# Stand by switches. More harm than good?



## traynor_garnet (Feb 22, 2006)

This is an interesting read: http://www.londonpower.com/standby-switch

He concludes they are useless and shouldn't be used. The only time I have had troubles with blowing fuses is when using standby switches in vintage amps. I have been told modern tube rectifiers cannot handle the crushing juice.

TG


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## jb welder (Sep 14, 2010)

They're not really useless, just Kevin thinks so :smile-new:.
Ask people who gig with them, they don't _want_ to turn off the volume between sets. They want to use the standby. So they do serve a purpose, as a mute switch. On some amps, the standby _is_ actually just a mute switch.
It is true they should not be used with tube rectifiers as they put unneeded extra stress on the rectifier tube.


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## traynor_garnet (Feb 22, 2006)

Thanks for responding. With a tube rectifier, is everything powering up slowly anyway making a stand by kind of irrelevant? At any rate, I may stop using mine given the lack of well produced modern rectifier tubes.

TG



jb welder said:


> They're not really useless, just Kevin thinks so :smile-new:.
> Ask people who gig with them, they don't _want_ to turn off the volume between sets. They want to use the standby. So they do serve a purpose, as a mute switch. On some amps, the standby _is_ actually just a mute switch.
> It is true they should not be used with tube rectifiers as they put unneeded extra stress on the rectifier tube.


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## jb welder (Sep 14, 2010)

traynor_garnet said:


> With a tube rectifier, is everything powering up slowly anyway making a stand by kind of irrelevant


Yes, it serves no function at warm-up. And once it is warmed up, if it is used it will only add stress to the rectifier tube, so good idea to not use it at all (for amps with tube rectifier).


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## traynor_garnet (Feb 22, 2006)

Thanks again for the response. This seems to be a two person thread and I am a bit surprised. Is this common knowledge that I have simply been blind to?

If so, sorry for producing "the stand by switch of threads" LOL


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## greco (Jul 15, 2007)

I am reading this with interest ...as number 3 person.

I'll bet many/most swear by the use of stand by switches. Given my "bet", I am also very surprised that others have not been commenting vehemently.

Thanks for starting the thread!

Cheers

Dave


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## ed2000 (Feb 16, 2007)

How about the Fender Vibrochamp...all tubes - no standby?

So, when I power up my '65 Traynor Bass Master that had the factory conversion to SS rectifier -standby or sitdown?

Reminds me of the old aircraft radial engines that were cranked to build up oil pressure and then the ignition was turned on.


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## GTmaker (Apr 24, 2006)

first of all I have to say that I have no clue about the use or non-use of a standby switch .
Does it really add stress to the rectifier tube....?

If it did, you would think that there would be plenty of testimonials in the last few decades
that would vilify that dammed standby switch because it ruined a perfectly good rectifier tube....

I haven't seen any such testimonials from amp owners...I know that doesn't prove much but it says something to me at least.

G.


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## Electraglide (Jan 24, 2010)

I figure there was a reason they were put on older tube amps so I use them on the amps that have them.


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## WCGill (Mar 27, 2009)

GTmaker said:


> first of all I have to say that I have no clue about the use or non-use of a standby switch .
> Does it really add stress to the rectifier tube....?
> 
> If it did, you would think that there would be plenty of testimonials in the last few decades
> ...


Depending on the rectifier tube, the way the filter caps are positioned in the circuit and the way the owner uses the switch, it can create a "perfect storm" and take out the rectifier tube, the modern production being not as robust as NOS and unable to stand the abuse. Of course the average owner wouldn't know these things and just assumes that the tube failed randomly.


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## GTmaker (Apr 24, 2006)

WCGill said:


> Depending on the rectifier tube, the way the filter caps are positioned in the circuit and the way the owner uses the switch, it can create a "perfect storm" and take out the rectifier tube, the modern production being not as robust as NOS and unable to stand the abuse. Of course the average owner wouldn't know these things and just assume that the tube failed randomly.


 the reply above is a perfectly reasonable response.
What I don't understand is all the manufactures to this day still using/adding the standby switch.

On an amp with a tube rectifier, does the standby switch offer any useful purpose.?
When I walk away from my amp for half an hour and leave it on standby, am I in any way offering some 
(re leaf/rest/not on full power) to my tubes?

G.


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## bluzfish (Mar 12, 2011)

I've always wondered that myself. Don't tubes basically draw minimal current when idle and only draw current when an input signal requires them to? If so, wouldn't an input mute switch would perform the same function without messing with the rest of the amp circuitry? I suppose spring reverb bumps or electrical spikes would still get through, but how often does that happen?


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## High/Deaf (Aug 19, 2009)

They draw minimal current for push-pull class AB amps. For class A amps, the tubes are always running significant current, even in idle. I think standby switches can be useful for that. I notice my LSS is cooler when in standby. Funny enough, it's also somewhat infamous for blowing rectifier tubes, but I've never had a problem with mine.

Muting is accomplished with pedal tuners most of the time now (if you have them configured to do that). Honestly, I sometimes think the standby switch is to show everyone you have a tube amp. Transistor amps lack that visual cue.


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## jb welder (Sep 14, 2010)

GTmakers question about why standby switches ruining rectifier tubes is not a historical problem is a very valid question.
Agree with WCGill's response that modern production rectifier tubes are not up to the task, and also that a user may not realize that their rectifier tube failed prematurely, or what caused it.

I think a great solution is the weber copper cap, costs about the same as a tube, you won't be able to tell the difference sound wise, and it doesn't wear out. Stand-by switching won't hurt it.


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## High/Deaf (Aug 19, 2009)

The one tiny difference may be the copper cap will be stiffer than the tube. The voltage from the tube will sag more than from the ss device when worked hard. 

Now whether you can hear that voltage sag is debatable. I think you can. But is that because I want to hear the difference or because I can hear the difference? Things that make me go: hmmmmm.

Whether you hear the difference or not, I think those copper caps are a great backup. A blown tube rectifier can prematurely end an evening with no backup (been there, got no t-shirt, just embarrassment).


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## TheYanChamp (Mar 6, 2009)

I second the copper cap as a spare. My Ad-30 seems to go through one Rec tube a year, almost like clockwork. 


So, stop using the standby switch you say? Hmm. Gonna have to sleep on that. Aren't you just slamming the cold tubes with high voltages?


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## High/Deaf (Aug 19, 2009)

I think with a tube rectifier, HV comes up slowly as the tube warms up. So no standby required there.

With an ss rectifier, the HV comes up immediately so a standy is a good idea there.


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## jb welder (Sep 14, 2010)

High/Deaf said:


> The one tiny difference may be the copper cap will be stiffer than the tube. The voltage from the tube will sag more than from the ss device when worked hard.


The copper cap has built in sag circuitry. That is why it is much preferred over simple ss replacement modules. There may be some very slight differences in the subtleties of the characteristics of the sag (compared to actual tube), but no one seems to be able to notice in AB testing.


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