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Constant High Freq driving me nuts....

Discussion in 'Pickups & Electronics [BG]' started by Hoffman6000, Jun 25, 2011.

  1. I've done a search of TB and can't find any other posts about this so I'm starting one to try to solve my problem.

    I have a Fender Custom classic Jazz with Noiseless pickups that is giving me a faint yet constant high frequency buzz (around 8K). It goes away when I turn the bass' volume off, so I'm assuming its the pickups. I initially boiled it down to the single coils... then I debunked my theory with my G&L L2K as it was still there, in all wiring options and pickup selections. The sound is like a hearing test.

    if it helps here is my chain....Bass---25' of Canare cable---a loopmaster A/B/Y Box----George L Cable----FEA Labs Opti-Fet Compressor---- Red Eye DI---straight to the Digidesign SC48 Console---back to me through Senheiser IEM and Westone In-Ears. ALL of our gear is powered by the mamaJama Monster Power Pro AVS 2000 with 3 stage noise filtering to prevent any of this sort of thing.

    This sound doesn't happen in all places. Just some clubs, casinos, etc.
    I'm less interested in a simple solution such as an Isolated transformer or Hum canceling pedal and more interested in the technical aspect of what actually causes this. And why is the noise sneaking by the AVS 2000? Thanks for any help
  2. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    Those aren't single coils, because they are the noiseless models. They are stacked humbuckers.

    Is the high pitched noise a buzzing or sizzling type of sound?

    That's electrostatic interference and can be eliminated for the most part with better shielding.

    But in some clubs they have bad wiring and/or light dimmers, and then it's very difficult to get rid of. The pickups themselves are likely not internally shielded at all, which doesn't help. And even with totally shielded pickups, I've gotten some buzzing picked up in certain clubs that had many light dimmers.
  3. Thanks for your reply David,

    The sound is almost like a ringing in the ears sound. Not a buzz at all, just a clear fixed pitch like a very high sine wave. It does get a little faint when I turn in a certain direction, but it doesn't sound anything like 60 cycle hum. The bass cavity is shielded pretty well, but the pickups themselves are not....

    Could it be wireless interference? We use wireless mics and in ear packs, as well as being in a casino where there is tons of wireless gear being used.

    I hate to just say its something I sometimes have to live with, but that might be the case. My boss is a stickler for these things, and always tries to guilt everyone into buying this or that to fix even the slightest problems....this is a very slight problem and i've covered it up by putting a gate at the end of my chain, but thats a bandaid, not a fix.
  4. kb9wyz


    Sep 8, 2008
    I could be wireless interference, but I certainly wouldn't know unless I heard the noise. RF interference will vary in frequency depending if the source. You would likely be picking up a sideband of the fundamental frequency. The RF will directly induce a signal in your electronics. AM interference will produce an audio signal, FM will sound like irregular static.

    Either way, as SGD said, shielding will take care of this.

    Being an amateur radio operator came in handy today.:hyper:
  5. Check and be sure the bridge pickup cavity is shielded and grounded. Fender tends to neglect that part.
  6. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    It sounds like RF interference. You can try putting a 5 or 10 pF capacitor across the output of your bass, wired like you would the tone cap from hot to ground. That will remove RF interference.
  7. I put in a call to Monster, since they claim their product we own is intended to fix this problem. They claim I need to ground my power supply for the pedal board and say I'm picking up electro-magnetic garbage from the building I'm playing and amplifying it through my pickups. According to them grounding will fix it.

    This might end up being another customer service call I log as bad info, but I'll give it a try. I also like the 10pF capacitor on the output idea. Thanks!
  8. bassbenj


    Aug 11, 2009
    Sounds like pickup from a high frequency power supply to me. Pedals and such sometimes use them. I have a reverb pedal (not used with bass) that does that. I've filtered it all over the place and only reduced the problem not eliminated it. Since it's casino-dependent it may be as you say some casino wireless rig (the power supply in some unit) or other gear.

    To test it. First see if the noise level (high note) changes when you touch ground (strings, jack, etc.) If it does the pickup is electrostatic and you'll need more copper shielding to eliminate it. If not But the level changes as you move the orientation of the bass around then it's magnetic noise. not only rotate yourself around but also try to change the bass orientation as well (including angles where it can't even be played to see if you can "null" the noise. If you can find a "null" that means the noise is magnetic. Since the pickups are noiseless such pickup should be MUCH reduced from single coils, but they aren't perfect and some may still get through. See if moving your bass close to any particular piece of gear makes it louder. If it does that is probably the culprit. On the other hand try moving the cord end around not plugged into the bass. Turning the volume down may short the cable giving you the impression that the noise is coming from the pickups when it's not.

    If all else fails try turning off and removing any gear that may have a high frequency power supply one by one to see which one makes it go away.
  9. Stealth


    Feb 5, 2008
    Zagreb, Croatia
    Very cool trick, I didn't know about this one. :)
  10. R&B

    R&B Both kinds of music: Rhythm AND Blues! Supporting Member

    Reviving this helpful thread. Sizzling is my issue, and only on the brand new MIM FSR J bass, stock. Still in the return period, but got a killer Black Friday deal. Plus it is a beautiful, resonant tone monster. So I'd rather fix it.

    Will do some experimenting with amps, cables, locations etc. but it sounds like I need to shield the control cavity. Best place to get the foil? Don't wanna paint as it is irreversible.

    Other insights? Loose jack from those darn Monster cables they use at GC? Bad solder joint? Pup issue? (sizzle, sizzle).

    Thanks guys.