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What Happens if my 21H runs on 1 Power Amp

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  • TriniCV
    ppp Pianississmo
    • Mar 2011
    • 31

    #1

    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?"
  • Lucien Nunes
    Deceased
    • Dec 2008
    • 231
    • London UK

    #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.

    Comment

    • David Anderson
      fff Fortississimo
      • Apr 2011
      • 6214

      #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.

      Comment

      • TriniCV
        ppp Pianississmo
        • Mar 2011
        • 31

        #4
        Originally posted by David Anderson
        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

        Comment

        • Jyvoipabo
          ff Fortissimo
          • Nov 2016
          • 1033
          • South Groland

          #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

          Comment

          • TriniCV
            ppp Pianississmo
            • Mar 2011
            • 31

            #6
            Originally posted by Jyvoipabo
            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.

            Comment

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