Hum mystery: I don't find the solution. Can anyone help me please?

Discussion in 'Pickups & Electronics [BG]' started by Syl_Funky_bass, Jun 27, 2020.

  1. Syl_Funky_bass


    Jun 4, 2016
    Hi guys,

    I need your help on something that's a real mystery to me:

    I've recently bought a new bass which I'm totally satisfied with. I really dig this instrument. It's a 2006 Fender Victor Bailey Jazz Bass V in mint condition.

    But I have a problem with it: I get a lot (really a lot!) of hum (not sure it's called hum but I think so) when I plug my bass to my amp.

    I made some research and I'm aware it's perfectly normal for single coils to produce some hum. But here it's a clearly abnormal and strong noise.

    The hum disappears as soon as I touch any metallic part of my bass (strings, pots, tuning machines etc...). According to my research this is typical of a shielding problem with the bass.

    As far as troubleshooting is concerned, here is what has been done so far:

    At home:

    -I tried my amp and cab with my other bass (2nd gen Sire V7 vintage 5) and don't get any abnormally high amount of hum at all.

    With the V Bailey Jazz:
    - I tried different brand new jack cables
    - A new power supply cable with my amp (brand new Markbass Little Ninja + Ninja 212 cab)
    - New high quality 9-volts batteries in my active bass.

    ... and still get that same abnormally high amount of hum.

    After that I brought the bass to a local guitar tech who put some new shielding to it. We tried the bass at his place with his amp and cab and it was perfectly fine. No abnormal hum at all.

    I got back home and tried it again and got the exact same hum issue.

    I then suspected grounding issues in my home (even though I have no problem at all with my other bass) so I took the V Bailey Jazz bass, my amp and cab to another location and tried them. I still get the same hum problem.

    Right after that I tried the bass again with another amp and cab that was present in the room and didn't get any hum at all.

    To sum it up: I get extremely high hum from my bass only with my (brand new) amp and cab (not with my other bass though).

    What should I do, guys? I'm hopeless.

    Thanks for your help in advance.
  2. RSBBass


    Jun 11, 2011
    I suspect the issue is the outlet your amp is plugged into. Also, do you have dimmer switches or florescent lights in your room?
    jkazam and champbassist like this.
  3. Syl_Funky_bass


    Jun 4, 2016
    Thanks for the quick reply, man.
    No dimmer switches or florescent lights in the room.

    I thought the outlet might be the cause but then why is the extreme hum persisting even at another location. And why don't I get excessive hum with my other bass?
    I'm really lost.
    Feel like I tried everything...
  4. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    The FIRST thing to verify is that the bridge is electrically bonded to the output jack's shield/sleeve terminal.

    Nothing else matters if this is not correct.
    DavC, MrLenny1, Zooberwerx and 2 others like this.
  5. Syl_Funky_bass


    Jun 4, 2016
    Thanks for the insight.
    The bass has just been re-shielded by a renowned luthier living in my area so I presumed it's one of the first things he checked.
    I'm still wondering why this abnormal hum only occurs with the combination of that specific bass and amp + cab.
    That same bass doesn't make any such hum with other amps and cabs.
    And the amp + cab in question work just fine with any other basses.
    Still a mystery...
  6. Raf Seibert

    Raf Seibert

    Dec 16, 2013
    Do you have a multimeter? If so, check the resistance between the sleeve connection of the output jack and the metal parts of the bridge as Agedhorse suggested. That measurement should be very small (low resistance).
    Syl_Funky_bass likes this.
  7. Geri O

    Geri O Endorsing Artist, Mike Lull Guitars and Basses Gold Supporting Member

    Sep 6, 2013
    Florence, MS
    Not related, but I’ve wondered if you ever poked around in other forums besides the amp pages...,
  8. I thought these basses came with noiseless pickups?
    Syl_Funky_bass likes this.
  9. Wasnex


    Dec 25, 2011
    Obviously yes, and I have also seen him in other online communities. For example he has recently visited BassChat and Harmony Central.
    Geri O likes this.
  10. Stumbo

    Stumbo Guest

    Feb 11, 2008
    How about returning the amp for a refund or replacement?

    You could try your cab with another amp and your amp with another cab.
    Syl_Funky_bass likes this.
  11. Wasnex


    Dec 25, 2011
    Have you tried the bass and amp at a different location?

    It's very possible that the problem is electromagnetic interference (EMI) caused by the electromagnetic field (EMF) produced by the amp. I have a fairly large collection of amps and the EMF varies from amp to amp. Some of the induce noise in even my active basses if I stand close to them.

    If I use a passive bass in my basement I get quite a bit of hum, even if I am not close to an amp. If I change the direction the bass is facing, the hum varies; so the problem is in the air.

    I believe LED lights are potential sources for EMI.
  12. JKos


    Oct 26, 2010
    Surprise, AZ
    @Syl_Funky_bass ,
    This is a good question for you.
    Does the hum change as you move the bass around?

    - John
    Wasnex likes this.
  13. Syl_Funky_bass


    Jun 4, 2016
    Hey, Thanks everyone for the great insight. I feel I'm moving forward.

    At the moment, after reading all your precious tips, I think the cause of the problem lies most probably in the amp or cab. I spoke again with the luthier who worked on my VB Jazz V and he confirmed to me that the electrical connection between the bridge and the output jack canal was verified.

    So at the moment I don't believe there is anything wrong with my bass.

    I will ride this afternoon to a music instruments shop that sells the same head (Little Ninja) as mine. I'll bring my bass, amp head and cab.
    I'll try all possible combinations until I get to know who's the culprit.

    Sending my amp back head back is at the moment an option I'm seriously considering.

    I keep you posted, guys.

    Thanks everyone!
    Stumbo likes this.
  14. Syl_Funky_bass


    Jun 4, 2016
    The hum stays the same no matter what direction I point the bass at or as I move in a room. I've just made the test again to the be sure.
    Stumbo likes this.
  15. Syl_Funky_bass


    Jun 4, 2016
    Yes, indeed.
  16. Syl_Funky_bass


    Jun 4, 2016
    As I said in my initial post, I brought my bass, amp and cab to another location yesterday and I got the exact same problem there.
    Today I'm going to a music instruments shop with my gear to test different combinations there, including with another exemplary of my amp head.
    Wasnex likes this.
  17. JKos


    Oct 26, 2010
    Surprise, AZ
    That's important information and should help direct the ideas of what the cause could be.

    - John
  18. Another useful test would be to insert a pedal between the bass and the amp and see if that changes anything.
    Syl_Funky_bass and Stumbo like this.
  19. Syl_Funky_bass


    Jun 4, 2016
    Tried it with and without the my pedalboard. Same negative result.
    I'll be able to run multiple tests with various amps here in the shop in the Netherlands in about an hour.

    Keep you posted.
    Wasnex likes this.
  20. bbh

    bbh Supporting Member

    Sep 27, 2011
    I once had an issue like that. Turned out a wire was poking the battery case. Once that was determined that was the cause, a little bending and snipping the offending Wire end fixed the issue.
    Syl_Funky_bass likes this.