is there any danger in directly turning off a tube amplifier?

 

[Greg_L]

Not so much turning one straight off, but flipping it back on without being on standby could potentially hurt something.

 

[ShanPeyton]

-wrong thread-

 

[miroslav]

Well...there ARE tube amps without standby switches....and they never blow up or anything like that...just turn your main volume down to "0" when going On/Off.
I had one without a standby and I had the builder add one...they basically changed the single toggle into a dual purpose switch, so what was the On/Off toggle is now an On/Standby/Off...so you always have to got through the standby stage when powering on or off...and it's great that they didn't have to drill holes to add separate standby...though only thing is, if I flip it too fast I can easily skip through the standby.

Anyway...the main/only reason I had them add the standby was for ease of use in a studio setting where I will often try out 2-3 guitars with the same amp when looking for tone, and I hated the fact that would need to turn down the volume on the amp when unplugging/plugging in the guitars to avoid the pop, since I would have a specific setting of the volume knob and I didn't want to disturb that. The only other option then was to turn the amp off when I swapped guitars...and that was a bigger PITA...so I had the amp builder add the standby.
Interesting side note...after my request and initial discussion of where to drill/add the separate standby, and them then suggesting that they replace the On/Off toggle with a three position and doing it that way...they then changed their amp build to include that exact same mod as a standard on their new amps as they realized my point about why a standby was really good to have...and it had nothing to do not damaging the amp by just going On/Off.
In fact when I first started to ask about the standby, they immediately said, "just turn down the volume to "0" when you power On/Off...but when I explained the studio scenario with multiple guitar swaps....they instantly realized the value and chose to make it a regular thing on all their new amps.

Oh by the way....the amp was a Savage Macht 12X 6V6 combo...an absolutely killer tone, built like tank, and one the best tube Tremolo circuits I've ever heard.

 

[Greg_L]

Turning the volume down and standby essentially does the same thing - it keeps signal from hitting cold tubes. If you probe your tube sockets on standby or with 0 volume, you'll get no readings in the signal path. Powering up in standby also keeps voltage spikes from hitting the tubes and all the little caps and screen/grid resistors. Ideally, in a fault situation, a fuse will blow before a mountain of voltage hits a fragile component. This is how my layman's mind understands it anyway. This is how it's been explained to me by an amp builder. The off/standby/on switch is a good idea. Orange does this and a lot of "boutique" amp guys do it too.

 

[miroslav]

Turning the volume down and standby essentially does the same thing - it keeps signal from hitting cold tubes.

Exactly.

 

[Greg_L]

Exactly.

You know, I'm wondering about the preamp section now though. I'm trying to remember if the preamp is "live" even in standby mode. I know the power section isn't, but what about the preamp? I don't think it is.

 

[bdenton]

Been decades since I messed with this stuff...maybe somebody else can flesh things out a bit...

On a tube musical instrument amp, "Standby" serves a couple (at least) of purposes...keep in mind that, unlike solid-state components, tubes have a finite, and relatively short, lifespan.

When turning your amp "on" for the day/gig/session, you should first turn it to "standby". This allows the tubes to gradually "come up" to operating temperature before you hit them with the "full power" line current...this will increase tube life.

As far as how long you should leave it on "standby", check the manufacturer's manual or website...if you can't find the info there, IIRC, back in the day it seems like we used to have them on "standby" for about 15 minutes before going to full power.

In a similar vein, if your amp sits in colder conditions (< 50-60 degrees) such as a van prior to a gig, it's a good idea to allow it to come to "room" temperature before going to "standby"...again, this will prolong tube life (and sometimes prevent a premature tube failure).

Another purpose of the "standby" switch is when you will not be playing it for a relatively short time, such as during a break in a gig or session. This allows the tubes to stay warm until you go back to full power...again, this lengthens tube life.

As far as "shut down" goes, there is no need to go to "standby"...just turn the amp completely off.

Hopefully, others can add to this...

 

[ocnor]

You know, I'm wondering about the preamp section now though. I'm trying to remember if the preamp is "live" even in standby mode. I know the power section isn't, but what about the preamp? I don't think it is.

The preamp section is live when in standby mode.

 

[miroslav]

Here's a whole lot more info on Standby swtches than anyone really wants to know......but it does reveal the origins and use...and it's appartently not to protect the tubes, assuming this guy really knows what he's talking about...and he sure seems to.

Of the three main uses mentioned...one being simply as a "mute" while amp is not in use, and for pluging/unpluging guitars without touching the volume....that is my personal use/need in the studio.

The Valve Wizard - Standby Switches

 

[Greg_L]

I don't trust anyone with that much of a hellbent bias towards a fucking switch. What a loon.

 

[miroslav]

Like I said...I don't know if he really knows...but he seems to know too much.

Anyway....if you're still building an amp, I see he has a whole lot of other info links about amp designs and whatnot on his home page...maybe there's something there of value....?

 

[Greg_L]

Like I said...I don't know if he really knows...but he seems to know too much.

Anyway....if you're still building an amp, I see he has a whole lot of other info links about amp designs and whatnot on his home page...maybe there's something there of value....?

Lol. No my amp will have standby switch just like amps always have. I'm okay with it. If it aint broke don't fix it.

 

[miroslav]

Well yeah...I like standby switches too.
I meant there seems to be a lot of other amp info on his home page...about all kinds of tube amp shit...I didn't look through it, but I see a lot of it has to do with amp designs and stuff.

Speaking of which...I just got The Tube Amp Book, written by Aspen Pittman, the original Groove Tubes guy.
Well I don't have it yet, it's on it's way, but it looks like it's full of great historical info and also it has a lot of schematics of classic amp designs and whatnot. Should be a nice read, if for nothing else but while in the John....

 

[Greg_L]

Well yeah...I like standby switches too.
I meant there seems to be a lot of other amp info on his home page...about all kinds of tube amp shit...I didn't look through it, but I see a lot of it has to do with amp designs and stuff.

Speaking of which...I just got The Tube Amp Book, written by Aspen Pittman, the original Groove Tubes guy.
Well I don't have it yet, it's on it's way, but it looks like it's full of great historical info and also it has a lot of schematics of classic amp designs and whatnot. Should be a nice read, if for nothing else but while in the John....

Yeah I read that book online. It's pretty good! For a n00b like me anyway.

For my own build, I'm just sticking with a straight stock standard early 70s 50w "Plexi" circuit. I don't wanna redesign anything. The most I'll do is maybe add an effects loop.

 

[rob aylestone]

The thing to remember is that tubes are not devices invented for guitarists! When they were providing amplification in all sorts of products, very few had the standby switch. The only reason music amps have them is so you can walk to the amp hit the switch and play. Amps without them meant you had to wait before the devices functioned. Service engineers of the day would simply hot swap valves (sorry, tubes) and pretty hefty powerful ones too. Tubes have a finite life, so running the HT supply through them physically wears them as the electrons gradually strip material from one location to the other inside. So you can cut the HT (not mains) from the tube, when you don't need it and save it's lifespan. Keeping the 6 volt heaters running means instant operation can be restored. All that happened is that the reason for the heater circuit has been forgotten, and people are naturally assuming heaters are essential. In pentode and tetrode designs the internal structure is pretty resistant to the physical movement of the grids when being used, so having the power supply applied suddenly without preparation, while being played does give them a little wobble but within the design spec.

Killing the HT silenced the device, and leaves it ready to start again instantly. That is it! In amp designs where the instant on isn't required, very few bothered with separate heater switches, you just had to wait until the tubes were warm enough to function. This included some quite high power tube designs back then. Somehow the idea of doom and gloom crept in, probably from one dying, and it's demise being linked to somebody who never used the standby. Just coincidence. The power to my guitar amp has been wired through my studios breaker for years, and I flick it off on my way out, and back on when I walk in, every day. Never even occurs to me to actually turn it off from the front panel!