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Svetlana 6L6 Bias BDRI

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  • Svetlana 6L6 Bias BDRI

    Hello all,

    I switched tubes in my BDRI. Jan Phillips 5771 (v1), tungsol ax7 (v2) and tungsol AT7 (v3). Power tubes are Svetlana 6L6gc. After playing for an hour the bias is reading 92.3V. Is this too high?

    The Svetlanas are orange and a slight blue colour. Pre amp tubes are orange. No red. Itís a nice sound and Iíd like to keep it around this setting, just donít wanna cook the tubes out too fast. Iím on a poor mans budget lol. If anyone could chime in, thatíd be great, special thanks!

    Jr
    The two greatest guitarists are American. The greatest Rock band is British. The greatest songwriter is Canadian.

    We are all connected. Peace n Love

  • #2
    Re: Svetlana 6L6 Bias BDRI

    Whatís your plate voltage?

    Comment


    • #3
      Re: Svetlana 6L6 Bias BDRI

      With the amp in standby the reading is 58V. With the amp fully on, the reading is 92.3V
      The two greatest guitarists are American. The greatest Rock band is British. The greatest songwriter is Canadian.

      We are all connected. Peace n Love

      Comment


      • #4
        Re: Svetlana 6L6 Bias BDRI

        Plate voltage is typically +\- 500v. Iím not familiar with your particular amp but all 4 of my tune amps read somewhere in that region (el34).
        I suspect your not reading the voltage correctly.

        Comment


        • #5
          Re: Svetlana 6L6 Bias BDRI

          What is a BDRI?

          Comment


          • #6
            Re: Svetlana 6L6 Bias BDRI

            Not your exact amp but Iíll bet it tells you what you need to know.

            https://youtu.be/19IUadZJf-c

            Comment


            • #7
              Re: Svetlana 6L6 Bias BDRI

              Originally posted by Lake Placid Blues View Post
              What is a BDRI?
              Blues deluxe reissue Iím assuming.

              Comment


              • #8
                Re: Svetlana 6L6 Bias BDRI

                More info backing the setting in the video.

                https://forums.fender.com/viewtopic.php?t=41432

                Comment


                • #9
                  Re: Svetlana 6L6 Bias BDRI

                  After looking up some information, the test point is for both tubes. The plate voltage is about 410v. With 6L6GCs, 92ma (mv = ma in this case) is 46ma per tube which is 63% of the plate dissipation. That's safe and not too hot or too cold.

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                  • #10
                    Re: Svetlana 6L6 Bias BDRI

                    Pretty clear you don't know what you're doing.

                    Take your amp to someone who does.

                    Comment


                    • #11
                      Re: Svetlana 6L6 Bias BDRI

                      Thanks for the help guys! The bias at 92ma seems hot but no cherry red. My strat sounds fuller. The 59 humbuckers in my sg really push the amp at this bias. There’s lots of distortion and overall much louder. Is this normal?? I’m thinking it’s just the hotter output of the Hums and there breakin up. Please correct me if I’m wrong.

                      Jr
                      The two greatest guitarists are American. The greatest Rock band is British. The greatest songwriter is Canadian.

                      We are all connected. Peace n Love

                      Comment


                      • #12
                        Svetlana 6L6 Bias BDRI

                        Originally posted by Jon Barr View Post
                        Thanks for the help guys! The bias at 92ma seems hot but no cherry red. My strat sounds fuller. The 59 humbuckers in my sg really push the amp at this bias. Thereís lots of distortion and overall much louder. Is this normal?? Iím thinking itís just the hotter output of the Hums and there breakin up. Please correct me if Iím wrong.

                        Jr
                        Your bias is waaaaaaay too hot man. 60mA
                        Didnít you watch the video I posted?

                        Comment


                        • #13
                          Re: Svetlana 6L6 Bias BDRI



                          "She was sounding really good just before the smoke & flames."

                          Comment


                          • #14
                            Re: Svetlana 6L6 Bias BDRI

                            It depends on the actual plate voltage of the specific amp. And if the power tubes are a matched pair. Reported plate voltages vary quite a bit from around 400v to 455 volts. So take it to some one that can safely measure the plate voltage of your specific amp.

                            Comment


                            • #15
                              Re: Svetlana 6L6 Bias BDRI

                              Don't scare the OP. 30 ma per tube is only 60% if the tubes are 5881s and the plate voltage is as high as 455. If the tubes are 6L6GC then it's less than 50% plate dissipation, even at 455 plate volts. That's pretty cold. But the tubes are more likely to last past the warranty. As the current increases the plate voltage will drop some too.

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