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Ac30 CC2 Static Problem

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  • 03-11-2010 9:53pm
    #1
    RileyH
    Closed Accounts Posts: 3 ✭


    I recently purchased second hand ac30cc2. This problem semms to be getting worse and worse and is most identifieable on a clean amp setting. When ever i hit a certain chord or not and let it hang there seems to be an almost static like noise coming through the speakers. It doesnt interupt the note but seems to come in behind it. It will stay there and then fade off. Once in a while it seems to go away but is usually there. It is also barly noticeable when using higher gain(tube screamer). It happens on all guitars. Could it be the pots possibly being dirty?, i can notice a very faint scratchy sound on the master volume, or posibly something to do with the tubes? Hopefully it is an easy fix i could do my self. I really love the tone of the amp so any help to make this go away would be greatly appreciated. Thanks
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    #2
    Paolo_M
    Registered Users Posts: 880 ✭✭✭Paolo_M


    In most cases this problem is preamp valve related.
    Do you have a buddy with a valve amp that's working well who'd let you borrow some 12AX7 (ECC83) valves, I think you'll need three for that AC30?
    It's also possible that the power valves, EL84s, are causing the problem but preamp valves are more common so check them first.

    Scratchy pots can be cleaned with electrical contact cleaner, however it's not always easy to get at them. How would you be with dismantling the amp and taking out the chassis, and potentially the PCB?
    Scratchy pots can also be caused by leaky capacitors, however this usually produces a really grating, hard scratching.


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    #3
    RileyH
    Closed Accounts Posts: 3 ✭RileyH


    thanks for the reply, just tried taking it apart, finally got the back cover off after a long battle and a few stripped bolt, , they are in so dam tight could hardly move, and strip so easy, i have a fender blues jr that ill try a couple of the preamp tubes out of, how do i know what socket to put the new tube in? the ac30 is self biasing right? Thanks


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    #4
    ball ox
    Registered Users Posts: 699 ✭✭✭ball ox


    I had an ac30 once which started making a noise exactly like what you have described. A complete re-tube sorted it out. Not sure which tube it was but, as Paolo_M has said, most likely the pre-amp. Certainly worth a complete re-tube though if the current tubes are stock. Made a big difference for me anyway.


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