1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Unwanted harmonics

Discussion in 'Hardware, Setup & Repair [BG]' started by pennradio, Oct 17, 2006.


  1. pennradio

    pennradio

    Oct 17, 2006
    Belleville, IL
    Hey there, I'm new to the forum but I've been reading it for years. There's so much wonderful information on this forum, I've never had to ask a question. The answer is usually right there for me, but no luck on this one.

    Ok, I've got a late 90's Mexican Jazz Bass with a Fender Original '62 @ the neck and a Seymour Duncan Basslines Quarter Pound @ the bridge. The bridge itself was swapped out for a Badass II and GHS Boomer strings. Now, whenever I play a D on the first string the fundamental holds out for about 2 seconds, but a harmonic 2 octaves up starts to ring out and kills the fundamental. It also happens on the C# (same string), but not quite as pronounced as the D. This works with any amp and I believe I can hear it acoustically, but I'm not sure. The string slot in the bridge isn't too tight or too loose, seems just right.

    This is no problem when playing short or staccato notes, but any time I want a little sustain out of this note that high harmonic just doesn't seem to cut it.

    Has anybody had this problem before? What did you do? Could it be a faulty string? Thanks in advance for your answer.

    -James
     
  2. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    Check and see if lowering the pick ups helps.
     
  3. Baryonyx

    Baryonyx Inactive

    Jul 11, 2005
    Marathon Man
    Yes, you could be getting some magnetic interferance from high pickups, or it could be a dreaded "dead spot".
     
  4. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Probably not the string, but trying a new set of something different
    can't hurt.

    IMHO, it is a typical dead stop, that most fender basses (and many
    others) have. Don't worry. It's normal. A possible fix is to use a
    Fatfinger. It is clamp on weight that moves the dead spot to where you
    probably won't notice it (I use one). Yes. It does affect everyone's
    technique, positions, note choices and articulation. :D
     
  5. WillBuckingham

    WillBuckingham

    Mar 30, 2005
    I think you'll probably find you just have to live with it. Even my Pedulla has a couple spots that don't decay quite right . . .
     
  6. pennradio

    pennradio

    Oct 17, 2006
    Belleville, IL
    I tried lowering my pickups, no luck. They were already at a decent hight.

    I guess it's a dead spot. I chose this Mexi because it had the straightest grain on the neck in the whole bunch. I guess even much higher end instruments have this problem.

    As far as the Fatfinger goes, I made one a few years ago (I'm DIY everything). I'll see if I can find it. Great suggestion.

    Still, if anybody has any other ideas, let me know.
     
  7. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    Guys, I'm sorry but these symptoms don't at all describe a dead spot. You don't hear any harmonics or overtones with a conventional dead spot.

    Pennradio, it's easy and quick to tell for sure if you have a dead spot. Simply put the end of the headstock against a wall while playing the offending notes. If its a dead spot, the note will clear up while the neck is held against the wall.

    If you are certain that the pup heigth isn't the prob, my next guess would be the string. Has the bass always had the problem or has it just shown up?

    good luck.
     
  8. emils

    emils

    Jul 28, 2005
    Croatia
    Sounds to me like a bad string or one of the saddle hight screws is not tightened correctly on that string.
     
  9. pennradio

    pennradio

    Oct 17, 2006
    Belleville, IL
    I have lowered the pickups (just barely over the pickguard), no change, just less gain. I noticed the problem today while practicing a new song. It may have been occurring much longer, I just haven't noticed.

    I also tried my homemade Fatfinger, no luck. I designed it for guitar and copied the weight of the real one. I seem to remember a separate bass version. I'll attach some more weight and see what happens. I'll try the wall trick too.

    -James
     
  10. Your problem reminds me of a similar one that I have on an ESP F-204 bass. I've got a deadspot on a B note (1st string, 4th fret). This deadspot is also on the same note at the 2nd string, 9th fret.
    When I'm playing a scale at the 1st string B note position, when I play that note, it causes my 3rd-string open A note to vibrate and mess with the B note. Drives me crazy, because in that position it's very hard to mute out the open A while trying to play anything on the 1st string.
    Since deadspots are basically the neck wood vibrating at the same frequency, cancelling out the note, it makes sense that the neck vibration can also cause overtones and harmonics to ring out also.. So.. it could be a deadspot.

    Just a thought...
     
  11. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    I learned a long time ago to never say never. Anything is possible.

    For the purpose of diagnosing a problem, though, the odds of it being a dead spot puts dead spots way down on the curve of probability.

    It's best not to totally discount anything. If the harmonic clears up with the headstock touching the wall, all bets are off. Lol.
     
  12. EADG mx

    EADG mx

    Jul 4, 2005
    The harmonic is most likely sounding on the 7th fret G string, or 5th fret D string. Try muting either of those and see if that helps. It's a quick fix but it should work.


    Also, maybe change your EQ?
     
  13. pennradio

    pennradio

    Oct 17, 2006
    Belleville, IL
    UPDATE:

    After eliminating the "too high pickups" postulate I tried the wall trick. It increased the time the fundamental note rang out (tripled I'd say) but the high harmonic was still present after a while. I also slapped on a new set of strings different brand (Dean Markley Blue Steel, similar guage) and got the same results. Even the wall trick turned out the same. I've been doing everything acoustically to eliminate EQ settings or other amp problems. And of course I'm muting the other three strings, but I guess I can't look over any options.

    The only thing that worked thus far was the wall trick. That led me to believe that it was in fact some odd dead spot. I added 75 grams to my already 115 gram DIY fatfinger. While it doesn't work as well as the wall, it has improved the length of the fundamental note to a point where I can work around the problem. With a little overdrive added the note can really sing, though not really a desired result when you only use an electric for surf and doo wop stuff.

    Maybe I just need to switch back to flatwounds.

    -James
     
  14. Stox

    Stox

    Mar 18, 2005
    London UK
    I get exactly the same as you, play a D on the G (7th fret) and the note decays quickly into a harmonic. This only happens when my plucking finger comes to rest on the adjacent 2nd D string though. If I strike the same note with a downstroke leaving the open D untouched the note sustains very well. Is this still a dead spot?
     
  15. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    "I've been doing everything acoustically to eliminate EQ settings or other amp problems. "

    You really should be troubleshooting it the same way you'll be playing it; through an amp. If you have something like a pick guard or cavity cover vibrating, it wont come through the amp. On the other hand if there is a string other than the problem string vibrating sympatheticly (sp?), it will come through the amp. That can be a good troubleshooting clue

    If the bass still has the problem while against the wall, it's definitely not a dead spot problem.

    What you are describing is a common result of magnetic coupling between the string and the pup magnet. Sometimes when a pup is changed, it's replaced by one with a stronger type of magnets. Stronger magnets agravate the prob. So you can understand why I'm hung up on pup heigth.

    Exactly how are you determining that that 's not the problem?

    Try using a bit of cloth under the A, D and G to completely mute them and see if the harmonic is still there.
     
  16. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    "I've been doing everything acoustically to eliminate EQ settings or other amp problems. "

    You really should be troubleshooting it the same way you'll be playing it; through an amp. If you have something like a pick guard or cavity cover vibrating, it wont come through the amp. On the other hand if there is a string other than the problem string vibrating sympatheticly (sp?), it will come through the amp. That can be a good troubleshooting clue

    If the bass still has the problem while against the wall, it's definitely not a dead spot problem.

    What you are describing is a common result of magnetic coupling between the string and the pup magnet. Sometimes when a pup is changed, it's replaced by one with a stronger type of magnets. Stronger magnets agravate the prob. So you can understand why I'm hung up on pup heigth.

    Exactly how are you determining that that 's not the problem?

    Try using a bit of cloth under the A, D and G to completely mute them and see if the harmonic is still there.
     
  17. pennradio

    pennradio

    Oct 17, 2006
    Belleville, IL
    To eliminate the pickup height I lowered both to the lowest point I felt safe with (I didn't want to strip the heads or dig into the wood any further). There was no discernible difference in decay time. Then I took a look at those huge pole pieces on my Seymour Duncan and though that lowering them might not be enough (though common sense would tell me that my Fender replacement, because it is further down the string, would be the more likely culprit for magnetic interference). Anyway, I taped strips of brass (.042in thick) I had laying around from a previous guitar shielding project over the pickups. This seemed to reduce the field by a large amount. I tested this by tapping a bare pole piece and tapping the brass (directly over a pole piece) with a small steel rod. There was a very noticeable difference in the force it took to pull the steel rod away. Still, no difference in the decay time of the fundamental note.

    If I'm wrong about this please let me know. I'm certainly no expert. Short of physically removing the pickups from the bass, I believe I effectively removed them from the equation. If there were any change in decay time with the shielded/lowered vs. control (normal playing height, no shield) I'd be much happier, having pinpointed the problem.

    BTW, thanks for everybody's help with this.

    -James
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.