Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Problems with AC hum, from effects

Discussion in 'Amps and Cabs [BG]' started by Gerard Rizzardo, Nov 6, 2000.


  1. Has anyone got any suggestions how I can try to lower or eliminate the AC hum, which is quite loud that I get from my amp, when I have my effects racks plugged through (ie send & recieve) ??
     
  2. Christopher

    Christopher

    Apr 28, 2000
    New York, NY
    How many effects are you running through the amp? The more components you have, the greater your susceptibility to picking up AC and RF interference. I'd try each of your effects and cables one by one to see if a particular component is the culprit. Use quality shielded cables and ferrite beads where possible. Make sure your effects are grounded (or are plugged into a power strip/conditioner that doesn't bypass ground). As a last resort, you can purchase an electronic noise gate. Good luck.
     
  3. Thanks greatly for your advice, Chris !!!
     
  4. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    If you're using wall wart power supplies for the effects, use high quality ones. My brother switched from Radio Shack hummers to Boss power supplies, and the hum went away. The shielded cable recommendation is a good one, too.
     
  5. MikeyD

    MikeyD

    Sep 9, 2000
    You may also be getting a "ground loop", which results from having two different paths to ground. For example, there may be a path from your amp chassis to ground via its power cord, and another path from your effects equipment chassis to ground via their power cord(s). When you plug in the signal cables, the shields in the cables connect the grounded chassis of the amp to that of the effects. This creates a ground loop, and can introduce power line hum into the system. You may be able to mitigate it by lifting the grounded shield at ONE end (only) of the signal cables. You also might try "bonding" the two chassis together with a very heavy gauge grounding strap, so that the slight voltage differential between them might be equalized. There may be some other ways to deal with this often difficult problem. (However, do NOT break off the ground terminals of your equipment's power cords or otherwise circumvent proper grounding - you could be electrocuted if something goes wrong!)
    - Mike