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Ampeg SVT Tech Help (full tube that is)

Discussion in 'Amps and Cabs [BG]' started by Dave W, Aug 23, 2012.


  1. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    I just pulled out my SVT-II Pro to play with. It hasn't been biased in I don't know how long. I figured going through the bias procedure in the manual was a good idea since it wasn't correct when I turned it on.

    I'm starting to wonder if one of the tubes is bad. It sounds totally fine, and it seems to bias correctly, but one of the middle 6550's isn't lit up or warm at all. Every other tube in this thing is glowing a nice healthy orange. It is my understanding (albeit, small) that the bias lights would not be happy green if one of the tubes was bad.

    The tube in question looks a little toasted compared to the others. The "mirror paint" in the top of the tube is pretty much gone, and there are some grey spots on the glass on the sides of the tube.

    Any thoughts? I'm not against taking it to a tech, but if I could do a little troubleshooting first that would be great.
     
  2. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    If one tube is cold then most likely it's bad. You could try moving the tube to another position and trying again. This will tell you if the tube is bad, it remains cold in the new position, or the socket it bad, the tube works properly in the new position.

    That's about all you can do for troubleshooting.
     
  3. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    I'll definitely give that a shot a see what happens...
     
  4. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    Yup, the tube is still not glowing or warm when moving to a different location. So that's more than likely a bad tube, right?

    When replacing, does this mean that I need to purchase a matched duet? Does that duet need to be matched with the others? Right now it's got a full sextet of Russian Tung-Sol 6550's
     
  5. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    The best, safest, and most logical option is to take it in to a good tech. That way, you get a fully functional amp back, with no problems, known or hidden.
     
  6. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    That's what I'm looking into right now. I just don't want to spend $500 to get it working again if I don't really need to. Since it's my largest and heaviest amp by quite a wide margin, it's only going to get gigged on rare occasions.
     
  7. the valve has had it, replace with one of a similar bias
     
  8. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    Welp, quote #1 just came back. $125 /hr plus the cost of parts. He did mention that it would probably only 1-1.5 hrs pending it's just a bad tube. That's to replace the full sextet, bias, clean everything, do an AC balance, and test it. Is that a good price, high price, or low price?
     
  9. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Rates will vary depending on where you live. They tend to be higher in larger cities, as are the cost of many things.

    You commonly see rates of $75 and up; $125 is not unusual for someone good.

    There are a lot of hacks out there so you have to be careful who you deal with. A good tech will know how to fix the amp properly and quickly. I would find the best person to do the work rather than worry that the job might cost a little more. If you have an SVT expert that knows what they are doing, whatever they charge is worth it.
     
  10. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    The quote is from Fuchs. I'd say they are good and know what they are doing!
     
  11. I'd ask em if taking the amp out of it's casing will save em some time & you some $$
    I do this when taking an amp to my tech. He'd always told me it'd save him time/me money doing so.
     
  12. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    For someone who has no experience inside an SVT this advice might do more harm than good. There are voltages in there that stay for quite a while and can still kill.
     
  13. Alex1984

    Alex1984

    Jan 16, 2010
    Vancouver
    125 seems a little high, and I don't think retubing the full sextet is really necessary. People here (eg. JimmyM) have been known to replace individual tubes only when needed and at most, maybe you should replace a matched triplet of tubes if you're so inclined.
     
  14. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I do have to say that I don't actually recommend only replacing one with a non-matcher, but I did it recently and my SVT works fine ;) But one thing I do recommend is replacing only three at the most for one bad tube.
     
  15. hodgy

    hodgy

    May 5, 2004
    Bothell, WA
    Customer Support- Ampeg/ Line 6
    Dear god, if you're going to get raped by a tech, at least let me rape you for half the price.
     
  16. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    That's hot!

    BTW, my local tech charges half price for a bench charge, too.
     
  17. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    Yeah, no experience whatsoever. Plus it looks like a lot of work to pull it our of the rack enclosure. With some instruction I'd be more than capable of discharging the caps and checking other things.

    Well, it's running on 5 right now and still works okay. But I'm not pushing my luck with it and running it any further.

    As for replacing 3, that's what I was thinking of doing. Actually, I wasn't sure if I could do 2 or 3.

    It would be nice to have it get the full once over though, but I'm not interested in paying that much to do it right now.

    So I guess that's a high price to you?
     
  18. Alex1984

    Alex1984

    Jan 16, 2010
    Vancouver
    Yes, $60~90/hr is what my local techs charge. SVT tubes run in 2 sets of triplets.
     
  19. Dave W

    Dave W Supporting Member

    Mar 1, 2007
    White Plains
    I'll keep shopping around. That was just the first tech that came to mind that is within easy enough driving distance.

    I've only ever taken a tube amp to one tech, and he was terrible. $400 and 3 months to work on my amp (a guitar amp) and when I finally got it back it still had the problem that I took it in for in the first place.

    So I'm trying to get some recommendations for around here...Westchester County NY for anyone that has a recommendation :) I'm not against going to another county, LI, CT, or NJ (where Fuchs is) either...
     
  20. SigiZ58

    SigiZ58

    Aug 23, 2012
    My Tipp is this:

    Look here:
    http://www.tube-town.net/ttstore/index.php/cat/c315_KT88---6550.html

    They sell for a good price - matched!
    Not long ago I bought the JJs (momentan the most reliable 6550 as the shop owner says). They have a forum also.
    If you decide to change only a triplet, be aware the tubes are in a strange order - like Vs. There in the forum I posted some time ago some information about the SVT II Pro with pictures and showing the position of the tubes
    http://www.tube-town.de/ttforum/index.php/topic,15015.msg148007.html#msg148007

    One tube is 30,- Euro (maybe you can save the VAT, then it is less) This means: 6 Tubes 180,- + shipping 57,- to USA

    For that price you have a matched Sextett with new tubes!
    And you could buy 7 instead of 6, if one should be bad ( but he, Dirk, checks the tubes before shipping)

    No, I am not involved in that shop - only happy customer :)

    Greetings from an Ampeg SVT II PRO User :)
     

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