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Pickup Gurus: Passive/Active BLEND?

Discussion in 'Pickups & Electronics [BG]' started by takeout, Aug 21, 2012.


  1. takeout

    takeout Supporting Member

    Dec 27, 2002
    Kansas City area
    File Under: Intellectual Exercise.

    So, plenty of basses come with active/passive switches. Would there/could there be any benefit to a Blend instead?

    I'm sure there are a host of issues with which I'm not familiar (output, impedance, etc.) Just wondering what the advantages or drawbacks would be.
     
  2. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    Right off the top of my head, there would be a problem caused with the input and output of the preamp being tied together that could/would cause oscillation. The pickups feed the input of the preamp and would also feed the output jack which is the output of the preamp. It could probably be done with a buffer circuit on the passive side but then it wouldn't be "passive".

    Someone may come along with a different answer or solution since I've never actually tried this.

    mech
     
  3. You're going to get a comb filter effect making any attempts to run the input and output of a gain stage together.

    I'm not sure why would you would want such a thing, either. There is no tonal difference inherent to active setups. It's all about what you do to the passive output from the pickups. Things like equalization need to be applied over an entire signal, not blended.
     
  4. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    yeah, active and passive don't "blend".
     
  5. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    I actually like seemingly nonsensical questions like this being posted on this board and others. Someone will come up with an idea that the tech types don't think of or have thought about and rejected but after some heads with different knowledge get together for discussion the idea is ironed out and found to be useful. This applies to more subjects than bass guitars.

    mech
     
  6. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    If you want to simulate blending from passive to active, make a preamp with an adjustable input impedance. If you lower the impedance you will get the passive tone.

    Another way is using a small value cap to load the signal before the preamp. So if you wire that up like a tone control (which it is), you can get a more passive tone.

    It's kind of the same idea as the Audere preamp's Z switches, but with a pot instead of a switch. You can try a small value cap like 470pF.
     
  7. mech

    mech Supporting Member

    Jun 20, 2008
    Meridian, MS, USA
    (Fixed the typo)

    There's a good idea that may give the OP what he want's.

    Probably the best solution would be to wire the bass with two outputs, one from the passive PUs and one from the output of the preamp. Use a two channel amp so the preamp input and output are isolated and blend and voice the amp channels as desired. It would need extra controls on the bass for passive volume, tone, etc, but may be worthwhile. Would probably be really good with an amp with one tube preamp channel for passive and the other solidstate for active.

    mech
     
  8. SGD Lutherie

    SGD Lutherie Banned Commercial User

    Aug 21, 2008
    Bloomfield, NJ
    Owner, SGD Music Products
    Thanks. Damn auto spell correction! I'm a sloppy typist and it thinks it knows what I wanted to write! lol
     
  9. Smilodon

    Smilodon Supporting Member

    Feb 18, 2012
    Norway

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