My bass was picking up radio signal

Discussion in 'Pickups & Electronics [BG]' started by jakelly, Dec 28, 2013.

  1. jakelly


    Nov 8, 2009
    It has virtually no shielding and I know it needs it, but how exactly does it pick up radio signals? Through the pickup? Controls & wiring? Or all of the above?
  2. P Town

    P Town

    Dec 7, 2011
    It could be the guitar, or the amp. Most likely you are picking up an AM station. AM stands for amplitude modulation. The way it works is that the broadcasting station modulates the amplitude of a carrier frequency, by the audio program material. The receiver translates the modulated signal by demodulating the signal. The most basic circuit to demodulate an AM signal is a diode. A diode can exist as a simple contact point between two conductors. This is known as a "cat's whisker" diode. After you determine that it is the guitar, inspect the circuitry, move anything that looks like it is very close to anything else, so as to make a very slight contact. Shielding may help if the source of the rectification is in a component that you can not alter by re-arranging the wiring.
    I played in a band with a guy back in the early 1970s, whos Silvertone amp would pick up AM radio signals only when we played a certain bar. I fiddled around with the thing, and moved stuff, as I was looking at the internal wiring, and by the simple act of moving the wires, it quit reproducing AM radio signals while we were on break at the gig. I can't say what I did actually fixed the problem. It could have been caused by how he leaned his Silvertone guitar against the amp as well.
    Good luck.