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ampeg re-tubing question

Discussion in 'Amps and Cabs [BG]' started by grindmore, Jan 31, 2004.


  1. grindmore

    grindmore

    Jun 21, 2002
    brooklyn
    i have a vintage 70's ampeg v4b. i am looking to retube it for maximum wattage and volume. i am not really keen on dropping tons of dough on the old 7027's. what is a good replacement with out any mods. i have been looking at tesla JJ EL34's and electro harmonix 6L6GC's. any input is appreciated. i run a jazz bass through a sunn 4x10 with an occasional big muff in a loud rock/noise band. thanks.
     
  2. What makes you think you need new tubes?
     
  3. grindmore

    grindmore

    Jun 21, 2002
    brooklyn
    well, right now it has an unmatched quad in it. i figured since i recently purchased it, and not knowing its history, i might as well start fresh.
     
  4. Before you spend money on new tubes, you'd be better off to have a tech check the amp with the ones that are in it. Even if they are obviously different brands mixed together, they may be "matched" in the amp. If they need replacing, the tech can make that determination and also do the replacement and required rebias. He can also check the amp to see if any parts are failing that could cost you big bucks to fix later if they go and damage other stuff. Output tubes MUST be rebiased EVERY time they are changed. Just sticking a new set in the amp is a crapshoot. If the bias current is set too low for them, you'll toast your brand new tubes AND your amp.

    BTW, you CAN'T use EL34's in that amp without serious mods. They're not the right tubes, and they wouldn't sound as good even if you did mod the amp. There are two options for replacing the 7027's that came in that amp: 6L6GC's and 6550's. Both are drop-in replacements and only require a rebias, which you SHOULD be doing anyway. The only caveat to 6550's is that you need to monitor their heater current draw, as some V4's had weak power transformers and they could burn them out, a VERY expensive repair.