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  • Channels selector

    Hello. May I ask how to do a switching selector circuit which can switch between channels without any popping noise, please? I intend to use a manual rotary switch to select between channels but have no ideea how to make it to suprime the popping noise. Any help , please ? Thanks.

    Click image for larger version

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    "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

  • #2
    It needs a resistor from the right hand side of each coupling cap to ground.

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    • #3
      Originally posted by Dave H View Post
      It needs a resistor from the right hand side of each coupling cap to ground.
      Thanks. Mean a load to discharge the cap ? How big, please ? I can change the coupling caps if the order of resistors is relevant. 10M, 1 M, few hundred kilos...? May I use 10M to not load the stages too much in conjunction with 1M potentiometer and keep mostly the same time constant?
      Last edited by catalin gramada; 05-04-2020, 12:07 PM.
      "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

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      • #4
        Like that ...?

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        "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

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        • #5
          Ah! Too fast. I just took some time to put this together. But yes. Like that.

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          "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

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          • #6
            Thank You guys. Love ya!
            "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

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            • #7
              If you don't have 10 meg resistors around, I have always used 1 meg, of which I have a large number in stock. 1 meg has seemed large enough not to affect my tone. The value is not critical, just large enough not to get in the way.
              Education is what you're left with after you have forgotten what you have learned.

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              • #8
                Have a further question please. The circuit from picture is feasible? The goal is to not additional load the previous stages and get the quiet operation in same time. I wonder if dashed 10M grid leak will raise the voltage somehow due the grid current as time the tube is biased through cathode...

                Attached Files
                "If it measures good and sounds bad, it is bad. If it measures bad and sounds good, you are measuring the wrong things."

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                • #9
                  Provided the tone control you have in mind has a 0VDC reference for the following tubes grid I think this is fine. But loading you're concerned about if you were to use the typical 1M grid load off the switch is really very small. I just used Duncan TSC to mock up something quick. Using the Fender tone stack with controls at 5 and then with the circuit values altered to simulate no tone stack I loaded the circuit with what would be a 1M load and then a 10M load off the switch. You can see the difference is less than 1dB with the tone stack and much less than 1dB without it.
                  Click image for larger version

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                  "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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