Dimarzio Model J with LOW output, what did I do wrong?

Discussion in 'Pickups & Electronics [BG]' started by Basstovsky, Jan 7, 2014.


  1. Basstovsky

    Basstovsky The guy with the dumb username... Supporting Member

    Joined:
    Feb 29, 2008
    Location:
    Massachusetts
    So I love the Dimarzio Model J pickup, especially the old cream-colored ones, very warm and growly high-output pickup when wired in series.

    I just picked up another one, put it in a bass, and it sounded a bit... odd. When I soloed it, the G-D string coil sounded a bit lower in output (not significant, but noticeable) than the E-A string coil with all polepieces even, so I jacked up the ones on the G-D coil to try and balance it out. This was my first indication there was something amiss, as I usually don't need to muck with the adjustable polepieces.

    Then I brought up the volume on the neck pickup to hear its balance with the J, and realize that when I was playing the Dimarzio I actually had my amp up rather loud, for some reason the Seymour-Duncan neck pickup (rickenbacker humbucker replacement) is much MUCH louder than the Dimarzio, even when I barely have the volume knob turned up at all on the neck pickup.

    So clearly there is SOMETHING wrong with the Dimarzio, as in all my past experiences with the Dimarzio Model J, both vintage and new models, it should be a very loud aggressive pickup.

    So I figure, ok, maybe I have something weird with the wiring, and I check it and I've got black+white wires soldered together to put the coils in series, the green to ground and red to hot, so I decided to swap the red and green thinking maybe it is out of phase with the neck pickup and that's causing something weird with the signal? No dice, still sounds extremely weak and wimpy.

    Any idea what would cause the pickup to have greatly reduced output? In the past, I've had individual coils not work, totally dead pickups, out of phase pickups, but I've never had a pickup that should be high-output reduced to a very low output before, does anyone know what might be the problem?
  2. Shippy

    Shippy

    Joined:
    Dec 15, 2011
    Location:
    Fairport NY
    Green should be back of the pots... red to center lug of pots...

    Any reason to think the black/white is shorting to something? or did you use some elec tape or shrink tubing?
  3. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    From your description, it sounds like you wired it correctly, and trying the phase change was a good idea.

    The next thing I'd do is measure the DC resistance. According to Dimarzio, it's 6.82K, so anything out of that ballpark is a sign of trouble.

    The next experiment to try would be to wire the pickup directly to the output jack, with the controls and the other PU out of the circuit (remember to turn your amp down first!). If that sounds bad, it's a bad pickup. If not, the problem is in the wiring.

    One thing to consider is that this may not be the hot output pickup you're expecting. The Model J (dp123) actually has the lowest output of Dimarzio's J types, and the Rick neck pickup is very hot (not to mention that neck pickups in general will produce more output because the amplitude of the string vibration is greater there). Just something to keep in mind.

    Good luck.

    Reid
  4. walterw

    walterw Supportive Fender Gold Supporting Member

    Joined:
    Feb 20, 2009
    +1; also, measure DC resistance from that black/white pair to each outside wire, to see if one coil is different than the other. at 6.8kΩ series, you should be getting 3-something kΩ per coil.

    finally, look for something weird like the magnets not being right, say they've fallen off the bottom of the pickup or one side doesn't pull as hard as the other on a screwdriver or whatever.

    also, with a test magnet you should have one side pushing and the other side pulling.
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  6. Labi

    Labi

    Joined:
    Jun 14, 2006
    My Dimarzio J pickups have 5 wires and I haven't got a clue how to wire them. I searched the forum and the net but without any luck. Is there a wiring diagram for those pickups? The wires in each pickup are white, red, green, black and grey. I want to do a standard Jazz bass VVT wiring.
  7. mmbongo

    mmbongo I like turtles. Supporting Member

    Joined:
    Aug 5, 2009
    Location:
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    http://www.dimarzio.com/sites/default/files/diagrams/4Conductor.pdf

    Red = hot
    Black + White = solder together
    Green + Bare/Grey = ground
  8. Basstovsky

    Basstovsky The guy with the dumb username... Supporting Member

    Joined:
    Feb 29, 2008
    Location:
    Massachusetts
    I wired the pickup directly to its own jack (I had a spare) and it sounds exactly the same as it did before, a bit weak but the G-D coil is a little weaker than the E-A coil.

    I checked the resistance with my VERY junky multimeter, I get 8.1Kohms on the neck pickup and 6.67Kohms on the Dimarzio.

    I guess those 1.4 Kohms are a big difference in volume, as those are closer readings than I expected with the output difference I was getting, I definitely don't know everything that is for sure :D

    When I split apart the coils I get 3.27 from Green and White, and 3.4 from red and black, so this would mean something is wrong with my G-D string coil, that it is 0.13Kohms lower than it should be? Is there anything I can do to fix it, or just raise the heck out of the polepieces on that coil and hope for the best?

    I guess I've only used Dimarzio pickups with other Dimarzios, they always seemed to have rather high output to me, but I guess not high enough to keep up with the S-D eh? Maybe I'll try a different pickup to go with it, something closer to 6.8K.
  9. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    I don't know enough about Dimarzios in general to say with certainty if that small difference between the coils is meaningful, but I doubt that it is. You could try contacting the company. http://dimarzio.com/contact-us

    As for the 1.4K difference from the neck pickup, that's a completely different kind of pickup and direct comparison of the resistances doesn't necessarily predict the relative output levels. People often assume that higher resistance always means proportionately higher output, but that's not always true.

    Is this a new pickup? you might try to exchange it.

    I'm out of ideas.

    Reid
  10. Basstovsky

    Basstovsky The guy with the dumb username... Supporting Member

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    Location:
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    Thanks for the help, this was one of the vintage ones so it was a gamble seeing as how its something like 30+ years old. I'll have to pop on ebay or something and look for another
  11. midichlorine

    midichlorine Supporting Member

    Joined:
    Jun 15, 2005
    take a screwdriver and check the magnetic pull over each pole.

    if its a weaker pull on those 2 strings ( which it shouldn't be) then the pickup has possibly been "demagnetized".

    no matter how you've wired it it should have even pull.
  12. Basstovsky

    Basstovsky The guy with the dumb username... Supporting Member

    Joined:
    Feb 29, 2008
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    This is exactly what happens, the polepieces on the G-D coil barely pull on the screwdriver, while the A-E coil pulls it somewhat strongly.

    Is there a way to re-magnetize it? It's shocking the difference in strength between the magnets, very significant.

    edit: oddly, the magnets on the bottom of the pickup feel just as strong on both coils, but even on the underside, the G-D coil polepieces have a very weak pull compared to the E-A polepieces
  13. Basstovsky

    Basstovsky The guy with the dumb username... Supporting Member

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    Going to try switching around some of the polepieces to see if it helps at all.
  14. pfox14

    pfox14

    Joined:
    Dec 22, 2013
    I know you can get a pup re-magnetized and it sounds like that's a good place to go next.
  15. RobbieK

    RobbieK

    Joined:
    Jun 14, 2003
    Hmm, I have one of these in an old 80's bass. A great sounding pickup. (I'm not a fan of the P pickup of the same era though).

    This is a good idea. If it's an old secondhand one, someone could have replaced the pole pieces at some stage. I'd take one out of each coil and compare them. If they look the same, and have the same dimensions, I'd do some basic magnetic tests. eg, if one coil has grub screws that are from a different alloy, their ferromagnetic proterties will be different - IOW, differing magnetic attraction.

    If they seem pretty much the same, then take all 8 out, don't get them mixed up of course, and swap the 4 from the D/G into the E/A and vice versa. Also mark the G and E ends of the bobbin so you don't install it back the other way and defeat your tests. If you still have the same problem, then I'd guess the magnets are dodgey...
  16. walterw

    walterw Supportive Fender Gold Supporting Member

    Joined:
    Feb 20, 2009
    aha!

    what are the odds that one of the two bar magnets on each side of the coil bottom fell off and was re-attached wrong, facing the wrong way? that would totally fit your symptoms here.

    each pair of the bars should have the same magnetic poles facing inward towards the screws so as to impart the same magnet force into them.

    (don't bother removing the polepiece screws, they're just steel and all the same.)
  17. Basstovsky

    Basstovsky The guy with the dumb username... Supporting Member

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    Yeah I tried re-arranging them (keeping track where their original positions were) but it did not help sadly, so I put them back.

    What is a good way to tell the direction of the pole of each magnet?
  18. ReidK

    ReidK Jst sy n t lssy cmprsn. Supporting Member

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    The obvious answer is "a compass", but here's a link with various suggestions: http://www.kjmagnetics.com/blog.asp?p=which-pole-is-north

    If you use a compass, keep in mind that the earth's poles are labelled backwards. :)

    Reid
  19. RobbieK

    RobbieK

    Joined:
    Jun 14, 2003
    Of course! That's a very good idea. I forgot that these have only a little glue holding the mag in place. I have the P pickup in my hand right now. If one had come away, some one who's not too cluey with pickups is bound to put it back the wrong way, because the magnets will want to repell when they are placed correctly.

    I use a cheap orienteering compass I've had for years in these sort of situations. Sit the pickup upside-down on the bench. bring the compass to the side of the pickup to read the mags because they are pointing inwards towards the bottoms of the grub screws with this design. As you slide the compass across the pickup along its long side, the polarity will swing around as you go from the EA coil to the DG. You should get the same polarity readings on the other side.

    If one has been reglued in the wrong orientation, it may well be easier to remove the other three, (especially if they used half a tube of super glue or something), and re-orientate these to work properly. When you reglue the mags, lower the grubscrews down so the mags don't end up in a place that interferes with their positions, and use a little smear of grease on them so any squeezed out glue doesn't stop them from turning.
  20. walterw

    walterw Supportive Fender Gold Supporting Member

    Joined:
    Feb 20, 2009
    with another magnet.

    on each coil, the outsides of both bar magnets should be the same, with both sides of one coil attracting and both sides of the other repelling the same end of your test magnet.

    RobbieK has a good point, if one fell off and somebody didn't know what was going on, they could have let it fall back in place backwards because it would attract and hold itself in place instead of repel like it should.

    hell, try pulling on all 4 bars and see if one comes off too easily.
  21. kohntarkosz

    kohntarkosz

    Joined:
    Oct 29, 2013
    Location:
    Edinburgh - Scotland
    The 'magnet fell off' theory sounds like the best. I bought some Artec-branded Mudbucker pickups. Artec manufacture these with the magnets incorrectly fitted. The mags are strong enough, and the pickup metered a 'healthy' 30+ Kohms, but sounded weak and terrible until I fixed the magnet orientations.

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