1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

wait wait wait..the bass itself has a preamp??

Discussion in 'Basses [BG]' started by progrmr, Sep 4, 2008.

  1. progrmr


    Sep 3, 2008
    Columbus, Ohio
    ** BEWARE - Noob question **

    I thought the bass plugged into the amp input, the signal goes to the preamp (in the amp), massages the signal, then sends it to the power amp.

    Is it just some basses also have an additional preamp on the guitar itself?? Where the heck does it fit? And why have 2??
  2. stflbn


    May 10, 2007

    An "active" bass usually has 2 or 3 band preamps on the bass. If you look at basses and see one with 5 knobs that's almost always a 3-band, 2 pickup bass. Bass, Mid and Treble controls.

    They add more tonal versatility coming directly off the bass. As far as I'm concerned their great for live use song to song to adjust tones specifically to match the needs of different songs. Some feel that an Active bass has more of a modern feel or even an 'active' sound as opposed to a passive bass. Personally I feel that the quality and types of preamps are more to blame for the sound then the idea that it's an active bass. I've got active preamps in each of my current basses and all are setup active/passive via switches, and I see NO sound change at all in any of them when I switch from passive mode to active mode. To me it's the best of both worlds and very versatile adn adaptive. You can accomplish a lot tonally without turning around and fiddling with an amp between songs.

    Regarding where do they fit.... the preamp it'self is the little black box. This one runs 18volt via two 9v batteries, but can also run just via a single 9volt battery.
  3. Bassamatic

    Bassamatic keepin' the beat since the 60's Supporting Member

    One of the big problems with electric guitars in general is that the output level of the pickups is REALLY small, and it is high impedance. This means that the signal is easy to get noisy, and that things like the capacitance of the cable and the input impedance of the amp can affect the sound. Also - you can only have tone controls to CUT the tone, no boost.

    A while back someone started making ACTIVE guitar and bass electronics. There is a small PCB inside the control cavity, as well as 1 or 2 9V batteries. This allows the weak signal from the pickups to be boosted a bit, to have tone controls that Boost as well as cut, and also to be able to have alow output impedance so that it can drive the cable to the amp without any problems.

    The signal is not boosted up to the line level of your main preamp - but just enough to eliminate some noise and to drive the cable properly. It must still be close to instrument level or the preamp would not be able to handle it. You see some preamps with high and low level inputs, or input gain controls to handle this.
  4. progrmr


    Sep 3, 2008
    Columbus, Ohio
    Interesting - my first bass (Dean Edge 10a, just shipped today) has Active electronics. So I use my battery and that powers the preamp thats part of the active electronics right?

    sounds sweet!
  5. Active basses typically have a different sound, obviously. There are tons of threads on the passive vs. active argument. It's mostly a personal taste thing. Active isn't necessarily better. Passive provides a more traditional, old-school tone.
  6. ggunn


    Aug 30, 2006
    Austin, TX
    Tone controls on a passive (no preamp) instrument are cut only with "flat" all the way up, while those on an active instrument are boost as well as cut with flat (usually marked with a feelable detent) in the middle. Usually there are three or more bands as well, where passive instruments usually have only one (treble cut) or two (bass and treble cut). That gives you more control over the shape of the equalization coming from the instrument. The signal from an active instrument is hotter as well.

    I love active basses, though some folks don't; I'll leave it up to them to talk about their drawbacks.

    I'll just add that there is a preamp in every stompbox, and the typical amp has several stages of preamplification, so it's really not a matter of having one vs. two.
  7. stflbn


    May 10, 2007

    If that bass isn't specifically setup with an Active/Passive switch it will HAVE to have a 9v battery installed for the bass to work. Batteries last a long time as long as you remember to disconnect your instrument cable from the bass when you're done playing/practicing, etc. Leaving the instrument cable plugged into the bass jack keeps the preamp turned on, so the battery continues to use it's juice. 6-months or more on a 9v is very average, but it really depends on how much you play the bass.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.