Do I have to rebias my old Magnatone 210(single 6V6) after a tube swap?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by yesteryear, Jun 5, 2006.


  1. yesteryear

    yesteryear Member

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    Its an old 210. Just got it and fired it up. Im getting some crackling/static noise. This is remedy when I hold the 6V6 still with a towel of course. Hmmm, microphonic tube, fair enough. Its an old KEN RAD. So I swapped out the KEN RAD for an old RCA that I have in my tweed champ clone. This caused the amp to sound really quite and obvious crappy fizzy, static distortion. When I sawp tubes in my Champ I never get this. I figured cause its single-ended etc. that a tube swap was ok without rebiasing. Any idea what this could be. The old RCA is a NOS metal one from the 50s or so.Like I said , it works fine in my champ. Anyone have any tips how to remedy this? Amp sounds fantastic other than the static. The vibrato is all that people say it is. Very trippy and horror movie like[​IMG] This sucks cause I know its something very small but damn I just want to crank the amp and see what its got.
     
  2. mc5nrg

    mc5nrg Supporting Member

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    My guess as a non tech is that you have a dirty tube socket that may also need to be tightened.Assuming the amp is cathode biased the general rule is that rebiasing is not necessary.Sometimes metal tubes can cause problems with short circuits and related problems depending on the amp circuitry,how the socket is wired etc.

    Have you checked out the Yahoo Magnatone-Valco users group yet?
     
  3. Dave C

    Dave C Gold Supporting Member

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    +1 on the dirty tube socket and metal tube . Could also be caps or noisy resisters too , but I'd start with cleaning sockets and swapping some tubes first.
    Dave C
     
  4. yesteryear

    yesteryear Member

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    So the original tube glass KEN RAD was just cooked. Metal didn't work. However another old glass RCA works like magic. No static just nice tone. Weird.
     
  5. songsmith1950

    songsmith1950 Member

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    Another vote for the tube socket. I have seen before where changing out tubes a few times could actually knock enough tarnish off a troubled pin in the socket to make it work.

    It may come back and it may not. If you don't want to retension it perhaps some of the old fashioned tuner spray might clean it, if it is still available.

    Tom
     

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