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Active Input

Discussion in 'Amps and Cabs [BG]' started by lucyfur, Sep 15, 2010.

  1. I've got a Carvin AC40, which uses a piezo pickup and has a battery. I know I should use the active input on my amp, but what about if I'm first plugged into some effects pedals (Boss EQ and Chorus)? Does this still need to be plugged into the active input, or do the pedals act as a sort of pre-amp so I can use the normal input?
  2. Actually, the only reason to use the 'active' input is if the signal is so hot, the bass overdrives your preamp with the gain set low.

    The active/passive label is misleading, and is left over from the days when most active onboard pre's were hotter than passive basses. This is no longer true, as many preamps have internal trim pots, and many that don't are designed to have unity gain with the passive output of the bass.

    Sometimes, the passive input will have higher impedance, since low impedance inputs can suck treble out of the tone of a passive bass, but that's even rare.

    So, I would suggest using the 'passive' (i.e., un padded) input UNLESS you have clipping issues that you can't control with the gain control.

    Also, since your bass has an onboard preamp, the piezo pickup is buffered, and it acts like any other pickup (i.e., it doesn't need that super high impedance input to not sound clanky, etc.).

    You won't hurt anything either way, but I just don't like that extra padding down circuitry in my signal unless I really need it.

  3. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    Effects or no, the only time you really need to use the active input on your amp is if the signal going into the amp is too hot and you're getting clipping or overloading at the amp's input stage.

    The active input doesn't really have anything to do with whether the bass is active or passive--it just pads (cuts) the input gain, usually by somewhere between 12-20dB, so high-output basses (which may or may not be active) don't overload the input stage of the amp.

  4. Great minds think alike (and type at the same time too!):)
  5. Gearhead17

    Gearhead17 Supporting Member

    May 4, 2006
    Mount Prospect, IL
    Simple - use the Active Input when the signal is too strong for your pre-amp. If you plug into the Active input and you have to crank the gain knob quite high to get good volume, try the Passive input and see what happens. I plug my active basses into the Passive input all the time - the signal is not "distorting the pre-amp" by being too strong, so everything is ok!

  6. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    Some faster than others, apparently! ;)
  7. Gearhead17

    Gearhead17 Supporting Member

    May 4, 2006
    Mount Prospect, IL
    Man! I am not fast enough! Ha!
  8. Thanks for all the info. I learned something new today!
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