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  • Pot input noise issue

    Hello, I received a certain amount of ripple noise when the volume pot goes down. It started at the end of the track (less above 5 percent to the end, than constantly till the pot is closed). Seems is not a pot issue as shunted the wiper to ground have same effect. It is normal ? Bad tube? Bad designed circuit, please? The noise is very low , but is there.Over there the amp is quiet as mouse. How can get ridof, please.Thanks.

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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
    Originally posted by catalin gramada View Post
    Hello, I received a certain amount of ripple noise when the volume pot goes down. It started at the end of the track (less above 5 percent to the end, than constantly till the pot is closed). Seems is not a pot issue as shunted the wiper to ground have same effect. It is normal ? Bad tube? Bad designed circuit, please? The noise is very low , but is there.Over there the amp is quiet as mouse. How can get ridof, please.Thanks.

    [ATTACH=CONFIG]53700[/ATTACH]
    Did you try increasing the value of input grid resistor? Something more common, like 68k?

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    • #3
      Originally posted by m1989jmp View Post
      Did you try increasing the value of input grid resistor? Something more common, like 68k?
      Nevermind, I removed the 10k grid stopper from input and everything go smooth without any bump noise. Rising the value, I think will go worst as will pick up ripple from ground path. Is interesting and have no ideea why it act as a switch at the end (beginning) of the pot track.Thanks


      Late edit: anyhow what I remarked, 12AU7 sound bad unbypassed in my circuit, I heard will do at serious ammount of current. I raised it till 7mA and still no good enough, for me at least. It was claimed it generate serious amount of distortion,but for low excursion guess is no a concern
      Last edited by catalin gramada; 05-26-2019, 05:15 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
        'Ripple noise' normally means HT ripple, eg 100Hz hum (as I think you're in Europe); is that what you meant here?
        My band:- http://www.youtube.com/user/RedwingBand

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        • #5
          Yes,please. I removed the grid stopper and now can put down volume pot without any issue at the end of track.It was a very low noise but still audible close to the end track pot position, The pot acted like a switch to a point and suspected is a pot fault, but keeping pot open and shunted the wiper to ground with a wire got the same result. Grid stopper gone and now no sign of issue.Thanks

          Not pretty sure if was ht ripple noise, but sound as same have no ideea how I get it
          Last edited by catalin gramada; 05-26-2019, 07:11 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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