Suspected Tube Out In PV11 Or Could It Be Another Culprit?

Discussion in 'Audio Hardware' started by Gregory Earl, Nov 8, 2018.

  1. Gregory Earl

    Gregory Earl Forum Resident Thread Starter

    I was listening to my tuner last weekend and suddenly there was a weird kind of time warp distorted sound that started coming from both channels. Reminded me of the time a tube went out in my old Rogue amp.

    I rushed over to my amp and turned it off. When I powered it up again and played the tuner I got distorted sound from both channels. Bad distortion. I then tried different sources and got the same thing. I suspect a bad tube in the PV-11 since my amp is the solid-state Conrad Johnson MF-2200.

    Thing is all the tubes in the pre-amp still glow. Am I wrong in thinking it's a tube? Could it be a capacitor? What should I look for here?

    Thanks in advance for all replies.
  2. BIGGER Dave

    BIGGER Dave Forum Resident

    I'm having a hard time finding a schematic on the web for the PV11. Do you have a schematic you can post? Also, is this the tube complement:

    V1 - 12AX7
    V2 - 12AX7
    V3 - 5751
    V4- 12AU7
    V5 - 12AU7
    V6 - 12AU7

    If so, these are all fairly common tubes and a quick swap for known good tubes could identify the issue rather quickly (if it's a tube issue). I would get a good 12AX7/ecc83, a 5751 and a 12AU7/ecc82, and then swap ONE tube at a time. If the noise goes away, then the problem is with the tube you just replaced.
  3. Davey

    Davey very clever with maracas

    SF Bay Area, USA
  4. KT88

    KT88 Forum Resident

    The only thing that you can do as far as troubleshooting without either testing or substituting all of the tubes is to remove and reinstall all of the tubes. That should help with any connectivity issues. If that doesn't help, then swapping the power amp and the preamp with other units could reveal which amp is misbehaving. It could very well be the power amp.

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