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  • Traynor YCS50 bias issues?

    Hi I have a Traynor YCS50 combo amp. When I try to adjust the bias the lowest I can get is 88 mV and Traynor calls for 75 mV. Should I be worried? My power tubes are Ruby 6L6

    ​Thanks
    ​Rick
    Last edited by Rickvl; 04-28-2017, 06:19 PM.

  • #2
    Originally posted by Rickvl View Post
    Hi I have a Traynor YCS50 combo amp. When I try to adjust the bias the lowest I can get is 88 mV and Traynor calls for 75 mV. Should I be worried? My power tubes are Ruby 6L6

    ​Thanks
    ​Rick
    You can measure the bias dissipation in mV, but the recommended method to measure a 6L6 is in mA. A individual 6L6 dissipates a maximum of 25W . To bias it properly you should set it to 35mA (70% of max) and this will guarantee that you are not running it too cold and are clear from being in crossover distortion. This is assuming that your Traynor's plate voltage is in the neighborhood of (450-480)DCV.

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    Set your DMM to Amp/200m to adjust the bias and you'll be fine.

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    • #3
      Originally posted by Cyborg View Post
      You can measure the bias dissipation in mV, but the recommended method to measure a 6L6 is in mA. A individual 6L6 dissipates a maximum of 25W . To bias it properly you should set it to 35mA (70% of max) and this will guarantee that you are not running it too cold and are clear from being in crossover distortion. This is assuming that your Traynor's plate voltage is in the neighborhood of (450-480)DCV.
      The Traynor YCS50 has 2 ohm resistors in series with the cathodes of the output tubes.

      Measuring the voltage drop across the resistors - via the convenient test points on the outside of the chassis - is a quick and easy way to measure the current flowing through the tube and adjust the bias.

      The recommended setting of 75mV corresponds to 37.5mA and the OP's measurement of 88mV corresponds to 44mA


      As a human being, you come with the whole range of inner possibilities
      from the deepest hell to the highest states.

      It is up to you which one you choose to explore
      .

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      • #4
        Here's the service Bulletin.

        I can say, I've tried Ruby Tubes in my Fender Bassman about a year ago and had to immediately remove them. sent them back for another set and they were even worse. They both produced hissing and popping noises. Horrible tubes from my experience. Ruby doesn't make tubes, they simply buy them from China, match sets and brand them.

        Then tried JJ's (which I didn't like) for a short time. They worked but I didn't like the hiss levels or tones they produced. Made the amp sound like it had a blanket over it.

        I later replaced them with Electro Harmonics which totally rock. Low noise, Excellent gain and frequency response. Reminds me of the old RCA tubes I used to use. I went with they're preamp tubes and the amp sounds much better then the Groove tubes I had in there.

        Click image for larger version

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        • #5
          Originally posted by WRGKMC View Post
          Here's the service Bulletin.

          I can say, I've tried Ruby Tubes in my Fender Bassman about a year ago and had to immediately remove them. sent them back for another set and they were even worse. They both produced hissing and popping noises. Horrible tubes from my experience. Ruby doesn't make tubes, they simply buy them from China, match sets and brand them.
          Interesting you mention this. I have a Vox Night Train 15 combo that I never seemed to be able to dial in quite right. On a whim I swapped the 12ax7 ruby tube in v1 that came with the amp for a Tung Sol & the difference was dramatic (seemed to smooth out the amp & make it less "snotty" sounding).

          I don't know if the other tubes in this amp are Rubys as well (they're just generic looking with a Made in China logo on them & didn't say Ruby like the one I replaced), but when I get a chance I'll be swapping them out as well.

          I used to think tubes didn't make a difference in tone but I'm now a convert.

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          • #6
            Originally posted by thatsbunk View Post
            ... I used to think tubes didn't make a difference in tone but I'm now a convert.
            The very thing that makes tube amps great is also their weakness.
            As a human being, you come with the whole range of inner possibilities
            from the deepest hell to the highest states.

            It is up to you which one you choose to explore
            .

            Comment


            • #7
              Originally posted by onelife View Post
              The recommended setting of 75mV corresponds to 37.5mA and the OP's measurement of 88mV corresponds to 44mA
              38mA per 6L6 is good, a little hot and will limit to some degree the PT life. If you are striving for a warmer but somewhat gritty result then you're good there. A 6L6 set to 35mA gives you the best of both worlds, tighter, a bit more percussive (not as in a EL34) and still produce that classic Fender tone.

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