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Tube amps - powering on in "Standby" mode

Discussion in 'Amps and Cabs [BG]' started by Skel, Apr 15, 2006.


  1. Skel

    Skel

    Jun 19, 2005
    Boulder, Colorado
    Just wondering if any of you tube amp users are impatient like me, and don't really power the amp up in standby mode, waiting for a minute or two, then switching the amp out of standby. Is it really that hard on the tubes to simply power the amp up and wait until you hear the amplification? Also, if this is hard on the tubes, is it just the power tubes, or the preamp tubes as well? I've noticed on my SVT-3 PRO, which doesn't have a "standby", that it takes about 30 seconds after powering the amp up before it kicks on. It's as if there is some kind of protection going on, maybe waiting for the tubes to warm up?
     
  2. In the SVT-3 Pro (I have one) The manual says that in the warm-up stage... a small current is going to the tubes to get them preped for the massive onslaught of voltage that is coming.

    Something like that... it's in the manual.

    For the first part... if you're talking about an all tube head. I've head that in the long run, it will damage the tubes if you don't wait.
     
  3. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    It only takes about a minute or two in standby mode for tubes to warm up. If you don't wait, it will cause the tubes to lose life a tad faster, but it really does not matter that much. There are tube amps that do not have standby.
     
  4. I'll just bet this has been discussed before. Try the search function.
     
  5. Skel

    Skel

    Jun 19, 2005
    Boulder, Colorado
    I think you're right, given that some amps don't have the standby switch - of course the ones I've seen without one have been pretty low wattage.
     
  6. i just bought a orange ad200b and it only takes MAYBE 30 seconds to warm up the tubs and i'm ready to go. I'm sure that its not going to kill the tubes or the head to just turn it all on at once of off at once, but if your going to wait the 30 seconds or minute or whatever, why not just leave it on stand by and "be safe."
     
  7. Skel

    Skel

    Jun 19, 2005
    Boulder, Colorado
    You know, I always come back to this argument too. It's just smarter to wait 30 seconds...I don't always do it, but I try to whenever I can. I try to turn the amp on and think of something I need to do, like tune, put the strap on my bass, even clean my bass, etc. so I don't notice the time.
     
  8. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    So you're thinking maybe the engineer didn't have anything to do that day and decided, what the hell, think I'll raise the cost of this amp a few bucks and add a stand-by switch ?

    Seriously, the switch was put there for a reason. Maybe you should use it ?
     
  9. Amps that don't havea standby switch (which are all valve) have a warm up stage; ie, you won't hear anything until the valves have warmed up. The Peavey classic guitar amp is an example, albeit a low-wattage amp.

    but yes, i'd use the switch if you have one, and yes, this has been discussed brutally. =)
     
  10. I've been playing tube amps for over 50 years. If it has a standby switch I hit the standby switch, then the power switch, put on the guitar, make a final check of the stage to make sure I don't trip and fall on my butt, and then light the amp. The whole process takes somewhere between a 30 seconds and a minute. If the amp doesn't have a standby switch, I go through the same process and it still takes 30 seconds to a minute. If it is a SS amp, I do the same and it still takes at least 30 seconds. You don't have to wait an exceedingly long time for tubes to warm up.
     
  11. this has also been debated in other threads... most say that 30 seconds is enough.

    i want my Trace....
     
  12. savit260

    savit260

    Mar 6, 2006
    Boston
    You seem to have the power up order backwards here. I'm sure this is just an typo or something. Power switch goes first to warm up the tubes. Thirty to 45 seconds should be plenty. Then the standby switch goes to the on position, and your good to go.
     
  13. OOOps. I guess I need to take the brain off standby. It was a long night.
     
  14. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    The standby switch isn't a necessity, and is seldom seen on other than MI amps. The main purpose is so you can shut down the B+ voltage during a break and not have to warm up the heaters when you're ready to play again. You don't have to preheat the tubes on start-up.
     
  15. teleharmonium

    teleharmonium

    Dec 2, 2003
    Most of my tube amps that I use for bass are tube rectified. Two of them are SS rectified and have standby switches, so I power on the amp in standby mode and then flip the standby switch after a minute or so. Then, if I have the time, I let the amp run with the volume down for at least 15 minutes or so, while I set up my mic and the PA if needed, get a beverage, and tune up my bass and put it on the stand.

    If there's a break in the set, I just turn the volume down on the amp, I don't go into standby mode.

    At the end of the set, I put the amp into standby again, wait ten seconds or so, and then power off. This way, the amp is on standby for next time, and I avoid sending a loud pop to the speakers, which happens sometimes, particularly on one of the amps (they're both the same basic amp, but with different front panels; Jennings/Vamp/Triumph 100 watt heads).

    I see no reason not to do any of these steps. I use good tubes, but a sudden onslaught of 350v or so to the plates just seems like a bad idea. I think that an old resistor or something in the bias or high voltage circuit might take that as a cue to go ahead and fail. Now if they had a slow rise on the plate voltage as a design feature, maybe I wouldn't worry about it, but my amps don't.
     
  16. Skel

    Skel

    Jun 19, 2005
    Boulder, Colorado
    Thanks Bill. This makes sense.
     
  17. I could be wrong but doesnt turning it straight on cause cathod stripping?
     
  18. ibz

    ibz

    Apr 14, 2005
    Columbus, OH
    Correction:

    Read my later post on the second page, I got some info mixed up from bad sources. I hope I didn't help in keeping that misinformation floating around.
     
  19. the classic 50's and 100's have standby switchs, i always put that down to them being higher models, the classic 30 doesnt and i didnt think it was a Class A amp, but, oh well, learn something new every day :) , i love my classic 30 (i think the classic 30 amp head has a standby switch tho?)
     
  20. I've already weighed in elsewhere, but since there seems to be a conflagration of "experts" on this issue, i'll add my thoughts, too.

    You don't see high powered tube amps anywhere BUT MI anymore. Most esoteric hifi stuff has tube rectifers which function as their own startup delay so no standby would be needed, but if you're talking an SVT running 700+ volts on its output tubes, letting the cathode warm to emission BEFORE you start blasting electrons off of it is a good idea. Even in the 360KW tube transmitter at work with directly heated cathodes (heater and cathode are the same element) there is a standby AND a back heat mode. ..might be a REASON for that. :meh:
     

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