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hum inductor circuit

Discussion in 'Pickups & Electronics [BG]' started by gimmeagig, Nov 24, 2012.

  1. Hi guys,
    I just fount this youtube video_One of my favorite bass players explaining this new noise reducing circuit that Xotic Basses came up with.
    I don't know anything more about this but it seems really cool.
  2. Not knowing anything about this, I would venture to guess that it is nothing more than a dummy coil. Probably buffered.
  3. Would that change the tone of the pickup?
  4. Yes and no. The goal is not to, but if the coil is not buffered, you alter the nature of both the real and complex parts of the impedance. My limited experience with a dummy coil was that it did not change the tone, but did drop the output, because of the resistive loading against the audible coil. If you buffer, you must account for changes in the circuit, such as the lack of parasitic capacitance from instrument cable forming a low pass filter with the pickups. For a proper buffered setup, each pickup would be individually buffered, rather than summed to a single-ended output for one buffer. This will change the tonality when both pickups are used, since they will no longer load against each other when blended, but rather, see a constant and purely resistive impedance from the buffer. Alembic does a buffered system, but I believe that EBMM's dummy coil system is passive.
  5. That sounds pretty complex. I was asking because I have a 74 jazz bass that is currently loaded with SCN pickups because I don't like the noise that the singles make when soloed. Together that's of course not an issue.
    If that new system works well in all positions ( individual pickups only and both on together) it might be a good idea to swap them out for the original pickups that I still have from this bass.
  6. bassbenj


    Aug 11, 2009
    Bad idea. Your SCN pickups ALREADY HAVE dummy coils in them! That's why they are noise free! Plus they sound absolutely amazing. I say that because my MIM Fender had "noiseless" pickups and the tone was awful. Those are typical two coils one for high strings and one for low strings pickups. They did NOT have single coil tone! Sorry.

    SCN pickups on the other hand are "stacked coil". that is a single coil pickup on top with a dummy coil underneath. Typically because the dummy is in series it changes the tone, but as far as I'm concerned with SCNs that changed tone is not bad.

    I've done some experimenting with dummy coils and I can say that putting a dummy in series (to cancel hum) definitely changes the impedance, inductance and capacitance of the pickup and that can really change the tone.

    Active dummy mixing (like Alembic) eliminates all that nonsense, BUT now you've lost the purity of a passive jazz bass. IF you don't care if it's active, that fine, but to me I'd like a passive hum-free system and so far my SCN pickups seem to get closest to that.

    I will add that I've heard clips of Nordstrand noisefree pickups that sounded very good but they are not cheap!