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Replacing valves in TLA 5051

Discussion in 'Pro Audio Equipment' started by Gem, Mar 26, 2012.

  1. Gem

    Gem Active Member

    Hi, my first post here!
    I have just got a TLA 5051, and after replacing cheap Chinese 12ax7's (ecc83) for electro harmonix (Russian) ones, I am curious to know whether I can replace with ecc88's, as I hear these are nicer, and i have some amperex ones from holland, but do they have a different grounding pin config, and will this be bad for the 5051? The reason I ask, is although I have read up a lot recently about the difference between the valves, when I changed the valve (ecc83) from my Rode K2, to the advised, 6922 (ecc88) there wasn't a problem.. Yet there seems to be an advisory against using ecc88's instead of ecc83's .. Many thanks, for any light shed upon this.
     
  2. Boswell

    Boswell Moderator Distinguished Member

    They are not a direct replacement as (at the very least) the heaters are wired differently. The ECC83s have a 12.6V @ .15A heater wired between pins 4 and 5, but centre-tapped at pin 9, so by wiring 4 and 5 together you can supply the heater with 6.3V @ .3A between this point and pin 9. The E88CC has a 6.3V @ .3A heater on pins 4 and 5 with pin 9 being a grounded screen.

    I don't know how you had an ECC83 working in a Rode K2 as it's wired for the 6922/ECC88/E88CC. Here's a recent thread on that subject.
     
  3. Gem

    Gem Active Member

    Thanks, yes I saw that thread, but the K2 came with that valve (Mazda ecc83) in it! From new... So when I ordered a different valve, the 6922 came as a replacement.. Both work! Bizarre..
     

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