Simple Triode SE6V6 Amp

Discussion in 'DIY' started by je2a3, May 5, 2021.

  1. je2a3

    je2a3 Almost "Made"

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    [​IMG]
    This is the latest amp project in my blog which was originally configured for 1626 output tubes.

    [​IMG]
    I thought I'd share it here since it does a good job of driving my collection of orthodynamic headphones.

    [​IMG]
     
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  2. Tristan Jones

    Tristan Jones Acquaintance

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    Nice, simple, effective.

    JE lab stuff is always great.

    Those are some weird looking 6v6 tubes. I don't think I have ever seen one in a coke bottle with a round plate before.
     
  3. je2a3

    je2a3 Almost "Made"

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    Thanks for the kind words!

    Those are older versions of the 6V6.
     
  4. Tristan Jones

    Tristan Jones Acquaintance

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    Wait are you Mr. JE labs himself?

    If so, I have always wanted to get the opportunity to say thank you. You will never know the impact you have had on my life. One of my good friends built me an amp based off your designs, which lead me down a 10 year long journey. I have since learned how to design all my own gear, met many great friends, and if it weren't for covid, I would have started my own audio company.

    I would not be where I am today if it weren't for you. Everyone in my life has made an impact, but you were the only one I haven't been able to thank until today. So thank you so much for contributing to the diy community the way you have. It really has made a difference.
     
  5. Zampotech

    Zampotech Friend

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    The 6F5 tube has a high gain (~100). This reduces the gain of the output stage due to the use of cathodic transformer feedback.
    Something like this:

    [​IMG]

    Transformer cathode coupling will reduce the output impedance of the amplifier, reduce the amount of distortion, and refine the sound.

    The changes are minimal, it is necessary to wind a small number of turns on the output transformer.

    I think that the amplifier will surprise and please you after completion.
     
  6. je2a3

    je2a3 Almost "Made"

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    Guilty as charged! :)

    I'm glad my amp circuit has enhanced your musical pursuits!

    All the best!

    JE
     
  7. je2a3

    je2a3 Almost "Made"

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    Thanks!

    Back in the 90s, I tried a very similar circuit to the one you posted. It was 1/2 12AT7 capacitor coupled to a 2A3 using a Tango U708 output transformer which has a cathode feedback winding in the secondary. The schematic came from an MJ Audio Technology issue.

    Bottom-line was, it measured well and looked great on the scope. But I found it musically barren. I much preferred the sound of a high mu/low gm 6SL7/6SF5>45 or med-mu/med gm 76/6SN7>2A3 sans cathode feedback.

    YMMV, just sharing my experience.
     
    Last edited: May 15, 2021
  8. je2a3

    je2a3 Almost "Made"

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    Maybe this is the reason I didn't like the sound of cathode feedback. The Altec speakers I've been listening to since the mid-90s don't need as much damping as modern speakers require. IME, low Z output amps can kill the midrange magic these drivers are known for.
     
  9. Tristan Jones

    Tristan Jones Acquaintance

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    I have been trying for a long time to figure out what NFB is truly doing to the sound. All I have been able to come up with is that the fewer components you have in the NFB loop, the better.

    Simple schade feedback actually works surprisingly well where cathode feedback seems to sterilize the sound.
     

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