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Dual Power Supplies?

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  • #16
    A DPST switch then?

    Yeah, maybe I'll just leave the heaters be... I'm not likely to use one side or the other for more than 2 hours at a rime without a break. Definitely not gonna be using valuable tubes, except maybe an EF86 or two I have. Seimens, Mullard, a JJ. And a UOS 5U4GB.

    Justin
    "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

    Comment

    • #17
      Originally posted by Justin Thomas View Post
      A DPST switch then?

      Yeah, maybe I'll just leave the heaters be... I'm not likely to use one side or the other for more than 2 hours at a rime without a break. Definitely not gonna be using valuable tubes, except maybe an EF86 or two I have. Seimens, Mullard, a JJ. And a UOS 5U4GB.

      Justin
      No you need a big ole Dr Frankenstein Knife Switch mounted on top for effect at the church services you play. With some ole Doc Brown hair

      nosaj
      soldering stuff that's broken, breaking stuff that works, Yeah!

      Comment

      • #18
        I'm pretty sure one of the Marshall rack mount stereo power amps used the dual standby arrangement as you have outlined it.
        All heaters always running.
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


        ​

        Comment

        • #19
          Originally posted by g1 View Post
          I'm pretty sure one of the Marshall rack mount stereo power amps used the dual standby arrangement as you have outlined it.
          All heaters always running.
          Marshall series 9000 I think.
          https://drtube.com/library/schematic...-schemas#M9000
          nosaj
          soldering stuff that's broken, breaking stuff that works, Yeah!

          Comment

          • #20
            Oooh, thanks for all that, guys!

            Justin
            "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
            "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
            "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

            Comment

            • #21
              Sorry, I think I'm mistaken. The Marshall 9000 series are true dual mono amps with separate PT's for each side.

              The one I was thinking of was the Hughes & Kettner VS250, 4x6BQ5 per side, single PT. But it's standby switches lift the power tube cathodes for each side.
              Schematics here: https://music-electronics-forum.com/...ad.php?t=50681
              Originally posted by Enzo
              I have a sign in my shop that says, "Never think up reasons not to check something."


              ​

              Comment

              • #22
                <IF> I don't hafta worry abput having a speaker load attached, I'd consider alternative methods to silence either of the two sides...

                But like I said, it's pretty roomy so a couple extra switches won't bother me!

                Jusrin
                "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                Comment

                • #23
                  What if you used switching output jacks to engage the cathodes when they're plugged into. More intuitive in use. If a speaker is plugged in then it's getting powered. If it's not then that channel is effectively off. No chance that you might fail to have the standby in the wrong position and run the OT into an open load. I know switching jacks aren't notable for durability but there ARE some good ones and I think it's a more reliable system than leaving it to the player to always be cognizant of the standby switch. Even if (or especially if) that player were the builder.

                  EDIT: Just thinking about it,.. If you use plain old stereo jacks then the "ring" contact would effectively be on the mono jack sleeve when plugged into. If you are using un isolated jacks this could be used as a connection point for the power tube cathodes. In my experience the regular jack contact springs are more reliable than any isolated switches and such a jack can be purchased in an "open" style Switchcraft product. That should be sufficiently reliable I think. It also has the benefit of any likely jack failure rendering the channel off rather than any possibility of operating into an open load. In fact I may start doing this with my regular single output builds as a safety measure against open loads.
                  Last edited by Chuck H; 04-13-2020, 07:08 AM.
                  "Take two placebos, works twice as well." Enzo

                  "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                  "If you're not interested in opinions and the experience of others, why even start a thread?
                  You can't just expect consent." Helmholtz

                  Comment

                  • #24
                    Well then instead of switching jacks, how about TRS jacks. Wired just like the input jacks on effects pedals and how they complete the battery circuit. The ring terminal completes the cathode to ground whenever a TS plug is inserted.
                    Education is what you're left with after you have forgotten what you have learned.

                    Comment

                    • #25
                      Yup. You were posting while I was editing I think.
                      "Take two placebos, works twice as well." Enzo

                      "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                      "If you're not interested in opinions and the experience of others, why even start a thread?
                      You can't just expect consent." Helmholtz

                      Comment

                      • #26
                        For the record, I always use Switchcraft jacks & plugs unless I'm repairing an amp with a PCB. So I'll look into all of that. I just didn't think it was a great idea to leave a speaker jack shorted to safely kill output. I'll read over it when it's not 3:00a.m. That solution sounds cheaper, too...

                        Justin
                        "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                        "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                        "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                        Comment

                        • #27
                          Originally posted by Justin Thomas View Post
                          For the record, I always use Switchcraft jacks & plugs unless I'm repairing an amp with a PCB. So I'll look into all of that. I just didn't think it was a great idea to leave a speaker jack shorted to safely kill output. I'll read over it when it's not 3:00a.m. That solution sounds cheaper, too...

                          Justin
                          No no! Not a shorting jack, a stereo jack. Or TRS jack as Enzo indicated. The jack wouldn't short the output when unplugged, it would only connect the power tube cathodes when a male jack is plugged in. That way when no male jack is plugged in the power tube cathodes for that channel are not grounded. Which is actually used as standby for some amp models.
                          "Take two placebos, works twice as well." Enzo

                          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                          "If you're not interested in opinions and the experience of others, why even start a thread?
                          You can't just expect consent." Helmholtz

                          Comment

                          • #28
                            It's now 3:15a.m.!

                            So lemme get this straight. If the cathodes are ungrounded, I can leave all the other stuff (voltages - plate, screen, heater, bias) running, AND not blow up my OT if I don't have a speaker plugged in?

                            (No details right now, just "doofus-level concept) but, am I hearing this concept right?

                            Justin
                            "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                            "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                            "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                            Comment

                            • #29
                              And, I think TRS (STEREO) jacks come in shorting & non-shorting versions. I think. I'll look again. Do I want the NON-shorting Stereo Open-Frame Switchcrafties, right?

                              Justin
                              "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
                              "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
                              "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

                              Comment

                              • #30
                                Yes. Non shorting plain ol' Switchcraft "stereo" jacks. And lifting the cathodes from ground is pretty common. Used as a method of standby and also as a half power circuit where the cathodes of two out of four power tubes is lifted.

                                I hope you're still sleeping I didn't sleep well.
                                "Take two placebos, works twice as well." Enzo

                                "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                                "If you're not interested in opinions and the experience of others, why even start a thread?
                                You can't just expect consent." Helmholtz

                                Comment

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