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Pots jazz bass. Bridge full open cuts neck pu

Discussion in 'Pickups & Electronics [BG]' started by Bas bassist, Jul 31, 2020 at 11:34 AM.


  1. Bas bassist

    Bas bassist

    Jul 24, 2020
    I need some help on my squier vm 70 jb.

    I am wondering if you know what could cause the pots when fully open cuts the sound of the other pu.

    So neck 100% i turn up bridge 100% and it cuts theneck pu.

    Does anyone know why (got 2 x b250k cts (vol) and 1x a250k cts (tone)
     
  2. Haha, that's called phasing bro. That's the sound of two pickups together. It doesnt cut the neck pickup, it scoops the mids. Every instrument with two pickups will do this. How much so, in what way, that all depends on the pickups and how they work together.
     
    packhowitzer, Ampslut and Bas bassist like this.
  3. Oh, but there's nothing you can do about that. That's just what happens when two pickups are working at the same time.
     
    Bas bassist likes this.
  4. Bas bassist

    Bas bassist

    Jul 24, 2020
    Yeah sorry im a newby...

    What i find strange is that they blend perfectly up to 80% turn of the pots... But when i turn one all the way up... The sound turns to awfull.

    So every jazzbass has the same?
     
  5. Yup. Even on the"blend" you really only get the tone from whichever ones hotter. If it's the bridge, you do get a slight increase in bottom end though.
     
  6. Bas bassist

    Bas bassist

    Jul 24, 2020

    Wow and all this time i thought that something was wrong .

    Thank you so much!!
     
    JeezyMcNuggles likes this.
  7. That’s not unusual. On a Jazz or a PJ I usually have one pickup all the way up then turn the other up then back it off until things sound “right”.
     
    johnnynitro and Bas bassist like this.
  8. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Try reversing the leads on one of the pickups. They may be out of phase. I’ve had a number of basses with that going on and swapping + and - on one pickup fixed it.
     
  9. Bas bassist

    Bas bassist

    Jul 24, 2020
    So if i understand it correctly i could try to swap the white and black wires from the pu to the pots?
     
    Killing Floor likes this.
  10. Slater

    Slater Leave that thing alone. Supporting Member

    Apr 17, 2000
    The Great Lakes State
    Yes. Just with one pickup.
     
    Bas bassist likes this.
  11. Funk With Me

    Funk With Me

    Tuesday
    This.

    I won a nice set of hand wound A5 pickups and had them installed in my jazz bass. With the new pickups I had the problem described in the OP. The cure was switching the two wires.
     
    Bas bassist likes this.
  12. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    Yeah, I just did that switch some Suhr/Fender pickups on one of my basses and it’s awesome now.
     
    Bas bassist and scuzzy like this.
  13. I had to reverse the leads on my P pickup to blend with my mm pickup. I also had to re wire the shield to make sure it was on the proper negative( cold, ground, shield... heard it called all sorts) with the pickup otherwise it was a serious humm/buzz.
     
    Bas bassist likes this.
  14. InhumanResource

    InhumanResource

    Dec 28, 2012
    More bottom from the bridge pickup?
     
    packhowitzer likes this.
  15. With the neck blended in.
     
  16. It should scoop the mids and sound good, sort of like a scooped stingray sound. If it sounds bad, then something is wrong.

    It IS totally normal for this dramatic tone change to happen with one pickup all the way up and the other all the way up, or just nearly all the way up. It's like a tiny unevenness in the levels in their volume controls suddenly emphasizes one pickup more than the other in a good way, but if you want them to sum evenly you need to use active pickups (IE: EMG active models) or an active preamp that actually has two buffered inputs before it's own internal pan or double volume controls... like how a mixer works.... which, by the way, is VERY rare. Nearly all bass guitar preamps use a passive pan control (or double volumes) on the pickups and then the pickups go into the single buffered input on the preamp.

    The possibility (which a few folks above mentioned) of a pickup being in reverse phase are worth a shot - it's an easy thing to try if you can use a soldering iron to reverse the wires on only one pickup. But if it does NOT fix it, you could actually have had them in phase before and made them out of phase now, in which case, once you do solve the problem (if possible, at least diagnose it), you probably should put it back the way it was, or at least don't forget you reversed one in case you wonder why it sounds weird in teh future.

    Another possible problem could be that the pickups are very mismatched. If one has a much higher resistance than the other, it COULD mean that you will hear the higher resistance pickup much more than the other pickup when both are turned on full.... for electrical reasons not worth detailing right now.

    So it's worth measuring resistance of each pickup to see what they are. Might need to disconnect a wire from each pickup to do this so they're no longer in the circuit, but I don't have a jazz schematic in front of me right now to tell you if you can get there with volume pot settings and not desoldering a wire.

    Also, one pickup could simply be higher output than the other (IE: louder, in which case you'd need to balance them to match well by adjusting pickup heights. I've had to raise a pickup to nearly touching strings and lower the other right into the body of the instrument when they were poorly matched, but doing so can make them blend well, at least.

    Those are all things you can try for free, if you're into experimenting with it.

    If they're really badly matched pickups it could be worth replacing one with a better match (and sell the one you don't like), or replace both with appropriate set (and sell both old ones).

    I mean, maybe it's fine how it is, and you just really hate a scooped sound. Scooped means mids are cut, while lows and highs still come through. I love scooped sound at times, like when slapping... but not always.
     
    Bas bassist and zie like this.
  17. Killing Floor

    Killing Floor Supporting Member

    Feb 7, 2020
    Austin, TX
    So now you need to let us know how it worked out. Should be a little better. Would be a pretty easy task. Good luck.
     
    Bas bassist and dkelley like this.
  18. Love your avatar, “Let’s face it, some people just don’t belong,hmm, hmm, hmm.”
     
    dkelley and rojo412 like this.
  19. Bas bassist

    Bas bassist

    Jul 24, 2020
    This sounds like you know what you are talking about.

    I bought the bass second hand so it is very possible that the pu's are not matched. I will unsolder the pu's and measure the resistance. If they are the same i will swap the wires.

    Its really worth the try before buying a new set of pu's

    Thank you so much in advance!!!
     
  20. I don't know if this answer was already given but here's my 1 cent. I agree with the phasing problem. I had this same problem when I was changing the pick-ups of my stratocaster. The only way ( from my experience ) that I solved it was to change 1 of the pickups to RWRP ( reverse wound reverse polarity ) and/or change the positive of one pup and place it to ground. As for the strat I upgraded the middle pick-up to a RWRP and the problem was solved. The peavey foundation bass that I have originally had one of the pick-ups RWRP thus did not have a problem. When I upgraded the electronics and pick-ups of the peavey , I had the same problem using the blend control. I resolved the problem using the mod from this link. I hope this helps.

    Ultimate No-load Ungrounded Blend Pot (Pics!)
     

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