Loser Question: What is a preamp?

Discussion in 'Miscellaneous [BG]' started by fleabass89, Mar 14, 2001.

  1. I believe it's something that you run your bass output through before the amp, but I don't know why. Am I right??
  2. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    A preamp is a stage in the signal chain (not necessarily a separate piece of gear).
    The main purpose is to amplify the sound signal from instrument level up to line level. Along with that the impedance changes from high to low level (this can also be achieved by a FX stomp box or a line buffer - that's why active basses have a low impedance, passive basses have high impedance (because the pickups themselves usually have a high impedance, and the active circuit makes it low impedance).
    High impedance can cause loss of highs when the signal travels the instrument cable - that's one of the reasons why an active bass seems to offer more highs and a brighter over-all sound. The amp input should have a 10-fold higher impedance than the signal source plugged into it to avoid misalignment (I hope I remember correctly and excuse my poor technical English).
    Some active basses have such high-level (and low impedance) output that you can plug them into a poweramp without using a preamp.
    Most (bass) preamps offer additional functions such as EQ, built-in FX, FX loops, etc.
  3. Thanks for all the help!
    correct me if I'm wrong but heads are preamps and poweramps in one, right? Because I think I saw that somewhere. But I have another question: what's a poweramp for? And what the hell is an ohm? I've seen that word a million times.
  4. Yes

    To make the sound louder. The preamp shapes the signal, EQ, effects, and other noises, then the power amp <b>amplifies</b> them so they are louder, then the signal goes into the speakers.

    Ohms are units of resistance. Most of the time when you see "Ohm" it will be in relation to speaker cabs. Basicly, an amp can run into one 4 (or 2) ohm cab, or 2 8 Ohm cabs. 2 8 Ohms make the amp think it's driving a 4 Ohm cabinet. Basicly, divide by two if you have more than one cab to see if it's a safe load (it will say what load your amp can drive on the amp).

    Hope I've helped, but probably not.
  5. Munjibunga

    Munjibunga Total Hyper-Elite Member Gold Supporting Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    You're not a real loser. Real losers spell it "looser."