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Screen grid resistor - 6V6 6L6 swapping

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  • Screen grid resistor - 6V6 6L6 swapping

    I built a Pricenton BF based amp. It runs at 420V with SS rectifier and 380V with tube rectifier.
    With proper bias (and rectitier and OT matching) I believe the amp could run either 6L6 and 6V6.

    I used 470R screen grid resistors.
    Is this a good choice for either 6L6 and 6V6?
    Should you reccomend higher values?

    Thanks in advance

  • #2
    I was doing the same with a 5f1 champ I built, wanted to try it with a 6l6 and someone here, Loudthud suggested that I keep the value of the resistor the same , 470 ohms, but up the wattage from a 5 watt R to a 10 watt.
    Hope this helps.

    Comment


    • #3
      Originally posted by pontiacpete View Post
      I keep the value of the resistor the same , 470 ohms, but up the wattage from a 5 watt R to a 10 watt.
      470 10W for each 6L6 or 6V6
      I'm surprised... seems too much

      For what I remember Fender BF amps have 2 or 3 W for each screen grids.

      Comment


      • #4
        Originally posted by pontiacpete View Post
        470 ohms, but up the wattage from a 5 watt R to a 10 watt.
        Well, you were referring to the power tube's cathode resistor.
        My question is about the resistors from power supply to power tubes' screens.

        What is the best value for 6V6-6L6 swapping?

        Comment


        • #5
          Originally posted by bluemonk View Post
          I used 470R screen grid resistors.
          Is this a good choice for either 6L6 and 6V6?
          I think 470 1W would be OK for either. You'll see these in both 6L6 Fenders and the 6V6 Deluxe Reverb for example.
          "In theory, there is no difference between theory and practice. In practice there is."
          - Yogi Berra

          Comment


          • #6
            Originally posted by bluemonk View Post
            Well, you were referring to the power tube's cathode resistor.
            oops, yes, I was. sorry. My mistake.
            Last edited by tboy; 10-11-2009, 04:39 AM. Reason: quote repair

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            • #7
              Originally posted by JoeM View Post
              I think 470 1W would be OK for either. You'll see these in both 6L6 Fenders and the 6V6 Deluxe Reverb for example.
              That's right. Just wondering if higher values (say 1k) would preserve tube life and amp stability.
              I'm going ro leave in place the 470-3W I already put.
              Thanks

              Comment


              • #8
                Originally posted by bluemonk View Post
                That's right. Just wondering if higher values (say 1k) would preserve tube life and amp stability.
                I'm going ro leave in place the 470-3W I already put.
                Thanks
                I don't normally let this out. But, 1 K is the value I use for both the 6V6 and 6L6. Both of these power tubes already are fairly robust, with the 6V6 being on the top. If long tube life is one of your goals, then keep tabs on the filament voltages and put a small fan on the tube glass. Just because tubes run hot, does not mean they like being run hot.

                -g
                ______________________________________
                Gary Moore
                Moore Amplifiication
                mooreamps@hotmail.com

                Comment


                • #9
                  Originally posted by mooreamps View Post
                  I don't normally let this out. But, 1 K is the value I use for both the 6V6 and 6L6. Both of these power tubes already are fairly robust, with the 6V6 being on the top. If long tube life is one of your goals, then keep tabs on the filament voltages and put a small fan on the tube glass. Just because tubes run hot, does not mean they like being run hot.

                  -g
                  470-510 ohms = signal "shaping" fuses*.

                  1-2K ohm = screen "compression" moderating resistors.

                  >2K ohm = screen "voltage dropping" resistors.



                  * NOTE: amps use fuses, bombs use fuzes.
                  Last edited by Old Tele man; 10-11-2009, 03:26 AM.
                  ...and the Devil said: "...yes, but it's a DRY heat!"

                  Comment


                  • #10
                    Originally posted by bluemonk View Post
                    For what I remember Fender BF amps have 2 or 3 W for each screen grids.
                    It's a large resistor, but it's an Allen Bradley 1 Watt CC

                    Larry
                    The fault almost always is sitting in front of the amp

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