Psst... Ready to join TalkBass and start posting, make new friends, sell your gear, and more?  Register your free account in 30 seconds.

Newbie question: "Amp" vs. "head"... same difference?

Discussion in 'Amps and Cabs [BG]' started by bassthumpa, Jan 29, 2005.


  1. bassthumpa

    bassthumpa

    Aug 31, 2004
    Austin, TX
    Forgive me for the n00b question, but I haven't been able to get a clear answer searching around on my own. What is the difference between an amp and a head? Are they the same thing, just different terms?
     
  2. Rockland Eagle

    Rockland Eagle

    Jan 29, 2005
    Austin, TX
    "Amp" is a general term. It can mean any sort of amplifier. There are lots of kinds of amplifiers, available in every configuration imaginable.

    One kind of amplifier configuration is sometimes called a stack. A stack has two components: a head, and a speaker cabinet. They stack on top of each other. The head supplies the power to the speakers.

    Another kind of amp is called a "combo." A combo has everything built into one unit.

    If you know anything about guitar amplifiers, Marshall stacks are a head/speaker setup, and an old Fender Twin is an example of a combo amp.
     
  3. bassthumpa

    bassthumpa

    Aug 31, 2004
    Austin, TX
    Ah, just as I suspected, except I always referred to heads as amps (seeing as they're the actual amp unit) and combos as combos. Thanks bro.
     
  4. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    to split it up just a bit more............

    an amp head or "head" contains a preamp and poweramp in one package (as well as eq, and sometimes other stuff like a compressor, DI, etc)

    a preamp in it's purest form has no eq, but bass preamps generally include eq and a DI, and sometimes have a compressor as well. these units need a poweramp to drive speakers.

    a poweramp needs a signal from a preamp to work correctly, and the function of a poweramp is to power speakers.

    speaker cabinets are boxes with speakers in them.

    as said, combos contain everything in one unit. and a stack is a head and cabinet(s). i belive the term stack started to be used around the time the marshall guitar stacks came out. a marshal stack is a head (usually a 100 watt super lead), and two 4x12 cabinets, the bottom one straight, and the top one slanted. when just one 4x12 cab is used it's called a "half stack". Some people call one cabinet and a head a "stack" but to me that sounds a little silly.
     
  5. bassthumpa

    bassthumpa

    Aug 31, 2004
    Austin, TX
    Thanks for the education guys... lets hit the next lesson:

    What is a DI, and what role does a compressor play in this setup?
     
  6. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    a di converts the high impedance signal from a bass into a low impedance signal suitable for sending to a mixing board/pa. on preamps or amps these are sometimes called "XLR outs", "balanced XLR outs" "balanced outs" or "recording outs"

    a compressor is a device for taming the dynamics of a signal. above a certain threshold is "compresses" the signal by a preset or adjustable ratio, (1:3, 1:4, etc). on a 1:4 ratio this means that past the threshold, an increase of 4 dB from your bass only increases the signal going out of the compressor by 1 dB. a limiter is a compressor set to infinite ratio, so above the threshold any amount of signal increase will result in no signal increase coming out of the limiter.
     
  7. bassthumpa

    bassthumpa

    Aug 31, 2004
    Austin, TX
    Thanks again!
     
  8. Cool, I was always not quite sure what it was that compressors do...now I know though!