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Active bass = noiseless p'ups, passive = not?

Discussion in 'Pickups & Electronics [BG]' started by jenderfazz, Aug 14, 2004.

  1. Generally, I've seen that active basses tend to have noiseless pickups. I'm generally talking about J pickups here. Fender, for example, offers a variety of noiseless pickups on their active basses, from the "noiseless" to the "samarium cobalt noiseless" to the old single pole per string Suhr ones. However generally all of their passive basses have traditional single coils, with hum if one pickup is soloed. Similarly, most active Fenders do not have single coils, and few passive Fenders have noiseless pickups. Is there a reason for this?

    I'm wondering if this has something to do with impedance and seems to suit a particular impedance best. Or maybe it's just because active basses sound different from passive basses, from the get-go, and so they might as well add the noiseless pickups since it doesn't matter that dual coils don't sound like single coils anymore. Or maybe it has to do with active pickups and passive pickups and all that stuff. Anyone care to take a stab at it?
  2. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Several things to realize:

    a) there's no such thing as a "noiseless" pickup. That's marketing hype, pure and simple. Some pickups are quieter than others, but it usually has more to do with the arrangement of multiple coils, rather than impedance issues.

    b) active basses are usually quieter than passive basses, but the reasons are complex. We'd have to discuss electronics in some detail to get to the bottom of that issue.

    c) 99% of all the basses in the world are wired incorrectly in the first place, from the standpoint of minimizing hum. Most manufacturers ground one side of the pickup. That's a bozo no-no if you want a hum free instrument.

    d) it's entirely possible to have a very quiet bass with single coil pickups. I have one active bass at the moment, with single coil pups, that I can stick right up next to a fluorescent light fixture, and run it at full volume through a 2 kilowatt amp, and not hear "any" hum, not even a "tad" relative to the amp's ordinary output level with the input disconnected.

    As far as why Fender does the things they do, my answer would be: marketing. My belief is that Fender addresses their markets, and nothing more. They're in business to make money, not necessarily to make great basses. There's a single coil market 'cause there are people who love that sound. They make active basses 'cause there's a market for them. Les Paul would roll over in his grave if he looked inside an active Fender bass with "noiseless" pups. Search Google using the combination of "Les Paul differential" or "Les Paul balanced" and see what you find. I'll bet you'll come across the story. :)
  3. Correlli


    Apr 2, 2004
    New Zealand
    Active Pickups - Low impedance, wider frequency response, low noise, need preamp to boost signal, more versatile.

    Passive Pickups - High impedance, organic tone, uncluttered sound, lose high end when using a long cable.
  4. David Wilson

    David Wilson Administrator Staff Member Administrator Supporting Member

    Oct 14, 2002
    Lower Westchester, NY
    as nonsqtr said, there are many variables... An active bass with poor shielding or grounding can be just as noisy as a vintage single coil bass.

    I've tried some single coil pickups (Aeros) which with regular shielding are extremely quiet. I've had humbuckers which required extra shielding to avoid hum.
  5. Nino Valenti

    Nino Valenti Supporting Member Commercial User

    Feb 2, 2001
    Staten Island NYC
    Builder: Valenti Basses
    I don't understand. :confused: How would you wire a single coil differently to aviod hum when it is played solo or played at a different level then the other pickup?

    Are you refering to both pickups on at the same level or one pickup soloed?

    I'm not trying to be confrontational as it seems when I'm re-reading my comments. I'm just curious because I like to play my bass with the blend knob slightly favoring the bridge pickup & when I do this with a bass with single coil pickups (Active or Passive) it hums. :)

    I wouldn't say Marketing, I'd say Accounting. The less expensive basses get the less expensive (to produce) pickups & the more expensive basses get the more expensive (to produce) pickups.
  6. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    What I'm saying is: "Don't ground one end of the pickup". That's just asking for trouble, from an electronic standpoint. The only part of the pickup that should ever be grounded is the casing.

    You can easily solve this problem with an active bass, by using a "differential" (or "balanced") connection between the pickup and the preamp. With a passive bass it's a little harder to address, 'cause you'd need to run a balanced (XLR, or TRS) line between the instrument and the amp. Les Paul was a big advocate of this method, and he had several of his amps and instruments modified for this purpose. It never really took off in the industry, 'cause the technology is a lot more expensive. I haven't seen too many bass amps with balanced inputs. The optimal compromise, as far as I can tell, given that your amp will have a single ended input, is to run an active bass with a balanced connection between the pups and the preamp, and use a low impedance source to drive the single ended connection between the instrument and the amp.

    For some reason, even the active bass manufacturers haven't caught on to this, most of them still ground one end of the pickup. The preamp will "help" in this case, but as you say there will probably still be some hum. In the vast majority of cases, you can make your single coil pickup considerably quieter (and less responsive to external EMI) by connecting it into the preamp the right way. Drop me an e-mail if you'd like to see a schematic for a simple circuit that does this, you can build it for about ten bucks in parts and maybe a half hour with a soldering iron. I've used this circuit on half a dozen of my passive basses, installing an active differential preamp and lifting the pickup grounds, and the results are absolutely consistent. I get a quieter instrument, and I've never experienced a downside (other than having to change the battery every once in a while). :)

    Edit: by the way, those are some nice looking basses on your web site. :D As a creator of fine basses, you're probably in an ideal position to experiment with and understand this issue. If I were you, I'd think about offering it as an option. Try this: select a bass that you think hums too much. Install my circuit (let's communicate while you do that). Then listen to the results. My "acid test" for quiet basses is the fluorescent light fixture thing I mentioned. After the mod, you should be able to stick your pickup(s) right up next to the ballast, and the bass should be perfectly quiet. There will still be some issues around specific kinds of single coil pups (and also, "active pickups" will be slightly problematic, since some of them can not be easily connected to a differential preamp without additional electronic finagling), but by and large the result should be a hum free instrument.
  7. AlembicPlayer

    AlembicPlayer Im not wearing shorts

    Aug 15, 2004
    Pacific Northwet, USA

    this is a great discussion...but I must interject

    Mr.Les Paul is not dead..matter of fact he plays live every Monday night in Manhattan.
  8. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Well, you can ask him then... :D
  9. babaseen

    babaseen The New M'Taboo Supporting Member

    Apr 15, 2001
    Boston, MA
    Just a side note....my Trace Elliot AH250 (purchased back in the mid 80's) has a balanced XLR input (as well as the regular 1/4" guitar jack)...too bad I don't have a bass capable of taking advantage of this feature.