Home › Forums › Help/Technical Questions › Wiggler distortion – bad tube?

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  • April 2, 2010 at 3:25 am #80117
    kayjay
    Member

    I just bought a Wiggler (tube trem pedal) used, and when it arrived, I noticed that the sound was very distorted, and I had to crank the Volume. Even with Intensity backed off completely, so I could A/B the bypassed and effected signals, the signal was very distorted…

    Acting on a hunch, I switched the tubes (putting each in the other position). After doing so, the gain was much louder, and the signal was distortion-free, however the signal was very trebly and bass-weak, like it was being passed through a high-pass filter…

    Sounds like one of the tubes is bad, no?

    Anyone know how I can tell which one is bad?

    Thanks in advance…

    April 2, 2010 at 3:34 am #108979
    Fender&EHX4ever
    Moderator

    I use this simple tube tester just to test for shorts and emissions. I bought it on eBay for about $40.

    If you use a lot of gear with tubes in it (like me), it’s worth the investment.

    accurate151.jpg

    April 2, 2010 at 4:01 am #108980
    kayjay
    Member

    So there’s no way to tell which tube is bad from the description of the effects of swapping the tubes? Like maybe one of the tubes is responsible for the drive circuitry, and one for some filtering, perhaps?

    I’ve downloaded the schematics, but, erm, well, it’s been a long time since I took that electronics course in college, and, well… :-/

    April 2, 2010 at 4:44 am #108981
    kayjay
    Member

    Oh, and one other question: is there a suitable replacement tube other than the 12AX7WB? Some other member of the 12AX7 family, or perhaps a 5751? Is there some reason I should steer clear of other tubes, other than the stock 12AX7WB?

    Thanks!

    April 2, 2010 at 4:50 am #108984
    Toonster
    Member

    Well I read about a lot of people changing the tubes to other kinds, as long as they fit in to the socket of course^^
    But I don’t exactly know the effects with that on a trem pedal, they all had EHX tube overdrives/distortions..

    April 2, 2010 at 10:29 am #108986
    The EH Man
    Moderator

    You’ll need to substitute the tubes one at a time with another 12AX7. You can also try the 5751, 12AT7, or 12AU7. You’ve probably got a tube you can pull from an amp for testing purposes.

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