Noobie active pickup question

Discussion in 'Amps [BG]' started by VBassRookie, Dec 24, 2012.


  1. VBassRookie

    VBassRookie

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    Dec 20, 2012
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    Wisconsin
    I'm new to the bass world so this may be a silly question, but this question doesn't exist in the non bass guitar world. I noticed that there is always (on most amps) a button or input for active pickups in regards to the input on amps. What is the point of active pickups if you are going to pad the input? It seems kind of oxymoron.
  2. the wako kid

    the wako kid

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    Denver,CO
    the idea is that you can change from a passive bass to an active bass without having the settings tweaked way high(for passive) and blowing up your amp.
  3. VBassRookie

    VBassRookie

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    Thanks, that makes sense. Curious though why you never see this on regular guitar amps.
  4. KJung

    KJung Supporting Member

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    This isn't totally correct, and adds to the confusion per the OP"s post.

    WAY back in the day, the early active circuits, for the most part, had a hire output than the older passive models (i.e., the Fender type basses at the time with no preamps). So, they uses 'active' and 'passive' as shorthand for 'high output and low output basses.

    This is in NO way the case these days. Many active preamps have internal volume controls, and many more are voiced so their output is about the same with the ciruit in (active) and bypassed (passive). Unfortunately, the 'acrive/passive' labels have carried through on some amps (although many now use a -15db pad indication).

    To the OP, there is rarely a need to use the 'active' input regardless of what type of instrument you have. The only time that the active input or pad switch is usefull is if you have massively aggressive technique, or a very hot bass (active or passive) that results in a distorted sound at the input stage of the amp, even when you turn the gain down.

    So, to the post above, there is no systematic difference in output these days between basses with and without preamps (due to the more modern preamp output levels described above, and also due to some REALLY hot pickups that put out a very strong signal). Also, you will do no harm to an amp by overdriving the input stage, and with a tube preamp, for many, that is exactly what they want to do, to get the growl and grind.
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  6. Got2SadowskyNYC

    Got2SadowskyNYC

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    KJung is correct.

    The Active input is a 10 - 15 db pad, depending on the amp. The side effect is that the highs are effected a bit. I've always used the passive input for this reason.
  7. KJung

    KJung Supporting Member

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    +1 The extra circuitry involved in the padding can actual impact the top end a bit. Another reason to not use the padded or active input.

    There are rare situations where the input impedance of the active input is lower than the passive input (passive instruments benefit from high input impedance). However, since active instruments don't care about input impedance, there is still no reason to plug an active instrument into an 'active' input.

    You CAN get into trouble (i.e., too hot of an input signal) with a passive input and an active instrument if you are cranking 10db of low end boost with the bass control or something, but that would be IMO user error and would sound like dog no matter what input you would use.
  8. wcriley

    wcriley

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    It also exists in the skinny-string guitar world.
    In many of the "classic" Fender (and many other) amps with two inputs pre channel, the jack labled "2" is padded down in respect to the "1" input jack.
  9. VBassRookie

    VBassRookie

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    i remember seeing high and low inputs on some of my old "skinny string" (I like that) tube amps. I didn't realize what they were.
  10. Tuned

    Tuned

    Joined:
    Dec 6, 2007
    Modern active pickup systems are really like having an active DI built into the bass, to isolate the pickups from the amp to prevent interactive impedance issues (something I actually like for fretted). There is no benefit to having a higher than normal output, so you'll find most active basses these days don't have an especially high output. I wouldn't consider an input pad to be a valuable feature unless you already have a high output bass.

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