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Do I need to bring a set of spare tubes? (SVT-CL)

Discussion in 'Amps and Cabs [BG]' started by jansenh, Sep 16, 2008.

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  1. jansenh


    Nov 22, 2005
    So, earlier tonight while rehearing with my band, my precious SVT Classic amp suddenly made a farting sound, a flash of blue light and then a bang. And then it died. Kind of killed the mood in the studio, no more rehearsing tonight! My second amp, the Ashdown, was at my home, 45 km away, and not an optionÂ… Going back to the store with it tomorrow. I got the amp brand new less than 8 weeks ago!

    I have played it at 6-8 rehearsals, 3-4 hours each time, and one live gig. Playing fairly loud, but the thing is built to cope with that?

    The yellow and green light flashed, and the manual states that this might be a problem with the circuits related to the tubes in the amp... Hopefully it's just one of the power-tubes that called it a day, they can easily be replaced (?). Strange thing,.. made me think of maybe carrying a spar set of tubes to gig's?

    Henning - Norway
  2. Suppose you carry a "spare set;" what happens if you actually DO have tube failure which takes out a couple of major resistors? How do you propose to install, repair the amp, and calibrate those tubes in the five to ten minutes you might have at a gig? IOW, NO.
  3. jansenh


    Nov 22, 2005

    Point taken.
  4. xshawnxearthx


    Aug 23, 2004
    new jersey
    ahh the beauty of having a all tube head. the need for a solid state back up at all times.

    when i had my 400+ i kept a 500 watt power amp in our trailer just incase.
  5. Funny that bands manged to get by with all tube amps for decades without any solid state backups for decades. :rolleyes: A properly set-up tube amp is no more unreliable than any solid state amp.
  6. jvdb


    Jul 26, 2006

    But it's always a secure feeling to have a backup... no matter how reliable your amp is. For bigger shows with a decent PA I only bring my Sansamp as a backup, for smaller gigs I have an Ampeg AP 3550 and a Sansamp RBI to back up my SVT.

    But spare tubes... no.
  7. I played hundreds of gigs for years with ONLY an all-tube amp. In that time, I had to loan my rig to bass players in other bands at shows whose solid state amps had died quite a few times. If you don't trust your amp to play out with, either get it fixed so that you can or get another amp.
  8. adam precision

    adam precision

    Mar 26, 2008
    Yeah, but the bigger bands had all tube backups sitting right next to there main rig (and they still do).
    But i agree that a properly set up tube amp should be reliable, although this is getting harder with all the poor quality tubes around now.
  9. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    I thought the SVT was designed to take the failed tube(s) out of the circuit and keep going on 4 power tubes....did they toss that feature out in the Classic?
  10. Big bands today also duplicate solid state rigs. It's not because either technology is inherently unreliable, but that competent repairs or equivalent replacements on the road are VERY hard to come by. I'll never forget when I saw the Chili Peppers and NONE of Flea's 2000RB's worked.

    Tube quality now is probably better than the last ten-twenty years of "original" tube production. There's still a lot of crap from the late 80's early/90's out there, but most new stuff is really good.
  11. The SVT uses 1 watt screen grid resistors. In the event of tube overcurrent these burn up and "turn-off" the tube, leaving the rest of the output tubes unbalanced.
  12. lowendgenerator


    Mar 26, 2006
    Get that head to a tech, or even the place you bought it and have it thoroughly checked out. A blown power tube, as mentioned, can burn up other components. Tubes should last a long time. Years, not weeks.
  13. Fretlessboy


    Nov 29, 2007
    St Augustine Florida
    Endorsing artist GENZ BENZ/HERCULES STANDS/XSonics
    I would take it to the best tech you can find and not only have it fixxed but have him tell you why it happened. I ran a 1972 SVT untill 2003 and never had a failure. The key is finding out why it failed.
  14. xshawnxearthx


    Aug 23, 2004
    new jersey
    like me re-word that.

    you don't NEED to bring a tube amp, but it's something smart. our guitar players always bring a back up head when we gig. as did i when i had my all tube head. we all have had tubes go and amps **** the bed on us. it's better then having to be on stage and ask other bands to borrow gear.

    i still carry a ss power amp for my 4 pro.
  15. Matt R.

    Matt R.

    Jul 18, 2007
    Huntsville AL
    Have had my SVT CL for almost 4 years without issues. Gigs 3-5 nights a week. No solid state backup needed. Just find out the issue and get it fixed/replaced. Best of luck:bassist:
  16. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Which is not the same as a fix, since those two remaining tubes are now working harder, into a lower plate load....

    There really isn't a "designed-in" safety circuit in an old SVT...... but then, a tube amp doesn't really need one. The CL actually sort-of has a safety circuit....... which was deleted for the VR....!

    You can short a tube amp and it won't blow, like an SS will. Might get hot, might drain some tube life, might even mess up the tubes if you really keep it up, but generally will not do the "expensive failure in a half second" trick that an unprotected SS amp will (and some protected amps also).
  17. seamonkey


    Aug 6, 2004
    Spread the fear. Many SS have no problems with a short. They self protect. And a short is much less likely to happen than an open circuit. You can run a SS wide open with no load unlike a tube amp.

    Markbass has put all kinds of protection on the Classic 300 head. It might have raised the bar on tube reliability. Time will tell. It self biases, so carrying spare tubes should be no problem.
  18. jansenh


    Nov 22, 2005
    I got the amp fixed yesterday at the store. The guy usually dealing with tube-amps is on vacation; they replaced all the tubes...

    I will still have a word with their tube/bass repair guy and figure out what went wrong.

    regards, Henning - Norway
  19. I realize this is just more of your anti-tube/anti-vintage propoganda, but it's REALLY low down of you to imply that Jerrold has any other agenda than simply being factual, which he most certainly is. It's pure irony that he makes simple, factual statements about amps that stem from his years of design and repair work and because you've decided that anything to do with a positive portrayal of a tube amp is wrong, you question his motives, even though you lack ANY technical basis to do so.

    This is ONLY the case with an amp with extra shorting protection built in, and unlike tube amps as Jerrold pointed out, not inherent to the basic amplifier circuit. Even though such protection is common it is accomplished with extra circuitry and is NOT endemic to a basic solid state design.

    Untrue. As a matter of fact, the European saftety regulations that brought about Speakons as standard equipment on most amps were drafted to address amplifier output shorts.

    ...and what, pray telll is that "protection?" They cannot even accurately rate its output power, a VERY basic aspect of design. I certainly won't believe they've pushed the state of the art in tube amps until I see their "protection" in action or some technical explanation beyond your blind enthusiasm.
  20. Please keep us updated. I doubt a blind retube will solve your problem.

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