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Amplifiers

Posted by Coppa Penny on September 6, 2013 at 3:38am in Building Secrets, Tips, Advice, Discussion

I know that this question has been asked and answered many times before. But have we come to a final answer. Is it shielding, better grounding or other. If it shielding , how is it done also with grounding. My amp hums on mains power but my small battery  is fine. Stops when I touch the jack.

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Replies

  • Jim Woods September 8, 2013 at 3:24pm

    I have found the Noisy Cricket (LM386) amps I build are sensitive to poorly regulated power supplies.  The symptoms are as you describe.  One fix is a power regulator such as LM317 to clean up the power

    • John Sawyer > Jim Woods September 9, 2013 at 11:30pm

      Or a capacitor (>470uf) across power and ground near the DC power input to the board...  This too sounds like a poorly regulated power supply...

  • The Phrygian Kid September 6, 2013 at 8:27am
    I'm tipping what you're hearing would much better be described as white noise (buzz) than a hum. If it is a hum then it might be anything from a bad power amp tube to sixty cycle hum from fleuro tube lights or other electrical interference. If its a buzz then look to shielding your circuit better. And definitely bridging your strings to ground so that touching the strings is same as touching the jack there. Inadequate shielding will often be interpreted as a 'grounding issue' By many folks so it's not necessarily an either/or position with this question. Try to be more descriptive or maybe make a short video. Does the amp buzz with all guitars or only this one?
  • Slowpaw Steve T September 6, 2013 at 7:17am

    If the hum stops when you touch the jack that would indicate a grounding issue, without the benefit of knowing your set up and wiring of the pickup in your guitar (-:

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