Summoning Elite Troubleshooters

Discussion in 'Pickups & Electronics [BG]' started by Crosscheck67, Apr 11, 2021.

  1. Crosscheck67

    Crosscheck67

    Jan 18, 2020
    New to forum. Please advise if I'm misstepping.

    Symptom:

    I'm at wit's end trying to kill a 60 cycle hum in my bass I had built last summer. It's been there from day one. I've spent several months speaking with different manufacturers, all who have provided great support (EMG, Audient, Source Audio, Furman, etc). I arrive here as a last ditch effort. I'll spare you the entire history unless you ask for it. Believe it or not, this is the distilled version.

    My bass is built around custom woods from Warmoth, 2TEK Bridge, and the electronics are as follows:

    EMG J5 Active Pickups (although they are technically single coil, EMG says they are hum cancelling)
    EMG BTC System Active Preamp
    Double battery box, 7/8" jack and copper shielding from Warmoth. I did not realize at the time that shielding isn't needed with EMG.
    Pig Hog braided patch cables.

    The hum presents itself whether I'm playing through my Auident iD44, EBS Magni 500 2x10, Pedalboard with several Source Audio effects, or even just my Vox Amplug with headphones. It can be heard anywhere as I rotate in a 360 degree circle, save for two spots polar opposite of each other.

    The fact that this same thing happens with the little Amplug just screams environmental (Clue #1?)

    The bizarre thing is that it doesn't happen with my son's Ibanez FR700, or his Tobias Toby Deluxe IV, both active basses. What really kills me is that I went to a music room at the college my friend works at. We both plugged into my Audient, my bass hummed, and his Jazzmaster with passive single coils was quiet. What? How? (Clue #2?)

    The point of this bass was to be a nicer version of the one Mike Lull (RIP) built for me in the 90s, which has since been stolen. Granted that was 25 years ago and electronics were American built. I'm now in a small New England town which is extremely crowded with old, crappy infrastructure compared to Seattle. Bad power could be cooking the air.

    I took it to my luthier who built it. He tried rewiring the electronics, changed signal chain order, tried wiring the batteries both in serial and parallel, no difference. The one time we were able to have it quiet was plugged into an old giant Fender head and cab from the 60s (Clue #3?)

    Before I had tested with the Vox Amplug, I bought a Furman PL-Plus DMC. No difference. The lion's share of troubleshooting has been with EMG:

    They had me test each pickup independently, bypassing the Blend and BTC, No difference.
    They had me change the signal chain order, no difference.
    They had me rip out the shielding, no difference.
    They had me send all the electronics, jack, battery box and patch cable I was using and they threw them on their bench. No hum. (Clue #4?)
    They sent everything back along with some extra shielded coaxial cables and asked me to ground to the 2TEK Bridge, no difference.

    I then visited a highly recommended electronics and amp wizard who's been running a shop with his luthier for 25 years. The noise did not significantly present itself at their shop, either in their amp or in my Amplug (yes, I brought it along). So we reached the conclusion that it is truly environmental. They also explained that the shielding was doing nothing, as it wasn't grounded.

    SO. I ordered more shielding from Warmoth, took everything out, re-shielded the control & battery box cavities, and reinstalled everything. As EMG is mostly solderless, I can easily connect/disconnect the bridge ground. I also grounded the jack to the shielding. It sounds slightly better with the bridge ground disconnected, yet the hum still remains.

    The conclusion I've sort of reached is that for whatever reason, my setup is highly sensitive. Yet I don't understand how I haven't found a way to shield it from the alleged environmental noise, and how - in the same environment - my son's low and midrange basses are quiet, as is my friend's Jazzmaster. This was supposed to be my dream bass. I've moved well past anger and am now just quietly defeated :(

    Thanks to anyone who spends time on this thread.
     
  2. dwizum

    dwizum

    Dec 21, 2018
    How about some photos?

    What parts are/were shielded?
     
  3. Jeff Hughes

    Jeff Hughes

    May 3, 2020
    Have you tried the bass with different pickups? Is it possible the sound is environmental and exacerbated by the EMGs?
     
    fig likes this.
  4. Jerry C

    Jerry C Guest Commercial User

    Apr 9, 2021
    Montreal
    Copper or aluminum shielding does pretty much nothing against strong electromagnetic fields, such as those generated by power transformers. It only shields against electrostatic fields by creating a Faraday cage. To shield against electromagnetic fields, you'd have to use a ferromagnetic material such as mild steel or mu metal. Those pickup covers on old Jazz basses did just that.
    A passive bass with two singles can be very quiet if both pickups are on and they have opposite magnetic and electric polarity from each other, which will effectively make them into a humbucker. I bet your EMGs are the same polarity, so they can't work together to reduce hum, and I also bet that they're not nearly as immune to hum as EMG says, while you certainly have an environmental problem. Try to turn off anything with a transformer in it anywhere near the bass (say, within a 5-yard radius sphere - including lower and upper floor) while using your AmPlug. The hum should go away.
     
    Thrakkar, bdplaid and fig like this.
  5. dwizum

    dwizum

    Dec 21, 2018
    With an Amplug, "envrionmental" in the sense of 60 cycle hum should be easy to check - walk out into a field or other place away from buildings, power lines, etc.!
     
    96tbird, JKos, ddnidd1 and 2 others like this.
  6. Man, you've jumped through some hoops with this problem. But we ain't gonna get our a**es kicked here at TalkBass, no siree. You've talked to the rest, now you're talkin' to the best! Ain't that right, gang!? Gang??

    ...

    Who let the crickets in?...

    Ok, cheerleading mode off LOL.

    I agree, something seems to be causing extra sensitivity to outside fields in that bass considering your son's basses are fine in the same locale. Testing in other locations seems to indicate it, too.

    Since you already bypassed the BTC with each pickup and the noise remained, are you convinced the pickups are the issue? Or are you not 100 percent sure and further troubleshooting to localize is still needed? I have a question about the BTC bypass you did, but will get to that in a bit.

    Do these two pdf's apply to your system? Seems right, just wanna be sure. I'm not familiar with EMG stuff, so this'd be helpful info to me and maybe some others playing the home game.

    https://www.emgpickups.com/pub/media/Mageants/b/t/btc_system_x_0230-0176rc.pdf
    https://www.emgpickups.com/pub/media/Mageants/j/5/j5_j5a_j5cs_set_0230-0252rb.pdf
     
    Last edited: Apr 12, 2021
  7. micguy

    micguy

    May 17, 2011
    That statement by itself tells you what you need to know. Your situation isn't at all complex. It is (I ended up in pretty much the same boat recently) disappointing, however.

    You may think you have a hum cancelling pickup, but you don't. What you describe (2 directions in space opposite each other where there is no hum) is precisely what you get from a non - hum cancelling pickup in a magnetic hum field. There are situations (no hum field) where single coils are quiet (this may confuse you, but it is what it is). I (and many of us) prefer basses that work anywhere. By the way, shielding does NOT get rid of magnetic hum - it fixes electrostatic hum, which is a different animal.

    I recently bought a few pickups in anticipation of a build. One of them was a set of passive EMG J's - which are built in the same factory, and share the same construction magnetically as one of the active models (maybe the same as yours, maybe not). I hooked the various pickups up up and listened to them to evaluate hum before buying a second one to complete a set. Despite the EMG's being advertised as hum cancelling, they...didn't do that. I ended up using Seymour Duncan stacks that....actually cancel hum. You may want to do the same.

    FYI, 5 string inline cancelling pickups are...not perfectly hum cancelling in most cases - the odd number of strings causes an imbalance that's not easily solvable in the same form factor as a single coil. They are quieter than a single coil, but the hum doesn't completely go away - the coil covering 3 strings is bigger than the one covering 2, and 3-2 does not equal zero. Actual stacks work better if you need complete hum cancellation on a 5 string.
     
  8. NoiseNinja

    NoiseNinja Experimental-psychedelic-ambient-noise-drone Inactive

    Feb 23, 2011
    Denmark
    This is clearly a result of paranormal activity, if I were you I'd reach out to FBI's X-files team.
     
    jchrisk1 and fig like this.
  9. micguy

    micguy

    May 17, 2011
    This comment confuses me, for two reasons:

    1) I've been alive since the first Jazz bass was produced (OK, just barely), and I've never seen one with pickup covers made of ferrous (magnetically shielding) metal of any sort.

    2) If you successfully magnetically shielded a pickup from the outside world with steel or mu metal, you would also reduce its output to....zero. Yes it'd lack hum, but it'd also lack output. Am I missing something here?
     
  10. King Louie

    King Louie

    Jul 17, 2016
    Is it exactly 60 cycle hum, or only close? It may be a defective preamp that just happens to oscillate in a frequency close to 60Hz.

    If you think a Toby Deluxe is quiet in comparison, then it is bad. I ripped the preamp out of mine because of the noise (not 60 cycle though)
     
  11. dwizum

    dwizum

    Dec 21, 2018
    Aren't the original Fender ashtray style covers made from chrome plated stamped steel?
     
  12. Any dimmer switches where you are playing it? They really cause all my instruments to hum and I now replace them in every house I live in.
     
    Rabidhamster, bdplaid and dwizum like this.
  13. bdplaid

    bdplaid Supporting Member

    Aug 31, 2007
    Have you ever played the bass in another town with different results?
     
  14. 40Hz

    40Hz Supporting Member

    May 24, 2006
    home
    Do you have anything in the house that uses your walk wiring as a control signal source? Things like network devices that transmit over your AC wiring, smart home lighting controls or home security monitoring devices and similar modules? If so you might be picking up some control signals on your power line. If a neighbor is on the same leg of the pole transformer feeding your home it could also originate there.
     
  15. Jerry C

    Jerry C Guest Commercial User

    Apr 9, 2021
    Montreal
    1) I am talking about the pickup covers that go above the strings, so you don't even see the actual pickups. They're made of chrome plated steel.

    2) As in 1, the shield would have to go above the strings, or else you throw the baby with the bath water. No hum, and no signal :)
     
  16. Jerry C

    Jerry C Guest Commercial User

    Apr 9, 2021
    Montreal
    They are, and they're there specifically to shield standard single coils from magnetic fields where nothing else would work.
     
  17. mikecd1

    mikecd1

    Mar 3, 2009
    New England
    First of all, sorry to hear when a dream gets a tad ugly, but like fig said you've got some firepower here on TB and some mighty smart bassbrothers have helped me out in the past for my share of funky wiring problems, but never with EMG. Active pickups - the red wires from pups go to the battery boxes which are wired together I assume. Make sure none of the contacts of the battery boxes are touching your shielding. I'd also suggest a ground wire from the side of your pot(s) to the shielding. Not sure how the wires are routed, but you might need a wire from each pot to the shielding if the grounds don't connect all the pots together somehow. Usually EMG grounding works by grounding all the components to themselves, but if your bridge is grounded to the shielding and you ground your pots also to the shielding I don't see how this thing could hum. Keep us posted.
     
    Crosscheck67 and fig like this.
  18. I agree, the pickups are most likely the problem. As @micguy said, and @Crosscheck67 confirmed with his bass, there's two quiet zones opposite each other as he turns in a circle. It's acting as a directional antenna which use loops of wire as the sensing elements. And for whatever reason, it's more sensitive than his son's basses at home, or others basses at other locations.

    It'd be great to find the home source, but don't fix it yet. That interference is currently a beneficial test signal you can use until the bass is fixed and quiet, i.e., not picking up the "test signal" anymore. If you kill the interference now, you won't know if the bass ever gets fixed (other than testing it elsewhere).

    If it were me, I'd try pulling all circuit breakers in my house except the circuit the amp is using. That'd remove power on all dimmers, appliances, computers, TV's, etc, at once. On that remaining live circuit, turn off or unplug remaining items. If noise isn't there anymore, turn on one breaker, test bass, turn on another breaker, test bass, etc. When the noise occurs, the source is on that breaker circuit. Then go around and reset all electric clocks LOL. Like I said, you can find it, but don't fix it (if possible) yet as you need it for convenient bass testing purposes.
     
  19. micguy

    micguy

    May 17, 2011
    Sorry - mental block. I was envisioning iron covers on the pickups, not over the pickups. Yes, those help - some.
     
    dwizum likes this.
  20. el murdoque

    el murdoque

    Mar 10, 2013
    Germany
    How about introducing some real troubleshooting logic?

    Use only one pickup, wired straight to the output jack. What happens?
     
    Rabidhamster likes this.