Traynor YBA-1a tubes

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by GaryE, Feb 9, 2015.

  1. GaryE

    GaryE Member

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    Hey, I have a 1970 Traynor YBA-1a on the bench this week and need some tube info. Since this is the high voltage version with about 540 volts on the plates ,I was looking for recommendations on a new set of
    6CA7 power tubes for it.Which of the new brands can handle this voltage? I am repairing it for a friend who doesn't wish to go the NOS option as he will likely sell it when i am done . Thanks in advance!
     
  2. Primakurtz

    Primakurtz Member

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    The EH 6CA7s in my YBA-1a seem very happy.
     
  3. GaryE

    GaryE Member

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    Thanks! I was thinking about those ones.Have they lasted a while?
     
  4. fakeox

    fakeox Member

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    I'm using KT120s in my '72.
     
  5. GaryE

    GaryE Member

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    Wow! That must be a beastly huge sounding amp!
     
  6. fakeox

    fakeox Member

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    Right now it's cathode bias only, 65ish watts, very low feedback. It sounds like the worlds biggest Tweed Deluxe. Next time in it will also do A/B & hopefully do 115-120 watts.
     
  7. donnyjaguar

    donnyjaguar Member

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    I'm running EL34 Ruby tubes in my last build which presents 530-540V to the plates. No issues in two months or so.
     
  8. GaryE

    GaryE Member

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    That's good to know, guys. I will probably go with whatever the local supplier has, and probably do the dual 1k 5 watt screen resistor mod as well. Anyone done this?
     
  9. jcs

    jcs Member

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    Definitely do the screen resistor mod......otherwise you will 'potentially' have problems.
     
  10. fakeox

    fakeox Member

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    Nah, the KT120s are just cruising at 540v. Good idea with skinny bottles tho..
     
  11. GaryE

    GaryE Member

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    [​IMG][/URL][/IMG]Wow! what a great day! Went out looking for a set of 6CA7 tubes for this amp and could only find a set of JJ tubes,until someone said they had a pair of some older NOS tubes. These little beauties are XF2 Mullards in Rogers boxes!!!I couldnt pay the 75.00 fast enough!The customer will be getting a nice ANOS set of RFT 6CA7s that I had been keeping for myself.You never know what the day will bring you!
     
  12. EpiglottisDynasty

    EpiglottisDynasty Member

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    I have one of these, and it has arced over the plates with both TADs and JJ EL34s. The latter set lasted for over a year of pretty much being the house bass rig for a venue though. I think some of it has to do with my cab being terrible and vibrating the head like mad. The dead tubes rattle like burned out incandescent bulbs. I've biased it colder and I put the head on the floor now, we'll see what I get out of this set.
     
  13. Blue Strat

    Blue Strat Member

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    What's the screen voltage? That seems to be the deal breaker where high plate voltages are concerned.
     
  14. EpiglottisDynasty

    EpiglottisDynasty Member

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    Schematic says 525V on the grids, but that is at whatever mains voltages generally were then. Mine actually reads about 560V.
     
  15. GaryE

    GaryE Member

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    That's similar voltage to the one I just worked on .
     

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