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PV Classic 30 & It's Lack Of Standby

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Electric I, Sep 29, 2006.

  1. Electric I

    Electric I Member

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    Played one for the first time yesterday & really took to it. I'd like to pull the trigger, but it's lack of standby & induced loud snap/crackle/pop on power-down has me concerned.

    Will this feature, or lack thereof, cause serious problems over time ? Like this 'cathode stripping' I've heard/read about?

    Also, is it safe to pull 2 power tubes to reduce wattage ?

    The extension speaker out requires a 16 ohm cab/speaker, correct ?
     
  2. Blue Strat

    Blue Strat Member

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    This is the EL84 amp, correct? More often than not, EL84 amps are "cathode biased" and share cathode resistors. This means that if you pull 2 (of the 4) power tubes, the remaining tubes will run EXTREMELY HOT and, ultimately, self destruct.
     
  3. Chris Scott

    Chris Scott Silver Supporting Member

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    Leave it to Peavey to make a great sounding tube amp that your tax return from workin' at Mickey-D can cover...

    Don't worry about the lack of stdby switch-- Hartley knows what he's doin', and for God's sake man-- Don't yank the output tubes, unless meltdown is something you need in your life. Get a Mass or equiv.
     
  4. Guinness Lad

    Guinness Lad Silver Supporting Member

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    I think there is a device called a thermistor which has to heat up before the power tubes can see voltage. Whatever this component is it should protect the tubes...not sure if Peavey uses it. EL-84's are cheap and by the time the cathode material would/could strip off the tubes they would be sonically shot anyway. I wouldn't worry about it and just replace the tubes when they loose their sparkle which should be about every 6 to 12 months depending on how much you play.

    The popping on shutdown is probably due to one of the pre-amp tubes. I have experienced this as well and what I do is put another tube into the tube slot (s) until I find the one that makes the amp pop. I don't think it's a problem with the amp or the tube just how the two components interact. I think some tubes are slightly hotter (more output) and this causes the circuit to make the popping noise you are decribing.
     
  5. Miles

    Miles Member

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    Just don't pull the tubes

    The popping sound occurs with just about any peavey C30 I've messed around with when you shut it down. The same happens if you shut any amp w/ a standby switch completely off without putting it on standby first. The power tubes can take a little bit more of a beating for this, but it's not something to fret about.
     
  6. donnyjaguar

    donnyjaguar Member

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    Yes, I've seen many EL84/7189/6BQ5 tube amps with no standby. Peavey amps seem to be built to a (lower) price. Will adding a standby switch help with cathode stripping? Of course it will. If you like the amp, go for it. If it were me, and I could get it for a good price (one locally for sale for 400$Cdn, but I don't consider this a good price) I'd put the standby switch in there just for convenience. Sometimes its a simple matter of replacing the power switch with a 3 position toggle so centre is off, one way is Idle and the third Run.
     
  7. rockon1

    rockon1 Member

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    Its not cathode biased. HOWEVER the heaters are wired in series so if you pull one out they all go out. So you cant pull two tubes. HOWEVER I saw a clever mod where you clip the tube pins and leave the heater pins and bingo -half power! Bit much trouble for the reduction but doable.Heres the thread


    http://forums.peavey.com/default.asp?action=9&read=80975&fid=11#349181
     
  8. Electric I

    Electric I Member

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    Why yes it is


    Duly noted. Think I'll leave well enough alone. Thanks for the input.
     
  9. Electric I

    Electric I Member

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    I take it the thermistor is somewhat of an automatic switch. Makes sense.

    All I know is it's almost painful to hear & I'll definitely be looking into a mod to install a standby switch. Thanks.
     
  10. Electric I

    Electric I Member

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    Cool beans. Thanks a ton for the link.

    And thanks to all for the insight.
     
  11. Miles

    Miles Member

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    Besides, if anything, the tubes get more wear and tear from rattling around so much in the combo. While this is partially true for most combo amps, it's especially true in amps such as the C30 or some lower grade fenders. They can really take a beating, and at that point, the lack of a standby switch is hardly noteworthy.
     
  12. LOCUSTFIST

    LOCUSTFIST Member

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    two speaker outs?...one 8ohm and one 16ohm.

    on the 50 they both become 8 ohm when you use them both...if there is one believe it to be 16
     
  13. hasserl

    hasserl Member

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    There is no thermister in the amp, but don't worry about it. Cathode stripping is an over hyped scare story on the internet, one of those urban legend things. Somebody says it once and it gets picked up and repeated often enough people think it's true. Cathode stripping is something that effects transmitters running much higher voltages than our guitar amps. Your tubes will wear out from playing, or as someone else noted, from rattling around while you haul it from place to place long before the cathodes strip. Or the filaments will give out first. Just don't worry about it. plug it in, let it warm up and play it. When you're done turn it off. It's simple, and needn't be any more complicated.
     
  14. Leftee

    Leftee Guest

    +1 on all that. Cathode stripping is way over-quoted and applied in the audio/guitar world.

    RE: C30 pop/bang on shut-down. Turn the reverb down before shutting it off. Should knock that noise down quite a bit. It's a common thing with the C30. No big deal. They're great and reliable amps.
     
  15. Leftee

    Leftee Guest

    FWIW I have a worked/owned, etc. a number of OLD tube amps. I have one right now and it doesn't have a standby feature. Its 50+ year old tubes still sound fine.
     
  16. BBQLS1

    BBQLS1 Member

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    That's weird it doesn't have standby. I had a classic 50 with standby and it never poped when turning it off.

    I wonder if a better switch would fix the problem?
     
  17. Leftee

    Leftee Guest

    Or he could turn the reverb down before shutting off...

    ... really...

    That works on the C30.
     
  18. vibroverbus

    vibroverbus Member

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    For older amps w tube rectifier it will provide a 'soft start' as it won't provide DC until it heats up, which is another reason old amps are easier on tubes. Of course the rectifier tube isn't getting a 'soft start' so it would be cathode stripping if one was fanatical about it...

    Agreed that it's not as big a deal as some people might freak out about - most 'regular' players have never heard of this and most rock-blues-etc players will do much more 'damage' (wear) by playing at heavy clipping levels - that's why tubes are replaceable, right? Still I always start-up with standby on and shutdown with it off - why not treat the gear as well as you can if you have the option?
     
  19. Electric I

    Electric I Member

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    Reverb is always off. In fact, I never use it on any amps & sometimes I even pull the tank altogether.

    Actually, I think the amp has other issues & is going in for a physical.
     
  20. Electric I

    Electric I Member

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    Exactly.

    I'm just starting to learn tube amp circuitry & if I end up keeping the C30, a standby switch will be the first mod in line. Cheers
     

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