1. Welcome to TalkBass 2014! If you're new here, we just went through a major site upgrade. Please post all concerns and bugs to the Forum Usage Issues forum. We will be monitoring that forum. Thank you for all of your feedback.

    The TalkBass iphone/android app is NOT WORKING currently. We're working on it. Tapatalk IS working, so if you need to use an app, use Tapatalk. Try using your browser though - TalkBass is now 100% responsive to your phone/tablet screen size ;)

    Please read the TalkBass 2014 FAQ for lots of great info on the new software.

Passive/active. Question...

Discussion in 'Pickups & Electronics [BG]' started by JumboJack, Jan 2, 2014.

  1. JumboJack

    JumboJack

    Joined:
    Dec 31, 2007
    Likes Received:
    0
    Ok. So a bass with EMG type pickups is what we would normally call an active bass. An American Standard Fender J or P is passive.... I get that.

    But this is where I'm a little fuzzy. When you add a preamp like an Audere to a passive bass is it now an active bass?

    Also, an active bass (like my Carvin SB5000) is considered active/passive because of the push pull pot. But is it still active even when I put it in passive mode?

    The reason I as is I'm aware of pedals that are known not to play nice with active pup's (like the Woolly Mammoth) and volume pedal pots need to be the correct type and to a lesser extent where to flick the active/passive on an amp.

    Thanks!
  2. JustForSport

    JustForSport

    Joined:
    Nov 17, 2011
    Likes Received:
    0
    Simply put, pickups that are powered are active. Passive pickups are not powered.
    Adding a powered preamp makes a bass active, whether it has powered (active) pickups or passive pickups.
    I've even seen manufacturers advertise "active pickups" when the pickups are passive, and have no power going to them, but coupled with an 'active' preamp.
    There are quite a few active pickups avail, but most are passive.
    Research to verify if the pickups are in fact powered, and require power to have output, and will not produce an output without it.
  3. line6man

    line6man

    Joined:
    Jun 20, 2008
    Likes Received:
    2
    The convention of input labeling on amps arose from a huge misconception regarding bass outputs. You do not need to use the active input on an amp unless your bass is so loud that it distorts the input. Typically, the two inputs are identical, with the active input simply padded. It is not preferable to use the active input unless you need to.

    In any case, don't get caught up in the semantics of classifying active versus passive. What matters is the nature of the signal impedance. If there is a buffer in the circuit path, from an active pickup, or an onboard preamp, or perhaps something else, the output impedance is lowered. This is generally considered a good thing, for a variety of reasons. However, as you pointed out, it can cause issues when playing into equipment that is designed to see a higher impedance signal, or interact with the pickup coils' inductance. If this is the case, you will want to avoid the use of active components, by either sticking to a fully passive circuit, or bypassing active components. If you have active pickups, there is no way to have a high output impedance, unless you add something like an impedance matching transformer. If you have a preamp of some sort, with passive pickups, it may be bypassed, to allow for the high impedance signal of the passive pickups. When there is a mix of active pickups and a preamp, it is the same as just having active pickups; the impedance will always be low.

    Note, however, that though the impedance of passive pickups is generally always high, there are some pickups out there with a low impedance output. This is more-or-less the same as an active pickup, except that there is an inductive reactance from the coil(s). Sometimes low impedance passive pickups are wired up to impedance matching transformers, to increase output and output impedance. In this case, you can treat them like regular passive pickups.
  4. JustForSport

    JustForSport

    Joined:
    Nov 17, 2011
    Likes Received:
    0
    re: Carvin SB5000
    seems the factory pickups avail are all passive, so it's 'passive' when in passive mode, with the signal bypassing the preamp, even tho the preamp is still probably 'on'.
  5. JumboJack

    JumboJack

    Joined:
    Dec 31, 2007
    Likes Received:
    0
    Wow. Thanks for the great info...

Share This Page