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  #1  
Old 09-17-2020, 02:27 AM
Kenny202 Kenny202 is offline
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Default Cole Clark pre amp background hiss

Just recently got a 2nd hand Cole Clark Fat lady 2. It's a 2011 model and has the old style 2 way pick up / preamp.

One thing is really annoying me is a back ground hiss. Sort of more noticeable when I turn the gain up past half. None of the other controls seem to effect it either way ie biasing / blender towards either pick up.

I contacted Cole Clark and got a really detailed and helpful email back. Initially the hiss was a lot worse and they suggested a new battery which did help the hiss and crackling immensely. A lot better now but still there. I have pulled the pre amp out. Plugged unplugged the pick up connections many times in case corroded. Touched up the battery contacts with a light sanding. Anyway after all that the hiss still there. Not serious but enough to be annoying. I've tried three leads. New Alkaline battery etc.

I am in a fairly remote area and wondering if someone could give me any pointers or somewhere to look? Maybe its inherent with this pre amp?
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Old 09-17-2020, 02:56 AM
mirwa mirwa is offline
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Its not an inherent problem, however if its at the stage where corrosion existed on the battery connections and pickup then its likely corrosion also exists internally on the circuit board.

Cole clarke do an exchange unit, that is you send them your unit and they will send you back a new one "costed" of course

Steve
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  #3  
Old 09-17-2020, 03:21 AM
Kenny202 Kenny202 is offline
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Quote:
Originally Posted by mirwa View Post
Its not an inherent problem, however if its at the stage where corrosion existed on the battery connections and pickup then its likely corrosion also exists internally on the circuit board.

Cole clarke do an exchange unit, that is you send them your unit and they will send you back a new one "costed" of course

Steve
Thanks for your reply. No, the battery terminals weren't anything approaching corroded. Cole Clark actually told me to return it to them replacement cost $120 which is more than fair. Only problem for me I live in Thailand and the post out probably ok, but can get all sorts of issues on the way back. First one customs. You can mark an item repair, gift etc but they will still hit you up for ridiculous taxes that are sometimes more than the item, and their is no debating it. Second problem the post itself is unreliable and items go missing. So for me this is a last resort. I don't suppose there is some way of knowing if the hiss is coming from the pre amp or the actually piezo / strip pick up. Unless I unplug them from the pre amp (1/8 jacks) and see if preamp still hisses with volume up.

Nothing else I could try? I don't suppose dabbing contact cleaner around a good idea
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Old 09-17-2020, 05:20 AM
jonfields45 jonfields45 is online now
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Could you put a picture of the PCB? If it is sufficiently simple you might try replacing the resistors with low noise metal film.
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Old 09-17-2020, 09:47 PM
Kenny202 Kenny202 is offline
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The PCB is in a sealed box which I possibly could open but I wouldn't be changing resistors etc. Would it be possible the PCB board is just dusty or something? Without removing / replacing components would it be worth cleaning it a bit maybe?
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Old 09-17-2020, 10:58 PM
mirwa mirwa is offline
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Its actually a 2 layer circuit board that unless you had an Oscilloscope and circuit diagram you could not troubleshoot.
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  #7  
Old 09-18-2020, 12:21 PM
Earl49 Earl49 is offline
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Quote:
Originally Posted by Kenny202 View Post
.....Unless I unplug them from the pre amp (1/8 jacks) and see if pre-amp still hisses with volume up.
That sounds like a good trouble shooting step to me. Anything you can do to isolate the problem is forward progress. Too bad that simply sending the pre-amp back for repair/replacement is such a pain.....
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