My amp is driving me crazy by picking up AM Radio. Any help appreciated!

Discussion in 'Amps and Cabs [BG]' started by JPOT, Mar 10, 2022.

  1. JPOT

    JPOT

    Jan 21, 2022
    Hi everyone!

    Last weekend, I bought (used) a GK MB200 head and CX210 cab. I tried them out first and they sounded so great. I was staying with a friend at the time, so I set them up at his place and played bass all weekend and it sounded wonderful. However, now that I've brought them home to my own house, I'm having a really annoying and distracting problem with always hearing AM radio through the amp while I'm playing!

    I've done some troubleshooting. I tried every combination of equipment I own and what I've noticed is this:
    - the head & cab are completely silent on their own with nothing plugged in.
    - as soon as I plug a cable in, I can faintly hear the radio. Some cables are better/worse than others.
    - when I plug my bass in, that's when the radio gets really loud and distracting. It's worse when I touch the strings. Even with one of the "better" cables from the previous step, the noise gets extremely distracting at this point.
    - putting any pedals in the chain definitely makes it worse.
    - my other amp (my tiny Fender Rumble 15w) very occasionally also picked up AM radio, but it was always very faint - never at this annoying and distracting level.
    - I tried moving all over the house with the amp to see if I could find a better spot, try different outlets, etc, but it was mostly even worse than the corner of my living room where I usually play.

    So, I think I have to conclude that the GK is just more sensitive to this that the Rumble, but ultimately it seems most of the noise is coming from my bass. I did already (long before this) take it all apart and shield all cavities thoroughly with copper tape. It has DiMarzio Model P/J pickups, if that helps. I did not take apart the pickups and shield inside their plastic covers because it seemed they were fairly solidly in there, maybe glued? I'm not sure, but I didn't want to mess with them.

    So, my question is this: what can I do about this? Would really expensive cables help, or more likely not since the noise seems to be mostly coming from my bass? Would shielding inside the pickup covers help (and has anyone done this with DiMarzio's - are they easy to get into?) I'm really feeling bummed that currently I can't really use my lovely new amp in my own house.

    Thanks for any help!
    JPOT
     
  2. Lovep

    Lovep Supporting Member

    Mar 17, 2011
    Indianapolis, IN
    Do you have an old house? What is your power supply?
     
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  3. JPOT

    JPOT

    Jan 21, 2022
    Hi Lovep! Yeah, probably should have mentioned that. The house is, I think, about 30 years old. I am renting, so I'm not at liberty to change anything about the wiring. It's just regular municipal power grid, nothing weird or special.
     
  4. First thing I would check is the ground on your power cord for the amp. Remove all your pedals and outboard gear and plug the bass directly into the amp input to simplify troubleshooting. Because your amp exhibits the same problem at various locations in your home, the problem is either a grounding issue with your amp, or the entire ground system in your home. How old is the house?

    Edit: I see the house is 30 years old. It might be worth getting an electrician in to check the electrical grounding in the house; there may be serious safety issues happening.
     
  5. JPOT

    JPOT

    Jan 21, 2022
    I have a multi-meter and checked that there is continuity from the ground on my bass through to the ground on the amp's power plug. That seemed fine. Is there anything else I can/should check on my own before involving an electrician?
     
  6. SwitchGear

    SwitchGear Supporting Member

    Mar 23, 2005
    Sunny Beach
    If Paul Harvey was still around you would be wished a “good day” through your amp
     
  7. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Had a Hartke 3500 do the same thing. IIRC, a strong attenuation at 1k virtually eliminated it...it was an outdoor gig.

    I hope the OP responds soon as I want to hear...the rest of the story.

    Riis
     
  8. JPOT

    JPOT

    Jan 21, 2022
    I am the OP and there's no more to the story... yet. I am hoping I can resolve this somehow!

    What does "strong attenuation at 1k" mean?
     
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  9. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Paul Harvey...maybe before your time.

    On me GEQ, I pulled the 1k slider waaaaay down. May or may not work. You can also attempt via a PEQ.

    Riis
     
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  10. JPOT

    JPOT

    Jan 21, 2022
    Yeah, I've only barely heard of Paul Harvey, but I did get the gist. It is definitely kinda funny hearing radio through the amp! Last night they had a comedian on. :D I did some googling and found out that the transmitter for this station is about 4.4km away from me, and it's a 50,000 W tower!

    So, you're talking about the EQ settings? On the GK, there are 4: treble, hi-mid, low-mid, and bass. If I turn the hi-mid down to 0 it definitely cuts this radio noise, and if I tweek the treble a bit as well, I can pretty much get rid of it. I thought that might be a good enough solution, but when I started to play... nah. My bass sounded all dull and thumpy then, not the big round sound that I loved so much when I bought the amp. So that's a no-go as a permanent solution.
     
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  11. ddnidd1

    ddnidd1 Supporting Member

    You an install a choke internally near the input of the amp or add a very small capacitor at the input to shunt just the radio frequencies to ground.
     
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  12. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Grab some cartons and move.

    My experience happened outside, adjacent to a waterway. Began picking up Radio Free Europe or the Japanese Imperial Navy. Best I could do on-the-fly was as described. Something is acting as an antennae.

    Riis
     
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  13. basscooker

    basscooker Commercial User

    Apr 11, 2010
    Northern KY
    Cab fan, hobbyist
    faraday_350px.jpg
     
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  14. dougjwray

    dougjwray

    Jul 20, 2005
    When I was in college, my band practiced at night in our off-campus apartment, a second-floor flat over a dentist's office. We were always a little paranoid about it-- loud music, some illicit ingesting of various substances, etc.
    One night a voice abruptly blared through my amp:"OKAY! OPEN THE DOOR!!"
    After our heart rates returned to normal, we realized that it was coming from a CB radio in a vehicle in the street outside. CBs were a fad then, and "open the door" was lingo for something. :dead:
     
  15. darwin-bass

    darwin-bass Supporting Member

    Mar 29, 2013
    Salem OR
    Do you get RFI with both pickups on? Neck solo? Bridge solo? Is there a preamp in the bass or is it passive?
     
  16. darwin-bass

    darwin-bass Supporting Member

    Mar 29, 2013
    Salem OR
    How close is the radio station antenna?
     
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  17. JPOT

    JPOT

    Jan 21, 2022
    The bass is passive, and I hear the radio with both pickups on or either soloed, no difference.
     
  18. JPOT

    JPOT

    Jan 21, 2022
    4.4km away, 50,000 W.
     
  19. Rojd

    Rojd Supporting Member

    May 29, 2018
    Rocky Mountains
    In my experience I bought a new pedal for my board and immediately started getting a Spanish radio station throught my cab. No matter what I did, I couldn't get rid of the station. I ended up getting rid of the pedal. That solved it.
     
  20. IBJammin

    IBJammin

    Apr 16, 2015
    Are you sure you are using an instrument cable from your bass? Not a speaker cable.
     
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