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alnico bass humbucker build

Discussion in 'The BASS Place' started by emosms, Mar 7, 2021.

  1. emosms

    emosms TDPRI Member

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    Hi, I am building a bass humbucker.
    Initially I wanted to make alnico stingray pickup, but I could not find large magnet poles.
    So I made it with two small poles (18 x 5 mm dia), like the JB pickups.
    Furthermore, due to the narow string spacing, they're a bit angled to fit.

    pup_front.jpg
    pup_back.jpg
    pup_side.jpg

    I definatelly will go for parallel wiring of the two coils. Aiming for ballanced tone, not too hot, that would (eventually) work well for slap playing.

    How many turns to make a coil? It will be scattered winding (lower capacitance, better top end).

    The coil is 13 mm high (taller bobbin, better top end). Maximum possible width of the windings (crossection) - 7 mm.

    The bridge pup on the bass is cheap chinese ceramic pickup. Total resistance of ~11k5 or 5k(smth) per coil.
    Still, it works ok, wired in parallel, getting ~2k6 total resistance.
    Isn't it too low ?

    pup_bass.jpg
     
    Last edited: Mar 7, 2021
  2. Reedt2000

    Reedt2000 TDPRI Member

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    Very cool! I'm not well versed in pickup building so I'm not sure about how many windings. I do know you are close enough with your poles to not worry about angling it for string spacing, it will work just fine. You could wind it for 4 conductors and do series parallel switching. When you get a result you're happy with you could build or buy a cover without poles exposed and it will look factory. You might wanna thumb through this thread:

    https://www.talkbass.com/threads/magnets-copper-wire-a-pickup-building-thread.1374810/#post-22021144

    Keep us posted on progress.
     
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  3. emosms

    emosms TDPRI Member

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    Reedt2000 likes this.
  4. jsiddall

    jsiddall TDPRI Member

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    In general scatter winding will reduce top end due to the physically larger coil size. The thread above from post #2 has a huge amount of information, including discussion of scatter versus tight wound coils, so definitely read through that.
     
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  5. emosms

    emosms TDPRI Member

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    Depends on how much scattered it is :D
    But it also reduces coil capacitance (as if you put a capacitor parallel to the coil)
     
  6. emosms

    emosms TDPRI Member

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    I cannot really control how much scattered it is with my DIY handdriven winder.
    It turned out pretty random..
    Also, it is not possible to make it tight wound.

    viber_image_2021-03-11_11-02-15-1.jpg

    viber_image_2021-03-11_11-02-15.jpg

    Made it ~9000 turns per bobbin, ~7k5

    Not tested yet :D
     
    Last edited: Mar 11, 2021
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  7. emosms

    emosms TDPRI Member

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    Puckups are more bright than the stock ones. I was aiming that.

    As observed with guitar pickups, the general case is that alnico pickups have more natural sound - they pick better the metallic sound of the strings. Also handling the dynamic peaks better - less distortion and treble harshness when u hit hard.
    Still picking the harmonics and treble better, when playing softer.
    Finally, they sound better if the treble EQ is boosted. The stock ones were getting plain harsh doing that.

    There were some troubles - the bobbins top and bottom plates bend outwards at the ends (bow like), due to the coil tension.
    So, winding should not be carried too fast. It is getting too tight and u create large asymetric areas leading it by hand.

    I broke one bobbin, trying to straighten it with carpentry clamps. I also damaged the winding, so I had to remove and rewind.
    I even aplied droplets of fast glue on the wire (at the short sides), every ~ 1500 turns rewinding the broken one.

    Holefuly finished with that. One of the bobbins is slightly bent.
    All potted in parrafine only (no bee wax).
    It melts at lower temperature, so I do not eventually damage the bobbins.

    IMG_20210320_164618.jpg
     
    Last edited: Mar 20, 2021
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  8. emosms

    emosms TDPRI Member

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    Finally I tested through the active EQ. But, I dont like how the blend pot works:
    blend_pot.png
    At the mid position, the blend sound is very prominent (and I like it most).
    But as soon as I turn left/right, there is a very little room for smooth transition between pickups.
    The tone abruptly changes towards one of the pups.

    I think of buffering the pickups:
    buff4.gif
    But I don't know how the circuit would handle short to ground (end positions of blend pot).

    Buffering would handle the pot load and bring back some trebble.
    Up til now, I was testing the pickups with no pot load - connected to amp directly.
    The blend pot load seems to be 250k || 250k ~125k
     
  9. emosms

    emosms TDPRI Member

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    What about this:

    buf_blend_v01.jpg
     
  10. jsiddall

    jsiddall TDPRI Member

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    I assume that you have an MN-taper pot? I doubt a buffer will help with this issue, which sounds like a taper preference, but it wouldn't hurt to try if you have one or can build one easily.
     
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