Tube amp maintenance questions

[MartyGrass]

I'm back using a tube amp and want to care for it properly.

 

1. How long should I keep it on standby before powering it up? Does it even matter?

 

2. How long should I put it on standby before killing the power? Does that matter?

 

3. If I'm going to not use the amp for 15-30 minutes, is it better to turn it off, leave it on, or put it on standby?

 

4. How long after putting it on standby before the sound is stable or fully warmed up?

 

5. If the amp is transported in the trunk during winter, does the amp need to come to room temperature before powering it up?

 

Thanks.

 

[Billgelder]

I'm back using a tube amp and want to care for it properly.

 

1. How long should I keep it on standby before powering it up? Does it even matter?

 

2. How long should I put it on standby before killing the power? Does that matter?

 

3. If I'm going to not use the amp for 15-30 minutes, is it better to turn it off, leave it on, or put it on standby?

 

4. How long after putting it on standby before the sound is stable or fully warmed up?

 

5. If the amp is transported in the trunk during winter, does the amp need to come to room temperature before powering it up?

 

Thanks.

 

1. 1 minute, yes

2. 30 sec. yes or it might make a pop sound when turned off

3. I will shut it off if not used for over 10 minutes the tubes will last longer if turned off when not in uses.

4. see #1

5. We don't have winter in south Florida, but I will let the amp/tubes cool off before I move the amp. less damage to the tubes if cooled off before transporting.

[JeffB]

Well, I am a bad person and this post is just here to show you what you can get away with rather than what is the correct thing to do.

Probably dont do what I do.

I flick the power and standby switches on and off at the same time.

I leave the amp running for hours. Sometimes unattended for extended times. I just pull the guitar lead out a little bit at the amp input.

Ive done this for nearly 28yrs with one amp.

Ive put a full set of tubes in it three times over that period.(other than goofing around trying out different tubes) Not because I had to but because I thought I should.

About the only thing that Ive done "right" is to allow the amp to cool down for 5minutes before moving it.

 

I wouldnt do this to anyone else amp.

[Kuz]

I think the most important thing is letting the tubes warm up ( I wait 30-45 secs). I heard you can just turn the power switch off by itself with no waiting time required, but I turn the stand by off and wait about 10-15 secs to turn off the power switch. I use the standby when not playing more than a couple minutes, and then turn amp completely off if I am not going to be playing with in 15 mins.

 

I have never let the amp come to room temp before a gig, but with the pedal board, music stand, music, pics, input cords to plug in, ect the amp is probably close to room temp. I did make sure all the tubes are in all the way right before I turn it on before playing at a gig, because I have had the tubes rattle a little loose from bumps in the car.

[111518]

Standby activates the heating filaments in the tubes. There is some disagreement, I guess, about whether or not the warmup is necessary at all, but, the rule of thumb I picked up somewhere and have followed for 30 years is pretty close to Kuz's --15-30 seconds on standby, then power. I do have amps with no standby, and they take about 10-15 seconds to make sound once they are turned on; once they make sound, the electrons are flowing, and they are stable, at least in my experience.

 

I've always tended just to switch the power off, and leave the standby on, during breaks, but, that is probably stupid. No reason for the tubes to be heated all that time, so, would probably make more sense to turn them off, then repeat the standby/power sequence before the next set.

 

For powerdown, just flip both switches, maybe power a fraction ahead of standby. (No reason to keep heating the tubes.)

 

And, I've never waited for a cold amp to warm up, or a warm amp to cool down, although, as Kuz mentions, it tends to happen to a degree (pun?) during setup loadout. I don't ride tube amps around except to and from playing. Tubes can rattle loose, and, all combo amps tend to be top heavy and prone to fall over if you have to put then upright in a vehicle. They also slide around in the back of my truck, even on their back on a moving pad.

 

Again, all very unscientifically arrived at. I'd be interested in the advice of those who know better.

[Gitfiddler]

OK, assuming someone fails to follow all of these tube amp best practices recommendations, what's the worse (worst?) that will happen?

[peterbright]

The rules are meant to prolong the life of the tubes. Probably not overly important unless you really are using the amp/amps for hours a day nearly every day.

[Kuz]

OK, assuming someone fails to follow all of these tube amp best practices recommendations, what's the worse (worst?) that will happen?

 

It will shorten the power tube's life, as mentioned above.

[rockabilly69]

I turn the power switch on when I plug in the power cord, and then wait till everything else is setup to

turn on the standby switch. Soon as I'm done playing, I turn the standby switch off. When I'm ready to

slip the cover on my amp for loadout I turn the power switch off.

[bobmeyrick]

Standby activates the heating filaments in the tubes. There is some disagreement, I guess, about whether or not the warmup is necessary at all, but, the rule of thumb I picked up somewhere and have followed for 30 years is pretty close to Kuz's --15-30 seconds on standby, then power. I do have amps with no standby, and they take about 10-15 seconds to make sound once they are turned on; once they make sound, the electrons are flowing, and they are stable, at least in my experience.

 

I've always tended just to switch the power off, and leave the standby on, during breaks, but, that is probably stupid. No reason for the tubes to be heated all that time, so, would probably make more sense to turn them off, then repeat the standby/power sequence before the next set.

 

For powerdown, just flip both switches, maybe power a fraction ahead of standby. (No reason to keep heating the tubes.)

 

And, I've never waited for a cold amp to warm up, or a warm amp to cool down, although, as Kuz mentions, it tends to happen to a degree (pun?) during setup loadout. I don't ride tube amps around except to and from playing. Tubes can rattle loose, and, all combo amps tend to be top heavy and prone to fall over if you have to put then upright in a vehicle. They also slide around in the back of my truck, even on their back on a moving pad.

 

Again, all very unscientifically arrived at. I'd be interested in the advice of those who know better.

My understanding is that the power switch turns on the heaters and the standby applies the HT to the valves/tubes. Checking this, I came across this explanation of the function of the power and standby switches. The relevant bit is this -

 

"Standby switch: The standby switch usually allows the HT to be turned off while the heater and bias supplies are always on. Contrary to popular belief, the standby switch is not there to prolong valve life-span. The theory is that if the HT is applied while the cathodes are cold they will be 'stripped' by ions crashing into the unprotected cathode. However, this simply does not happen. It is an urban myth borrowed from transmitter and cathode-ray tube technology NOT ordinary 'receiving' valves. The only valve which might ever be at risk of failure is a rectifier valve, because it has to supply inrush current to the reservoir capacitor, and some guitar amps fail to use enough limiting resistance to protect against this (see more on rectifies).

On the other hand, leaving a cathode hot without any anode current flowing does lead to the very real effect of cathode poisoning, which reduces the gain (transconductance) of valves. Fortunately this phenomenon really only becomes significant if the valves are left on standby for hours on end.

If you're wondering why all those old amps use a standby switch, its because Fender was designing complicated amps on the cheap. In the bigger versions of the Bassman, money was saved by using power supply caps that were rated only for the working voltage, not the peak voltage which occurred before that valves start drawing current. As everyone knows, Marshall simply copied the Bassman without a second thought, complete with standby switch, so now we have the two biggest names in the industry using standby switches, and the rest is history. The other big players, Vox and Gibson, never used standby switches since they didn't need them. Only very recently have they started adding them, purely because too many guitarists want their amp to look just like a Fender/Marshall, even though nowadays no designer (who values his reputation) uses underrated capacitors. But the average amp tech doesn't know this.

Note that even the RCA Transmitting Tubes Technical Manual No. 4, p65, states: “Voltage should not be applied to the plates or anodes of vacuum, mercury-vapor, or inert-gas rectifier tubes (except receiving types) until the filaments or cathodes have reached normal operating temperature.” [My italics]. In a properly designed amp, a standby switch is nothing more than an expensive, oversized mute switch."

[JeffB]

My understanding is that the power switch turns on the heaters and the standby applies the HT to the valves/tubes. Checking this, I came across this explanation of the function of the power and standby switches. The relevant bit is this -

 

"Standby switch: The standby switch usually allows the HT to be turned off while the heater and bias supplies are always on. Contrary to popular belief, the standby switch is not there to prolong valve life-span. The theory is that if the HT is applied while the cathodes are cold they will be 'stripped' by ions crashing into the unprotected cathode. However, this simply does not happen. It is an urban myth borrowed from transmitter and cathode-ray tube technology NOT ordinary 'receiving' valves. The only valve which might ever be at risk of failure is a rectifier valve, because it has to supply inrush current to the reservoir capacitor, and some guitar amps fail to use enough limiting resistance to protect against this (see more on rectifies).

On the other hand, leaving a cathode hot without any anode current flowing does lead to the very real effect of cathode poisoning, which reduces the gain (transconductance) of valves. Fortunately this phenomenon really only becomes significant if the valves are left on standby for hours on end.

If you're wondering why all those old amps use a standby switch, its because Fender was designing complicated amps on the cheap. In the bigger versions of the Bassman, money was saved by using power supply caps that were rated only for the working voltage, not the peak voltage which occurred before that valves start drawing current. As everyone knows, Marshall simply copied the Bassman without a second thought, complete with standby switch, so now we have the two biggest names in the industry using standby switches, and the rest is history. The other big players, Vox and Gibson, never used standby switches since they didn't need them. Only very recently have they started adding them, purely because too many guitarists want their amp to look just like a Fender/Marshall, even though nowadays no designer (who values his reputation) uses underrated capacitors. But the average amp tech doesn't know this.

Note that even the RCA Transmitting Tubes Technical Manual No. 4, p65, states: “Voltage should not be applied to the plates or anodes of vacuum, mercury-vapor, or inert-gas rectifier tubes (except receiving types) until the filaments or cathodes have reached normal operating temperature.” [My italics]. In a properly designed amp, a standby switch is nothing more than an expensive, oversized mute switch."

Well if this is true, and it must be, its on the internet, it explains why after years of treating the two switches as one Ive never had a problem.

Silly internet. Its so conflicted. .

I have to admit, about 20yrs ago a tech did tell me that the standby wasnt important. I was never sure if he was correct or a heretic. I was already pretty committed to using the two switches as one by habit anyway.

[111518]

...sorry. Bobmeyrick is correct. I switched (another pun?) the names of the switches, I guess because when "power" is on but not "standby" the amp seems to me to be standing by. (Although I do understand that "power" sends AC to the power transformer.) And, on fenders, the switches were always in the back so, who read the labels? Obviously, the power light comes on when the power switch is thrown, and absolutely nothing happens when you throw standby before power, so the sequence I described wouldn't make any sense in real operation.

 

If you reverse the names of the switiches, however, my post is not that far off from the logic of Bobmeyrick's post, so,. I guess in actual fact I haven't been too far off in understanding the system. I have heard that the only tube that benefits from "preheating" is the rectifier tube, which not all amps have at all.

[Guest HRB853370]

Don't do what I do. I just unplug the amp from the wall when done playing. Saves the switch from wearing out but makes a helluva spark at the wall plate!

[MartyGrass]

This is all horrifying stuff. It reinforces the basic view I have that about half of what we do in life is either unnecessary or wrong.

 

I learned how to deal with Fender amps from an old timer who repaired tube TVs for a living. (He was also definitely tied to the mafia, too, but that's another story.) He didn't use the standby switch. It was power on or off- period. When you were not using the amp for a few minutes, turn it off if you want to save a little electricity.

 

In his world of high end tube TVs, there were no standby switches. Magnavox, RCA, GE, etc. would have put them in if they were helpful. The TVs were left on all day at the shop, 9 AM to 9 PM. And the tubes lasted a very long time.

 

I have heard all of the suggestions over the years about the proper use of standby switches and that it is important not to power up a frigid tube.

[garyyamane]

Here is an article that Henry of Red Plate amps recommends.

 

http://www.peavey.com/monitor/pvpapers/Chapter6.pdf

[JeffB]

This is all horrifying stuff. It reinforces the basic view I have that about half of what we do in life is either unnecessary or wrong.

 

I learned how to deal with Fender amps from an old timer who repaired tube TVs for a living. (He was also definitely tied to the mafia, too, but that's another story.) He didn't use the standby switch. It was power on or off- period. When you were not using the amp for a few minutes, turn it off if you want to save a little electricity.

 

In his world of high end tube TVs, there were no standby switches. Magnavox, RCA, GE, etc. would have put them in if they were helpful. The TVs were left on all day at the shop, 9 AM to 9 PM. And the tubes lasted a very long time.

 

I have heard all of the suggestions over the years about the proper use of standby switches and that it is important not to power up a frigid tube.

Anything to do with valve amps and stomps is a mine field of opinion and second hand info.

Speak to your local tech. Generally they laugh about stuff we go nuts about.

[yoslate]

OK, assuming someone fails to follow all of these tube amp best practices recommendations, what's the worse (worst?) that will happen?

 

You'll be just a little more like Jeff.... ; )

[MartyGrass]

Anything to do with valve amps and stomps is a mine field of opinion and second hand info.

Speak to your local tech. Generally they laugh about stuff we go nuts about.

 

One thing I've always been grateful for is being around those who have built guitars and electronics for a living for many decades. Most of them are salt of the earth pragmatists, not academicians, theorists or snobs.

 

When one of them laughs at something, I still get a second opinion and explanation. Sometimes I find that the second opinion includes that the first opinion is stupid.

 

So there are some general principles that cover the field.

 

1. Not everybody can be right.

 

2. Not everybody can be wrong.

 

3. No one is exclusively one or the other all of the time.

 

4. When there is a vacuum of facts, opinion fills the void.

 

5. Facts speak for themselves. Opinions need a voice behind them, the weaker the basis the louder the volume.

 

6. Inertia, momentum, dogma and tradition always have the advantage.

 

7. The louder the disagreement, the less important the matter is.

[smurph1]

My Princeton doesn't have a standby switch.. So I usually Let the tubes cool a bit, and then turn the volume down before I pull the guitar cord out.. Seems to work ok.. Any opinions?

[111518]

garyyamane, on 30 Dec 20 Sorry, don't know what happened. I'm in a box and can't get out ....

 

[JeffB]

 

One thing I've always been grateful for is being around those who have built guitars and electronics for a living for many decades. Most of them are salt of the earth pragmatists, not academicians, theorists or snobs.

 

When one of them laughs at something, I still get a second opinion and explanation. Sometimes I find that the second opinion includes that the first opinion is stupid.

 

So there are some general principles that cover the field.

 

1. Not everybody can be right.

 

2. Not everybody can be wrong.

 

3. No one is exclusively one or the other all of the time.

 

4. When there is a vacuum of facts, opinion fills the void.

 

5. Facts speak for themselves. Opinions need a voice behind them, the weaker the basis the louder the volume.

 

6. Inertia, momentum, dogma and tradition always have the advantage.

 

7. The louder the disagreement, the less important the matter is.

Should make this a sticky..

 

What the hells a sticky? Is there another name for it?

 

Should be pinned somewhere.

[bobmeyrick]

To summarise the above comments, it would seem that if the amp has a standby switch, you switch on the power and wait for a minute or so to let the tubes warm up before switching on the standby. To avoid "cathode poisoning" don't leave the amp switched on but with standby off for more than 15 minutes or so. Above all, don't panic!

[JeffB]

 

You'll be just a little more like Jeff.... ; )

I thought about that for a bit. Scary thought.

[bolero]

well if the amp has a rectifier tube then you don't need to use the standby switch when you power it up...the tube rectifier softens the current rush to the power tubes and warms them up slowly enough

 

whenever I power UP I use the standby switch, if the amp has one. Usually 10 seconds is enough, although I don't *crank* the amp for at least another minute

 

when you turn OFF the amp, you don't need to use the standby switch... it will also drain the filter capacitors & make the amp safer for poking around in. If you do use the standby to power down, the filter caps will retain a high voltage charge. which isn't good or bad for the amp. so powering down doesn't matter

 

someone I respect told me that what wears out tubes is the heating/cooling cycles....so he said it's best not to use the standby switch if you're taking <30 min break, just leave the amp on & it will be fine

[Gitfiddler]

Another question: Why do some small amps (e.g. Champs, Princetons, Blues Jr., etc) NOT have a Standby Switch?