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Ampeg SVT CL Tube Question

Discussion in 'Amps and Cabs [BG]' started by Kuchar, Mar 30, 2015.

  1. Kuchar


    May 31, 2006
    Hello everyone, it's been a while.
    I did try to use the search function to get an answer to my question but the results were rather bloated and couldn't really find what I was looking for.

    I had a really long practice session (about 6 hours) and toward the end my Ampeg SVT CL went into fault mode (red green flashing light). One of the tubes in the back is no longer glowing when I power it up. I read somewhere that blown tubes will still glow? Is this most likely a bad tube or could it be something else?

    I'm going to take it to a tech but wanted to get some advice beforehand. I don't really know any well known techs around my area (Detroit Metro) so I just kind of take it to whomever I can find, which is why I would like to be informed before going in.

    If this is a tube problem, can anyone recommend an affordable set of tubes? The last time I took my head in (about 2 years ago?) the tech said that both sets of power tubes were really wore and about to go out. I didn't end up replacing the tubes, but should I replace both sets this time if thats the case? Or keep one of the worn sets with a brand new set?

    Thanks for any advice!
  2. jastacey

    jastacey Supporting Member

    Feb 8, 2009
    I'd take it to a tech ... if one of the power tubes is not lighting up, usually means a deeper problem, maybe one of the screen resistors opened up, as to power tubes, I just re-tubed my SVT-CL and I used the Sovtec 6550, also you should replace the driver tubes 12AU7 x2 .... do you know what tubes are inside? I purchased a set from this place, 6550 / KT88 / KT90 / KT120 tubes in stock now
    If your tubes are somewhat fresh just get a replacement or a set of 3, as the amp runs 2 sets of triplets, all this is providing the tubes test good on a reliable tube tester
  3. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    If one tube is blown and the others are in good shape, you can send them in to a good tubes reseller (such as the one that Stacey mentioned above, very good place) and they will match a replacement with the rest of the set. This can save some money. But the screen resistors should still be checked as was mentioned.
  4. Kuchar


    May 31, 2006
    Thanks for the replies! I'm not sure what kind of tubes are in the amp right now. Does it matter if one set of 3 is different then the other set of 3?
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Even any trio doesn't need to consist of three of the same make of tubes. As long as they match.

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