active and passive inputs of an amp

Discussion in 'Amps and Cabs [BG]' started by natas, Jul 22, 2013.

  1. natas


    Mar 14, 2013
    what happens when you put a passive bass to the active input ona an amp,and when you put an active bass to a passive input?

    also,if you use a passive bass with an external (pedal) preamp,should you use the active input of the amp? how bout multifx with preamp emulator?
  2. Amps have active inputs in case you have a seriously hot signal to go into it. In my experience only my RBI would have required the active, all my active basses go fine into passive input with the input gain down a bit.

    Generallly, anything in the way of foot pedal processors will probably be the same for you, but if it overdrives the input use the active, no harm.
  3. That is a 'mislabeling' of those inputs, left over from WAY back in the day when the early active on-board preamps typically had higher output than the older passive basses. That is not the case these days.

    Per the above post, 'active' input just means it has some extra circuitry that pads down the input so the first stage of your preamp doesn't clip with a VERY hot signal. You would rarely use this input unless you really had a massively hot output bass (active or passive).

    Start out with the 'passive input' with any bass/pedals'. Only if you have to turn the input gain down almost all the way and/or hear distortion even at very low gain settings would you then move to the active input.

    Regardless, you can do no harm with an combination. You won't hurt anything using any combination of bass, pedal, input.
  4. davidjackson


    Sep 10, 2011
    To add to that, Ashdown even recommend experimenting with running active basses into the passive input on their tube amps for more variety.

    I don't think you can do any harm as KJung says.
  5. Again, all that will happen moving from an active to a passive input is a hotter signal to the amp. Especially with a tube front end, that will result in a hotter input signal capable of pushing the tubes a bit more, which I think is what they are saying.

    Absolutely NOTHING bad can happen using either input with any bass. In my many decades of playing, the only instrument I've owned that I use the pad switch or the active input (depending on the amp... they do the same thing) is my Rob Allen Mouse, which has a super high output buffered piezo pickup.... really hot signal!

    Won't hurt using either one, but again, using the passive input (or keeping the pad switch off) will result in the most direct signal from your bass to your preamp, so this should always be the default input to use, unless there is a reason (overdriven preamp that you can't control with the gain control) to put that 'gain reduction circuitry' in your signal path.
  6. elonoic


    May 29, 2013
    Oporto, PT
    what if there's no gain knob? should I still use the passive input and listen for distortion?

    (Sorry OP for using your thread)
  7. What amp are you using that doesn't have a gain knob? Interesting.

    Yes, if for some reason there is not an 'adjustable input gain knob' on your amp, then the active/passive input would be useful, basically serving as an input gain with two settings versus the infinitely adjustable gain pot.
  8. Lo-E


    Dec 19, 2009
    Brooklyn, NY
    Yup. Start with the passive input and if it sounds clean (or distorted the amount that you're looking for), stay there. If it breaks up more than you like, move to the active input.