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What Happens if my 21H runs on 1 Power Amp

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  • What Happens if my 21H runs on 1 Power Amp

    What Happens if my 21H runs on 1 Power Tube. Found of my 5U4GB not working, organ powers up and plays. Does this cause the organ to sound "weak/flat?"

  • #2
    The 5U4 is a rectifier. Two of them share the load of the B+ supply, which is why the amplifier still works with one tube out. But the other 5U4 will be stressed, and the power transformer and reservoir capacitors too since there will only be half-wave rectification. There The B+ may 'sag' at full volume and deprive the amplifier of power. I would avoid using the amplifier until you have two working 5U4s in position.

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    • #3
      The way the 5U4s are wired in the 32H amp is that each one is wired as a single diode. With one missing, you no longer have a full-wave rectifier circuit, just a half-wave rectifier. This will cause the B+ voltage to drop significantly. And, as Lucien says above, it increases the load on the remaining 5U4, so I would replace the missing tube ASAP.

      5U4s are very common tubes, so there should be no trouble finding a replacement.
      I'm David. 'Dave' is someone else's name.

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      • #4
        Originally posted by David Anderson View Post
        The way the 5U4s are wired in the 32H amp is that each one is wired as a single diode. With one missing, you no longer have a full-wave rectifier circuit, just a half-wave rectifier. This will cause the B+ voltage to drop significantly. And, as Lucien says above, it increases the load on the remaining 5U4, so I would replace the missing tube ASAP.

        5U4s are very common tubes, so there should be no trouble finding a replacement.
        David does this mean that the organ would sound weak? i really dont understand how it would affect the organs output....what does this translate to "you no longer have a full-wave rectifier circuit, just a half-wave rectifier. This will cause the B+ voltage to drop significantly" @Lucian Nunes @David Anderson

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        • #5
          This will also cause a higher ripple at 60Hz whereas with 2 tubes, it was at 120Hz.

          This will affect loud bass.
          Higher ripple > More distorsion.
          120Hz > Not the same distortion.
          and finally not the same sound.

          Tx

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          • #6
            Originally posted by Jyvoipabo View Post
            This will also cause a higher ripple at 60Hz whereas with 2 tubes, it was at 120Hz.

            This will affect loud bass.
            Higher ripple > More distorsion.
            120Hz > Not the same distortion.
            and finally not the same sound.

            Tx
            Thanks Guys, will get me some on TWG.

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