Tube amps without standby switches

Discussion in 'Amps and Cabs' started by MartinC, Feb 7, 2008.


  1. MartinC

    MartinC Member

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    What's the story here?

    Do such amps have other means of protecting tubes during start up? Or do they simply wear tubes out faster?

    Once they're fired up, is the idea to simply turn the volume down (guitar or amp) when they're not being played for a while instead?

    Are they to be avoided?

    I've got one at the moment (Classic 30) and I can't say it's ever bothered me. I'm also considering a new amp that doesn't have a standby either ... is it something that would put you off? Even if you liked everything else about the amp?
     
  2. rhythmeister

    rhythmeister Member

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    One part of the story is that if the amp is tube rectified (as opposed to ss rectified) then standby is superfluous b/c the rectifier tube fulfils the same role a standby switch would.

    Cheers,
    Blair
     
  3. Blue Strat

    Blue Strat Member

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    ...but ONLY if the particular rectifier is "indirectly heated" which results in slow turn on. The only common guitar amp rectifiers that do this are 5AR4/GZ34, 5V4, and some special 5Y3s. The others turn on quickly and slam the other tubes just as a SS rectifier does.
     
  4. MartinC

    MartinC Member

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    Anyone else? ...
     
  5. somedude

    somedude Member

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    Turn the gain down to zero. Problem solved.
     
  6. fullerplast

    fullerplast Senior Member

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    Choose an amp based on tone, not standby switches!

    If you eliminate those without, you could be missing out on some of the greatest amps ever made....like tweed deluxes, BFPR's, or AC30's!
     
  7. MartinC

    MartinC Member

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    Agreed. As I said I have an amp (C30) without standby now and it has never bothered me ... but I've read a couple of posts hear and there about this amp from people saying that it needs a standby, and even a mod to add a standby. I'm just checking to see if I've missed something. Definitely tone comes first.

    Thanks
     
  8. hasserl

    hasserl Member

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    Standby switches, IMO, are greatly overrated for guitar amp use (meaning their value is greatly overrated, not the quality or specification of the parts used ;) ). They are handy for silencing an amp for switching guitars, etc. but for extending tube life there is no evidence they provide any benefit. If they make you feel better, that may be a side benefit. Certainly nothing to worry about, or waste time and resources adding one to an amp designed without one. JMO of course.
     
  9. HKGuns

    HKGuns Member

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    Excuse me, could someone 'splain to me how turning the gain down replaces a standby switch? - I don't think so.

    No evidence they provide any benefit? You don't think all that heat at idle has any effect on your tubes or it's circuits?

    They're there for good reason.. Slamming cold tubes has never been and never will be a good idea.

    They certainly aren't the tube equivalent of a mute button.
     
  10. hasserl

    hasserl Member

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    What I, or anyone else, thinks is not evidence, it is opinion. Show proof that "slamming" cold tubes has any harmful effect. Explain why slamming cold tubes is less harmful than slamming hot tubes, or is less harmful than slamming standby switch contacts, or less harmful than slamming filter capacitors.
     
  11. somedude

    somedude Member

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    Turning down the gain prevents you from hitting cold tubes with signal.
     
  12. MartinC

    MartinC Member

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    At this point I think we need an amp builder guru to chime in and explain the facts ... anyone?

    I do know, for a fact, that amp makers' manuals for amps with standbys state that the standby mode should be used when powering up to prolong tube life:

    From the Mesa Boogie Express manual:

    STANDBY: Perfect for set breaks...this toggle switch also serves an even more important purpose. In the STANDBY position (switchup), the tubes are at idle so that during power up they may warm up before being put to use.

    Before the power is switched on, make sure the STANDBY switch is in the STANDBY position. Wait at least 30 seconds and then flip the STANDBY switch to its ON position. Following this simple warm up procedure helps in preventing tube problems and increase their toneful life substantially.
    From the Genz Benz Black Pearl Manual:

    STANDBY SWITCH: The Standby switch removes the high voltage power supply from the plate circuit of the output tubes to protect the tubes from “cathode stripping” when first powering up the amplifier. The recommended start-up procedure is to place the standby switch to the standby position, turn on the power switch and allow the amplifier to warm up for at least 30 seconds before switching the standby switch to the operate position. This will help to prolong the life of your output tubes.​

    and I'll ask again from my original post: Do amps without standby switches have other means of protecting tubes during start up? Or do they simply wear tubes out faster?
     
  13. blackba

    blackba Supporting Member

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    Amps like a fender champ have no standby switch, but I heard since they are class A, that they don't need one, not sure why or if this is correct.

    A vintage vox AC50 has not standby switch and uses a Brimistor to help with the cold start, not sure what this device actually does.

    Whether your amp has a standby switch or not, its a good idea to let it warm up before slamming it with your favorite boutique overdrive.
     
  14. hasserl

    hasserl Member

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    Martin, titles mean nothing. Anybody can build amps, doesn't make them a guru. Pay attention to facts, not opinions. Mesa Boogie and Genz Benz are simply repeating the same urban myths they've heard themselves.

    Search out the info yourself, there is NO empirical evidence of cathode stripping in guitar amps. NONE, ZILCH, NADA. Anyone that says otherwise, ask them to provide it, they will not be able to, it doesn't exist.
     
  15. MartinC

    MartinC Member

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    I probably used the wrong terms ... by "amp builder guru" I meant someone who knows how tubes work and can explain whether cathode stripping (or other damage) is possible and detrimental in a guitar amp, under start up conditions.

    I'm on the fence ... on the one hand the only evidence that I have now is that manufacturers go to the trouble of fitting standby switches to most tube amps, and then tell you to use it at start up ... why would they do that if there was no benefit? Then on the other hand there are tube amps with no standby switches that work perfectly well ... but I don't know if they have other tube protection mechanisms, other than the mysterious Brimistor on an old AC50.

    Just curious at this point I suppose.
     
  16. Jon Silberman

    Jon Silberman 10Q Jerry & Dickey Gold Supporting Member

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    hasserl is far from alone in his views and the fact that a major tube manufacturer from decades back might have disagreed with him does not make him wrong.

     
  17. MartinC

    MartinC Member

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    Jon, thanks a million ... I think that's exactly what I was looking for. Even though David B. Lamkins is a software engineer (if he's the same guy I just found on the web) he sounds like he's done his homework and I like the way he thinks.

    I shall continue along with my non-standby amp ... and will take this feature off the checklist when buying in the future ... not that it was ever there before really, until yesterday when I was comparing two possibles and noticed one had standby and the other didn't (same manufacturer by the way ... and same range ... Hughes and Kettner Statesman). That's, in fact, what prompted my opening post.

    If I do end up with an amp with a standby switch, I think I'll use it at start up ... for 15 seconds :AOK
     
  18. hasserl

    hasserl Member

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    Thanks John, good info that should help Martin & others looking for truth.

    Hogy, insults and personal attacks are the easy way out. If you have evidence of cathode stripping in a guitar amp go ahead an post it.
     
  19. somedude

    somedude Member

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    Rivera recommends dropping the gain to zero for 30 seconds. It lets the tubes warm up with very little signal passing through them.

    FWIW.... since no one seems to want to believe me on the gain knob thing.
     
  20. MartinC

    MartinC Member

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    Not a case of disbelieving you on my account ... in the end I was looking more for whether damage does actually get done ... is there a sypmtom to treat, rather than what's the treatment. Admittedly that's not how I phrased it in my original post ... I was just throwing the subject out there at first.

    Thanks for posting!;)
     

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