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7199

  1. B

    Caution on using 6GH8, 7687, 6U8 tubes to replace 7199 or 6AN8 in phase splitter circuits

    The pin out for the 6GH8, 7687, 6U8 tubes has a design weakness when used in a phase splitter circuit that can cause high frequency stability issues with some amplifiers originally designed for the 7199 or 6AN8 tube. The 6GH8, 7687, 6U8 tubes all feature the pentode grid (pin 2) right beside the...
    • Bob@Blue5
    • Thread
    • 6an8 6gh8 6u8 7199 7687 high frequency stability phase inverter phase splitter
    • Replies: 39
    • Forum: Tube Audio
  2. R

    Thoughts on restoring a Dynaco ST70

    Hi everyone, I recently came in possession of an ST70 factory wired, all original components. Other than a hum in one of the channels that I traced to the 7199 tube on one side, it's fully functional. I'm very comfortable around electronics but I am relatively new to tubes. I want to ask you...
    • radu_c
    • Thread
    • 7199 dynaco gz34 restoration st70 tubes
    • Replies: 62
    • Forum: Tube Audio
  3. CoolOhm

    7189 Monoblock Project

    Hello: I am posting this in the hopes someone can shed some light on some nice old iron I just acquired. I have two nice PTs and two nice ultralinear OPTs, all pulled from two mono 6BQ5 ∕ 7189 amps. These were taken from organs from the early sixties. The amps have 6GH8s and EL84s in...
    • CoolOhm
    • Thread
    • 6hg8 7189 7199 electrohome monoblock s-5000 sherwood
    • Replies: 24
    • Forum: Tube Audio
  4. artsybob

    Next Project: Andrea CPR-A2S Console

    Now that I'm done restoring my Realistic SAF-40D integrated amp I've been looking for a new project to work on. I think I'll start working on my uncle's circa-1961 Andrea CPR-A2S stereo console. I couldn't get many decent interior shots, but it looks like it has a pretty sweet amplifier with...
    • artsybob
    • Thread
    • 1961 7199 andrea radio company andrea tube console console stereo el84 tube amp
    • Replies: 8
    • Forum: Tube Audio
  5. J

    ST70 7199 / 6GH8A amplitude vs frequency

    Ive posted a 1 off video showing my issue of the amplitude change of the 7199 outputs in which the change increases with the frequency. I found something, however even though it corrects the amplitude, the phase does not align, tested with both a 7199 and a 6GH8A Surely this is masking another...
    • JRUBIN
    • Thread
    • 6gh8a 7199 frequency imbalance phase st70
    • Replies: 102
    • Forum: Tube Audio
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