Birds in my Rocker 30H, bad tube?

Discussion in 'Amps and Cabs' started by kodax, May 24, 2008.

  1. kodax

    kodax Member

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    I just replaced the two power tubes in my Orange Rocker 30H from the stock chinese EL84 to JJ E84L.
    When I turned the gain channel up, it sounded like there was a kind of bird whisteling when I wasn't playing. (Don't think there was anything on the clean channel.) I haven't tried the tapping test to check for microphinics, but is that a likely cause? (I don't have the amp here at home, so I can't test out things right now.
     
  2. hamfist

    hamfist Member

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    Firstly I suspect you have put in El34's, as that's what the amp takes (yes it's a common typo !).
    Sounds very much like a microphonic tube to me. If you have the old EL34's still, then put them back in and see if the noises stop. If they do, then you have identified the problem. If the noises don't stop, then it's almost certainly a pre-amp tube - probably the 12AX7 in V1 (the nearest tube to the guitar input jack).
     
  3. kodax

    kodax Member

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    Correct, I replaced the EL43 with E34L, (and not 84).
     
  4. guitarded_1

    guitarded_1 Supporting Member

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    You're getting warmer!
     
  5. kodax

    kodax Member

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    Haha, this was hard: EL34 with E34L (and now it's right:)
     
  6. guitarded_1

    guitarded_1 Supporting Member

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    No worries. That definitely sounds like a tube related issue, though I commonly hear those noises from bad preamp tubes. About the tap test - I find it to be fairly useless, unless a tube is insanely microphonic. I just try to narrow it down and eliminate the bad tube(s) by swapping them out for good ones. I agree with hamfist - swap out the power tubes first and see if that does the trick. If not, start swapping out preamp tubes one at a time.
     
  7. kodax

    kodax Member

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    Tried the amp again yesterday, and now the weird sound was gone.
    Is this something that might happen with new tubes before they "settle" maby?
     

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