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Can you put active pickups on a passive bass?

Discussion in 'Pickups & Electronics [BG]' started by fleabass89, Apr 23, 2001.


  1. Maybe this is a dumb question... I've seen basses with active electronics and passive pickups. I don't really understand the difference.
     
  2. Saint

    Saint

    Mar 2, 2000
    DC - USA
    I may get this wrong, but let me take a stab:

    References to an "active bass" with "passive pickups" (e.g. Ken Smith, Wal) refer to a bass with passive pickups, but have an onboard pre-amp to shape and amplify the sound from the pickups. If you were to remove the pre-amp, the bass would (theoretically) still work, only its output would be lower and you would not have the same tonal shaping abilities.

    A fully active bass, I believe, would have pickups that do not operate without the addition of electrical current (in the form of a battery). Basses having real EMG and Alembic pickups fall into this category, I believe.

    If you are trying to convert a passive bass to active, the general question is cavity space: do you have enough room in your cavity to fit a pre-amp and battery (or batteries). The other question is whether or not you have enough slots drilled for the new controls you will be adding with your pre-amp.
     
  3. rickbass

    rickbass Supporting Member

    I think Saint pretty much captured it in a nutshell. But what you may be wondering is, "why?"

    Passive pickups are characterized as having very "pure" sound, and actives sound too "colored" for some tastes. So how do you get the purity of passives with the strong sound of actives? Wire the passives to an onboard, battery powered, preamp, (passive pickups wired to active circuitry). Some people find that even sounds too colored, so they remain with with totally passive instruments.
     
  4. Brooks

    Brooks

    Apr 4, 2000
    Middle East
    Actually, it is the other way around. Alembic invented active pups in order to get more natural sound. Passive pups tend to limit the frequency range, and to emphasize the midrange. By lowering the impedance, active pups work across a much broader frequency range. That is why they are also called 'HI-FI' (High Fidelity).
    "Purists" refers to those who like Fender's original sound achieved with passive pups. If you want to be a 'purist' in hi-fi terms (no frequency is being cut off, no frequency is being empasized), you should go with active pups.
    Also, true active systems do not have higher output, though they may. My Alembic (active pups with preamp) has output far lower than my G&L in passive mode, with preamp off. The purpose of the preamp in active systems is to bring the output of the low-impedance pups to a level that is workable, which is roughly the same as those of passive pups.
     
  5. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    The normal EMG pickup sets are exactly what you asked about, active pickups (each has a battery powered preamp inside the pickup housing) with passive tone control (single treble rolloff).

    The EMG Pbass and J bass setups are direct drop in replacements for Fender bassesl.

    There are five basic possibilities for a bass:

    1. passive pickups, passive EQ
    2. active pickups, passive EQ
    3. passive pickups, active EQ
    4. active pickups, active EQ
    5. passive pickups and EQ but an active gain stage (not very common)

    If either the pickup or EQ is active, you need a battery in the bass.
     
    dgrizzly likes this.
  6. Now I get it! I thought there's somthing wrong with my Alembic. It sounds way lower in volume to my G&L(both in active mode). But then I realise that there's a trim pot inside the cavityof my Alembic. I turn it up, and it's louder now.
     
  7. Max

    Max Supporting Member

    Feb 14, 2000
    Bakersfield, CA
     
  8. Brooks

    Brooks

    Apr 4, 2000
    Middle East
    I could be wrong here, but as far as I know, there is no such thing as 'passive EQ'. EQ is, by definition, active. You can have passive tone control though. The difference is that EQ can boost or boost & cut certain frequencies. Passive tone control can only cut.
     
  9. Regading passive or active, it's basically one's with battery, and one's without. Obviously when the electronics has no battery to power them up, then their capabilities in altering the tone is limited to minor "gain" boost or cut(i think more like cut). The overall gain is obviously lower than those active basses. In basses with passive electronics(assuming passive PU), you have to rely alot on the true acoustic timbre(sound) of the bass; because altering the sound is very2 limited due to minimum EQ control on Passive EQ.
     
  10. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    Brooks, passive EQ on a bass is rare, but the bass and treble controls on the G&L basses work in passive or active mode.

    A lot of older amps have passive EQ, the difference is that active EQ is boost only or boost/cut, passive EQ is cut only.
     
  11. Brooks

    Brooks

    Apr 4, 2000
    Middle East
    I have a G&L 2500, and tone controls are passive, even when the preamp is turned on. My point was that the term EQ is usually used for active tone controls.
     
  12. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    I misunderstood your point. Sorry.:oops:

    Calling passive tone controls 'EQ' may indeed be a misapplication in terms. I don't know.
     
  13. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    Some people use the terms "EQ" and "tone controls" interchangably...adding to the confusion;)

    Not sure what the rule is. Some say EQ must be cut and boost, others say a boost only control (Fender Marcus Miller Jazz) is still EQ...

    I have a G&L L2000E and the bass and treble controls do work in passive mode, which is rare. I don't know if they are boost or cut controls though.

    Max, when you put active pickups in a passive bass like a P you usually need to find room (or make room) for a battery.
     
  14. Brooks

    Brooks

    Apr 4, 2000
    Middle East
    EQ is short for EQualizer, and these are either boost/cut or (rarely) boost only. However, Tone control is always cut only. Tone controls on G&L are cut only, which also explains why they work in passive mode.