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Revers P Split Coil Pups --- replacement

Discussion in 'Pickups & Electronics [BG]' started by 83_Silberpfeil, Dec 28, 2013.

  1. 83_Silberpfeil

    83_Silberpfeil

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    Hello ---

    Looking for some guidance from the technical folks on this board.

    I am looking to replace some EMGs that were installed into my Yamaha BB1200S. I want to replace with stock Yamahas --- hoping to find a used bass that has them.

    My question is regarding the "reverse" P for the BB1200S. As you know, the half of the pup that is towards the bridge is positioned higher (towards the E string) and the half of the pup towards the neck is positioned lower (towards the G string)

    If I find say a BB450 or a BB300 that has the split P, but not reversed (e.g. opposite of what I described above), would it work on the BB1200S if I just switched the positions of the pups? Or are the coils wound in such a way that you can't switch.

    Much thanks for your consideration.

    Jonathan
  2. line6man

    line6man

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    For most split coils, each half is exactly the same. It doesn't matter which half goes where.
  3. 83_Silberpfeil

    83_Silberpfeil

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    Thanks for chiming in L6M. This simplifies my search.

    JC
  4. JustForSport

    JustForSport

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    Just check the outer dimensions of each half to be sure they'll fit...
    Also, the EMG's may be active, not passive, so check that they are the same, or you'll have to change pot values, besides.
  5. 83_Silberpfeil

    83_Silberpfeil

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    Here's an update. I paid a visit to my go-to luthier. He's very old school who's been in the business many decades --- more than I've been alive.

    He opened up the back compartment and confirmed that all the pots and the active preamp are indeed Yamaha originals.

    We saw that the lines connecting to the active EQ's were disconnected/cut. The previous owner who put in the EMGs (which were themselves ACTIVE) had to disconnect the 'ACTIVE' portion of the BB1200S in order to make the EMGs work. According to the luthier, EMGs were the 'in thing' maybe 10-15 year ago.

    So, I'll be looking for original Yamaha pups soon and swap out the EMGs --- my luthier will make sure everything is connected back properly, fine and dandy.
  6. 83_Silberpfeil

    83_Silberpfeil

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    JFS --- thanks for chiming in. Appreciate your comments!

    Can you clarify your comment about the EMGs being active/passive?

    My understanding is that the BB1200S being "ACTIVE" is "ACTIVATED" by the built in 'preamp circuit board' --- and that the original BB1200S pups are just "passive". That's why the PO, when installing the ACTIVE EMGs had to disengage the preamp.

    So, to get everything back in original spec, I should be looking for the passive pups and reconnect/engage the preamp circuit board --- do I have this correct?

    Thanks!
    JC


  7. JoeWPgh

    JoeWPgh

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    For the money, why not drop in Fralin, Norstrand, Lollar, Novak, or any of the very fine aftermarket pups? You could probably get one wound to your specs by a custom winder, and not have to buy an entire bass.
  8. line6man

    line6man

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    If pickups are active, they are pretty much guaranteed to work with preamps that were designed for passive pickups, because their output impedance is lower than passives. The exception, of course, is preamps that are designed to interact with the impedance of a coil. These kinds of preamps are uncommon, and usually still work with buffered signals. You just don't get the same functionality as with passives. It is very rarely necessary to remove/bypass a preamp in order to use active pickups. Bypassing the preamp was probably just a choice that the original owner made.
  9. JoeWPgh

    JoeWPgh

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    My understanding is the opposite. Most on board preamps expect to see the load of a passive pup. The very old EMG actives were from the time before onboard pre's. I think the OP is on the right path in pairing passive pups with his pre. But like I said above, he might be further ahead to have something wound to his specs than tracking down factory pups.

  10. line6man

    line6man

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    Do some research on input and output impedances. The output impedance of passive pickups is higher than that of actives, because active pickups are buffered. This means that the input impedance of the preamp designed for passive pickups is always appropriate for a signal of lower impedance than that of a passive pickup.

    The only downside to excessively high input impedances is that they can cause thermal noise. This is not significant in this application. The standard input impedance for preamps designed for magnetic pickups is 1M Ohms.
  11. JustForSport

    JustForSport

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    I've installed preamps (Aguilar, EMG, other OEM [Ibanez, etc] with older (active) EMG pickups and so far haven't had any problems with compatibility. Sometimes the active (as opposed to 'hz' models) had been in the bass w/o a preamp, only vol/vol/ tone.
    Also, haven't had any compatibility issues with active 'split P' pickups that were in earlier Ibanez and Hohner Cort-made basses.
    Active EMG's need a battery, even when used w/o a preamp, of course. Connecting an EMG or OEM preamp should be no problem, even if the preamp was prev used with passive pickups.
    It's just that the vol/bal/tone pot values should be 20k- 50k for active pickups, and 250k- 500k for passive pickups.
    Preamp pots are usually 25k or 50k.
    I'm not as familiar with impedances, etc, but what 'line6man' (knows his stuff) posted is right in line with what I've experienced.
  12. 83_Silberpfeil

    83_Silberpfeil

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    JWP --- thanks for the suggestion. I will explore this option and see what I find. If you know off the top of your head any particular pup model numbers that would work, please suggest.

    Thanks!

  13. 83_Silberpfeil

    83_Silberpfeil

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    Each of the EQ pots are 100K ohms. That's pretty much what I know. I do have the circuit diagram and wiring diagram, but not sure how to read the "input vs output" impedences.

  14. Grissle

    Grissle Supporting Member

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    FWIW I think what some are trying to say is that those EMGs should/will work with your preamp. Whoever bypassed it originally may either not have known what they were doing, maybe, or perhaps didn't like the stock preamp? I'd re-couple your pickups to your pre first and see how you like it. Hey, can't hurt.
  15. JustForSport

    JustForSport

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    ^^ Yes, as he said, and EQ should have original pots, no need to change.
    Only vol/bal/tone pots need to be matched to pickups.

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