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Total n00b question.

Discussion in 'Amps and Cabs [BG]' started by dajman1800, Mar 4, 2006.


  1. dajman1800

    dajman1800

    Sep 2, 2005
    Seattle, WA
    This is embarassing. :meh:

    I've been wondering for a while, and I've never quite gotten a straight answer.

    What is the difference between a power amp and a pre-amp?
    How do they affect your rig? What are their purposes? :confused:
    What are the options with using them?
     
  2. Jazzin'

    Jazzin' ...Bluesin' and Funkin'

    A poweramp and a preamp work together.

    The preamp is what receives the line from the bass and alters the sound by EQ, sometimes other stuff too, and by its own tone.

    The poweramp takes that sound/signal and amplifies it so it comes out nice and loud out of the speakers.
     
  3. tplyons

    tplyons

    Apr 6, 2003
    Madison, NJ
    The preamp changes the sound.

    The power amps makes you louder!
     
  4. bongomania

    bongomania Gold Supporting Member Commercial User

    Oct 17, 2005
    PDX, OR
    owner, OVNIFX and OVNILabs
    A preamp can sometimes be used to change the sound, but a preamp is really just another gain stage!

    /edit/: the reason they are described (and sometimes packaged) as different/separate things is because it is most efficient to make EQ changes and other tone changes at the relatively low power of the preamp stage, before it gets hugely pumped up at the power amp section.
     
  5. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Maybe this will help?

    [​IMG]

    :D

    Joe.
     
  6. dajman1800

    dajman1800

    Sep 2, 2005
    Seattle, WA
    Alright, sweet.
    Finally set straight :]
    Thanks guys.
     
  7. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    :D

    Joe.
     
  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Technically the preamp is responsible primarily for voltage gain, the power amp primarily for current gain. Both are required to drive a speaker.
     
  9. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Exactly true.

    Bill, has anyone ever call you an egghead?

    (sorry dude, I couldn't resist)

    :D

    Joe.
     
  10. lookjojoisplaid

    lookjojoisplaid

    Oct 17, 2005
    San Diego
    can you run an active bass straight into a power amp?? basically skiping the pre amp
     
  11. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    Sure.

    You can also run a passive bass through a power amp.

    The rub is that your signal going into the power amp will be so small that you get TONS of noise when you turn it up loud enough to be usable.

    It's not as bad with an active bass with the preamp output boosted (I'm speaking of the internal gain adjustment) but you will go through alot of batteries.

    Better to get a preamp.

    But seriously, try it out! You may get lucky! Some power amps can be modified to accept a lower gain signal. QSC comes to mind. This was going on during the big POD/power amp craze.

    The POD Pro was actually meant as a studio effect so the output gain was at a lower level than a regular preamp. Alot of folks wanted to use it to run a power amp so power amps were getting modded.

    :D

    Joe.