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Passive pups, active electronics

Discussion in 'Pickups & Electronics [BG]' started by geggy spoiger, Nov 6, 2004.


  1. Hi!
    I'm a little confused by the combination of passive pickups with active electronics. What is the purpose? I get passive...i get active, but what kind of sound is obtained when putting the two together. Is it a little bit of vintage (passive) with some modern zing(active)?? Also, would you plug one a bass with this package in a padded or unpadded input for optimum results?? Specifically, i'm speaking of the electronics package in the Warwick jazzman's.
    Thanks in advance!
     
  2. 5stringDNA

    5stringDNA

    Oct 10, 2002
    Englewood, CO
    I'm no electronics expert, but essentially the active pickups give you a "hotter" signal. Active pickups usually are not as transparent sounding as passive pickups- they put more "color" in the tone. Because tehy are active, they require batteries as well- I have never seen active pickups without a pre-amp, but I don't know if it is possible to have active pickups with no preamp. It seems like you could do it, but that would be somewhat self-defeating. Passive pickups on the other hand can be used with or without a preamp. The preamp boots the signal in most cases, ads tonal shaping. Many bassplayers prefer passive pickups with an active preamp so that the natural tone of the bass comes through the pickups, but it can either be shaped by the preamp, or left alone for a natural passive tone. My custom has an active bypass switch on it- it allows me to turn off the the preamp and just use teh passive pickups. It is not as loud or "hot" this way, but the tone sounds more natural and woody.
    I hope this explains a bit!
     
  3. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    Pickups can be active or passive
    Electronics can be active (bass/treble) or passive (tone control)

    You can have any combination of the above
    Combining passive pickups with active electronics has a couple of advantages
    a) You get on board eq
    b) Generally you can bypass the preamp to get the passive bass tone if that's what you want
    c) If the battery dies and you have bypass, you can still be heard - not the case with active pickups.

    As for amp input, I generally use the regular one and adjust - whether active or passive, you're trying to max your input gain without distorting.
     
  4. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    That's because some manufacturers, like EMG, choose to put some EQ curves into their pickups preamps. It's not an inherent feature of active pickups.
    Active pickups have a preamp built in to them. You can still have passive electronics i.e . only vol and tone controls.
     
  5. thanks to you both for clearing some things up!!
    That was fast posting!
    Thanky again. :)

    Michael.
     
  6. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    active pups have a built in preamp (sometimes in just the neck pup with the bridge actually being a passive pup). All you need is a battery. No battery, no (or barely audible) output.

    You get some tone shaping with an onboard preamp but in my experience nothing of much significance or nothing you can't get through adjustments in amp or eq. Mostly you get onboard control of boost/cut (with current preamps). Again, most or all of which can be had through most current amps. If you boost passive output equal to active output, you'll get similar results - excluding what the preamp does to the tone.

    I like active pups on occassion but I'll take a set of good passive pups ran passive 90% of the time. In my experience, onboard preamps strip all or nearly all of the rawness (what I'd also call color) from any passive pups that have it. To me they seem to actually filter the tone. The positive side of which is there's a significant reduction in any noise the pups may put out in terms of 60 cycle hum, extraneous interference, and finger/pick transfer.

    Also, most of the by-passes on active/passive basses are not a true by-passes (if you pull the battery and get nothing in passive mode, it's not a true by-pass) so you don't really get the straight sound of the passive pups. There's a marked difference with a true by-pass.

    The acoustics of the bass and general character of the pups will show through any preamps I've ran whether passive or active. It will just be different.
     
  7. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    The primary purpose of active electronics is to provide a low impedance signal source, so you can drive very long cables with minimal pickup of hum and noise. This is true whether the electronics are "inside the pickup" or on a separate circuit board.

    Most manufacturers add "active eq" into the active preamp circuit, which provides the additional benefit of being able to cut and boost particular frequency ranges. Ordinary passive tone controls can't boost, they can only cut.

    When passive pickups are connected directly to the instrument cable, the whole system (amp->cable->instrument and back again) becomes a gigantic antenna. Also, a side effect of this arrangement is that "ground" on your instrument is no longer the same as "ground" on your amp (because, instrument cables aren't "perfect conductors", they have resistance, capacitance, and inductance). Grounding problems are endemic to passive instruments, and the easiest (and probably the best) way to address them is to lift the ground from the pickup coil, and use a differential input active preamp that matches the pickup impedance. In 99.9% of the cases, this will result in a completely hum-free instrument that can drive long cables with impunity.
     
  8. geshel

    geshel

    Oct 2, 2001
    Seattle
    You'll need well-shielded pickups to fully realize this, of course - right? In other words, no exposed pole-pieces.
     
  9. A9X

    A9X

    Dec 27, 2003
    Sinny, Oztraya
    Not in my experience.
     
  10. geshel

    geshel

    Oct 2, 2001
    Seattle
    Also, it is impossible to remedy the mostly magnetically-coupled 60-cycle hum from nearby transformers and motors without either humbucking pickups or a dummy coil. Maybe that falls into the 0.1% -- though I'd think that if a balanced system were really sufficient when using single coil pickups, Ron Wickersham would have known that before stuffing a dummy coil into his Alembic basses.
     
  11. Zombie thread...

    Sorry for digging up the past fellas, I'm just curious about this discussion and the grounding differences between active and passive electronics...

    If say a jazz bass with passive humbucking pickups and passive electronics is perfectly shielded will the "ground" in the instrument not be the same "ground" that is in the amp?

    Also with this setup, will the passive instrument still be hum-free that can drive long cables with impunity? If not, how long can the cable be before it starts to pick up interference?
     
  12. I don't think you are understanding the purpose of buffering and preamps. Some preamps have a tonal signature, but that is not the only reason you would want them. Many are designed to have no effect on tone.

    I explained this once, here.
     
  13. tylerwylie

    tylerwylie

    Jan 5, 2008
    Roswell, GA
    You know most of the posts in this thread are 9 years old right? :p
     
  14. I didn't pay attention to the dates.:hyper:
     
  15. Hey Line6man, I was the one that revived this thread. I just read through the link you just posted and read about your post regarding the "lowered output impedence". From what I read, I assume with using passive electronics and a long cable run there will be a degree on "tone suck". How long does the cable run have to be before this is noticeable on a passive bass that is shielded properly?
     
  16. It depends on the cable, and the impedance of the pickups. And also, your ears. Some people don't notice it, others think it ruins their tone. Some people like it, as well.
     
  17. Thanks Line6man. I have a couple of other questions for you, if you don't mind.

    1) I have a Warwick Rockbass Streamer LX (Passive MEC PJ pickups and an MEC 2-band onboard EQ), and the single coil bridge pickup has some of the loudest 60 hz hum I've ever heard. I've heard that the 60 Hz hum of single coil pickups gets reduced with active electronics. Is this true? And if so, could there be an issue with my MEC preamp or bridge pickup?

    2) One of the replies above states that, "a side effect of this arrangement (passive electronics) is that "ground" on your instrument is no longer the same as "ground" on your amp (because, instrument cables aren't "perfect conductors", they have resistance, capacitance, and inductance). Grounding problems are endemic to passive instruments, and the easiest (and probably the best) way to address them is to lift the ground from the pickup coil, and use a differential input active preamp that matches the pickup impedance. In 99.9% of the cases, this will result in a completely hum-free instrument that can drive long cables with impunity."

    Is this true? I always thought if you properly shielded a passive bass, you would reduce all hum but the 60 hz of the single coil pickups (if that's what's being used), and the bass would be properly grounded, and the ground would be the same as the one in the amp, but the statement above makes me think otherwise.

    Thank you
     
  18. 1. This is nonsense. You might even make hum worse by boosting frequencies in the 60Hz area, or 120z, 240Hz, etc., where the harmonics of 60Hz are. Additionally, an active circuit can add noise.

    2. I have yet to hear of anyone doing differential preamp inputs. That is something that is common to active pickup designs, but not preamps, buffers, or any other sort of active component on a bass that is not internal to the pickups.
     
  19. Great, thanks line6man for your expertise. I have a passive bass that I was contemplating adding active electronics into, so I searched a bunch of threads looking for a purpose for it other than tone shaping. Your answers have cleared up some things for me.

    Thanks again,

    Matt.