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Thread: Trouble with Conrad Johnson PV12A

  1. #1
    Join Date: Aug 2010

    Location: Bergerac, France

    Posts: 567
    I'm Francois.

    Unhappy Trouble with Conrad Johnson PV12A

    Morning all,

    Recently I acquired a Conrad Johnson PV12A (the one with phono stage). The unit is around 11 years of age.
    All good until recently.
    It started popping and hissing and 'spurting' on one channel... The 'funny noises' were not affected by volume though! Always the same pretty much...
    First instinct was that the tubes or one tube was on its way out.
    Swapped them for new ones (Mullard NOS 12au7), and to my surprise the 'funny' noises had swapped sides, now coming from the opposite channel !?!

    I am a bit confused really...

    So does anyone has a clue of what is happening...
    And also any recommendations as to who to contact re: Servicing a tube preamp in the London area?

    Many thanks

    looking forward reading your answers!

    F
    Francois, Bergerac, France
    Source component/s:
    Musical Fidelity M1 Dac, Allo Digi One, Sony SCD-XE800, AVID Ingenium Twin arm, Audio Note Arm One, Groovemaster II 12in, Audio Note IQ3 MM, Denon DL103R MC, Croft Basic 25, TQ Iridium Phonostage, Puresound T10 Stepup Transformer, Zavfino majestic tonearm cable
    Amplification:
    Audio Note OTO PP, Dussun V6i
    Loudspeakers:
    Triangle Comete ES, Klispch RP600M
    Cables/stands:
    Quadraspire, Belden 9497

  2. #2
    Join Date: Nov 2008

    Location: Valley of the Hazels

    Posts: 9,139
    I'm AMusicFanNotAnAudiophile.

    Default

    Have you swapped the new ones around, and did the problem move ?
    If you haven't, do so, and see what happens.
    You may have replaced a good valve with a duff one.
    Chris



    Common sense isn't anymore!

  3. #3
    Join Date: Aug 2010

    Location: Bergerac, France

    Posts: 567
    I'm Francois.

    Default

    Yes, i have indeed.
    I replaced the the tubes involved in the preamp section and swapped them around twice.
    As the problem occurs on both Cd and TT... I left the phono section alone and untouched.
    Francois, Bergerac, France
    Source component/s:
    Musical Fidelity M1 Dac, Allo Digi One, Sony SCD-XE800, AVID Ingenium Twin arm, Audio Note Arm One, Groovemaster II 12in, Audio Note IQ3 MM, Denon DL103R MC, Croft Basic 25, TQ Iridium Phonostage, Puresound T10 Stepup Transformer, Zavfino majestic tonearm cable
    Amplification:
    Audio Note OTO PP, Dussun V6i
    Loudspeakers:
    Triangle Comete ES, Klispch RP600M
    Cables/stands:
    Quadraspire, Belden 9497

  4. #4
    Join Date: Mar 2008

    Location: Galashiels

    Posts: 13,669
    I'm inthescottishmafia.

    Default

    Join the WD forum and you can ask John Caswell to have a look at it. He lives in Wokingham. He does the repairs and builds for WD,or at least he used to until they were sold. He's a nice chap and very k.owledeable. He'll sort it.

  5. #5
    Join Date: Jan 2009

    Location: Deleted

    Posts: 6,585
    I'm Deleted.

    Default

    It could well be that some capacitors need replacing - valves do like to cook them a bit and this seems to shorten their life span.
    Last edited by YNWaN; 23-10-2010 at 10:17.
    Account Deleted

  6. #6
    Join Date: Mar 2008

    Location: Galashiels

    Posts: 13,669
    I'm inthescottishmafia.

    Default

    Yes indeed,a common occurence with valve amps,especially ones of this age.

  7. #7
    Join Date: Aug 2010

    Location: Bergerac, France

    Posts: 567
    I'm Francois.

    Default

    Quote Originally Posted by Ali Tait View Post
    Join the WD forum and you can ask John Caswell to have a look at it. He lives in Wokingham. He does the repairs and builds for WD,or at least he used to until they were sold. He's a nice chap and very k.owledeable. He'll sort it.
    Thanks, when you say WD, you mean Western Digital?
    excuse my ignorance...
    Francois, Bergerac, France
    Source component/s:
    Musical Fidelity M1 Dac, Allo Digi One, Sony SCD-XE800, AVID Ingenium Twin arm, Audio Note Arm One, Groovemaster II 12in, Audio Note IQ3 MM, Denon DL103R MC, Croft Basic 25, TQ Iridium Phonostage, Puresound T10 Stepup Transformer, Zavfino majestic tonearm cable
    Amplification:
    Audio Note OTO PP, Dussun V6i
    Loudspeakers:
    Triangle Comete ES, Klispch RP600M
    Cables/stands:
    Quadraspire, Belden 9497

  8. #8
    Join Date: Nov 2008

    Location: Valley of the Hazels

    Posts: 9,139
    I'm AMusicFanNotAnAudiophile.

    Default

    Chris



    Common sense isn't anymore!

  9. #9
    Join Date: Aug 2010

    Location: Bergerac, France

    Posts: 567
    I'm Francois.

    Thumbs up

    Quote Originally Posted by Stratmangler View Post


    you see, I am pretty ignorant!

    Thanks a lot for the info!

    Cheers
    Francois, Bergerac, France
    Source component/s:
    Musical Fidelity M1 Dac, Allo Digi One, Sony SCD-XE800, AVID Ingenium Twin arm, Audio Note Arm One, Groovemaster II 12in, Audio Note IQ3 MM, Denon DL103R MC, Croft Basic 25, TQ Iridium Phonostage, Puresound T10 Stepup Transformer, Zavfino majestic tonearm cable
    Amplification:
    Audio Note OTO PP, Dussun V6i
    Loudspeakers:
    Triangle Comete ES, Klispch RP600M
    Cables/stands:
    Quadraspire, Belden 9497

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