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Time for a retube...

Discussion in 'Amps and Cabs [BG]' started by Rumblefisher, Nov 27, 2010.


  1. Rumblefisher

    Rumblefisher Supporting Member

    Aug 22, 2007
    Astoria, NY
    ...of my Matchless Thunderchief. I don't know a whole lot about this, so a tech will be performing all the work. However, I will buy the tubes before they are installed, so I'd like some TB opinon.

    The TC is a 200 watt all tube Class A head, and I believe it originally came with KT100s. When I bought it, it had 4 KT88s, 2 of them blown (By the way, if I've used it with the blown tubes, have I damaged the amp?...haven't used it with any high volume at all).

    Should I go with KT88s? Can I use EL34s? 6CA7s? I've done the search and reading so I know the basic differences, but don't know which tube type would be best for this head. I definitely don't want to tax the amp and risk killing it.
    Thanks to all for their help, I desperately need it!
     
  2. Rumblefisher

    Rumblefisher Supporting Member

    Aug 22, 2007
    Astoria, NY
    Sorry to bump so quickly, I just wanted to add that there's an eBay auction ending soon for some really nice (supposedly) KT88s...if that's the way to go with this head then I'd like to bid for them. Thanks TB, I know some expert(s) will come through!
     
  3. Jim C

    Jim C Is that what you meant to play or is this jazz? Supporting Member

    Nov 29, 2008
    Bethesda, MD
    I would suggest using whatever tube type the manufacturer recommends and then pick a brand that you can afford (that also gets decent reviews).
     
  4. RoadRanger

    RoadRanger Supporting Member

    Feb 18, 2004
    NE CT
    It appears that only the KT88's will power it up to 200 watts - EL34/6CA7's are only good for half that.
     
  5. Rumblefisher

    Rumblefisher Supporting Member

    Aug 22, 2007
    Astoria, NY
    Sounds good...that's the route to go then. Thanks!
     
  6. Barkley

    Barkley

    May 15, 2009
    Vancouver
    Also thinking of retubing my SVT-CL's 6550s. Any affordable replacements that are warmer while keeping the clarity?
     
  7. RoadRanger

    RoadRanger Supporting Member

    Feb 18, 2004
    NE CT
    That would be the KT88's - but I'm not 100% sure if they require any rebiasing? I think they can just be plugged right in but I'm sure someone will be along shortly to confirm that :) .
     
  8. Barkley

    Barkley

    May 15, 2009
    Vancouver
    Thank you, Mr Kill! I'll look into it right now. I'll let you know about the biasing if I find out more!
     
  9. Barkley

    Barkley

    May 15, 2009
    Vancouver
    Turns out biasing has to be done.
     
  10. Indeed it does. Every time you replace output tubes the bias should be checked and reset as required.
     
  11. Barkley

    Barkley

    May 15, 2009
    Vancouver
    Would you also say that KT88's would make my SVT-CL sound better vs having 6550's in there?
     
  12. Rumblefisher

    Rumblefisher Supporting Member

    Aug 22, 2007
    Astoria, NY
    According to some experts on tb, tubes kind of sound the way they look. The thin, tall 6550s have more top end and can be "harsher" whereas the fatter KT88s have more of a bottom end.
     
  13. Barkley

    Barkley

    May 15, 2009
    Vancouver
    Hmmm... That makes things easier. Now to find tubes that are 11 feet tall and 15 feet wide!
     
  14. RoadRanger

    RoadRanger Supporting Member

    Feb 18, 2004
    NE CT
    I actually saw a picture of one like that - it was in a 2 megawatt VLF transmitter used to contact submarines circa 1960 :eek: .
     
  15. ranjam

    ranjam

    Sep 4, 2008
    Canada
    What kind of tech doesn't make an extra dollar selling tubes? He would know the amp and measure the B+ in that amplifier. KT88's or 6550's can take more B+, and have the most clean headroom. EL34's have much less headroom, and cannot take as much plate voltage. But the 'tech' should also know which tube he has better luck with in certain situations. And this is also based on what you want the amplifier to sound like.
     
  16. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
  17. Barkley

    Barkley

    May 15, 2009
    Vancouver
    Thank you so much for the help. I'll check out that link tonight. Where did you get your NOS GE 6550 if you don't mind me asking?
     
  18. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    i've been a tech since '73 and owned my own shop from 85-'05 so i stashed 48 of them away back in 1978 knowing that US tube companies (like GE) would soon stop making them. i'm down to my last dozen of them now.
     
  19. Barkley

    Barkley

    May 15, 2009
    Vancouver
    So no chance of getting them from you, huh? Hahaha. I'm gonna keep searching locally for now. :)
     

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