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Active and Passive inputs on the Bass amp

Discussion in 'Amps and Cabs [BG]' started by madjazzbass, May 19, 2018.

  1. madjazzbass


    Jan 5, 2014
    Some amps have separate inputs for Active and Passive Basses, and some (like mine) have a Active/Passive switch; thing is, I never flip that switch when I'm switching between active and passive Basses, it just always stays wherever it is. Question: Is this, or Will this do any harm to the Bass head and or cabinets if I continue to use it this way? Does anyone else do this? Or Do most people switch the input to/from Active to Passive when they switch the Bass that they're playing from Active to Passive? ... or the other way around.
  2. Acoustic356


    Jul 3, 2014
    Think of it as a pad. Most active basses are louder than passive basses, unless you have a pre-amp that will let you trim down the active boost.

    As a result, the Active/Passive inputs, or switch generally pads or decreases the input thereby reducing the signal applied to the amp.

    Depending on the amp, it could be 6db, 12db or somewhere in between.

    Yoiu won't harm your amp by using either with active or passive basses.
    madjazzbass likes this.
  3. The hottest bass I ever had was a passive. Go figure. Still didn't need the passive switched over to active.

    You won't hurt anything.
  4. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    the Cali Intergalctic Mind Space
    Song Surgeon slow downer software- full 4 hour demo
    If you keep the volume turned down s bit on your active bass, the volumes should be equalized between the basses.
  5. Garret Graves

    Garret Graves website- ggravesmusic.com Gold Supporting Member

    May 20, 2010
    Arcadia, Ca
    Also, most people call their bass ‘active’ when it only has an active pre-amp, but passive pups. Most basses with batteries have passive pups with active pre’s. If you aren’t boosting or cutting anything on your active preamp, you’re at a passive level anyway. You notice with boosting either bass, mids or treble on active pre that the signal gets hotter.

    My understanding was that active pick ups are very clean and clear toned, but super quiet- that is why they need a battery or power source, to get them up to a useable instrument level. I’ve always wondered why then an amp has the option to pad against a boosted signal, when the boost is meant to get TO instrument level?
    Last edited: May 20, 2018
    biguglyman likes this.
  6. Active means your bass has some type of electronics that requires additional power to operate such as a battery.
    Active electronics include components capable of amplification such as transistor devices. It does not necessarily need to increase the signal from the bass but if it has active components in the signal chain and needs a battery to run those components, it is an active bass.

    It does not have to provide bass or treble EQ boost to be active. It can have something as simple as a single FET stage to take the high impedances of a passive bass and lower the impedance to minimize the affects of long instrument cables.

    There are pickups that are called active, and don't require any additional amplification inside the bass. But those simply have the electronics built into the pickup enclosure. Otherwise you have a small, seperate preamp module/board, usually in the control cavity, that can work with stock passive pickups. In either case, this is an active instrument.

    The clean and clear tone you speak of comes from amplifying or lowering the impedance of the signal closer to the pickup elements, rather than running a very weak signal down an instrument cable where it is subject to picking up hum and noise and then start the amplification process. The hum and noise riding on the cable gets amplified along with the instrument signal. The hotter the signal coming out of the instrument Jack, (or the lower the impedance), the lower the hum and noise will be in relation to you signal.

    Passive components are resistors (pots), capacitors (tone cap) and inductors (pickup wiring).
    This is what you have in a passive bass.
    Active components are things like any of the various forms of transistors, Integrated Circuits, and tubes. Though you rarely find tubes built into a bass. Integrated circuits are just a way to package a number of transistor devices into a small space for specialized uses.
    Last edited: May 20, 2018
    ak56 and Kro like this.
  7. el murdoque

    el murdoque

    Mar 10, 2013
    I usually treat the active input / pad as a last resort when the gain pot won't work as I'd like it to.
    Old Garage-Bander likes this.
  8. madjazzbass


    Jan 5, 2014
    OP: I've come to realize that both Passive and Active Basses both sound better when I just leave the switch set to Passive; when I switch it to the Active, things sound sorta dampened or somewhat muffled and doesn't have the clarity like it has in passive mode. I'll just make minor adjustments as needed with the amp and whatever Bass I'm using at the time. :thumbsup:
  9. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    I'm going to muddy the waters and share that, on a couple of the amps I've owned through the years (Quilter BB800 and my old SWR back in the day come to mind) I counter-intuitively prefer the sound of a passive bass into the active input. Seems to give more headroom or something.

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