Episode 051: Amped Up

Learn more about how a preamp and power amplifier boost your sound in different ways.

Show notes

Have you ever used separates for preamp and power amplifier? If so, what was the setup?

  • Dave
    • No
  • Paul
    • Yes, episode is over 😄
    • Line6 Bass POD Pro → Mackie power amp
    • Studio: Avalon U5 → board

Where do I find preamps?

  • Most instrument amplifiers have one
    • Preamp section where your instrument plugs in
    • Power amp comes after the FX, EQ, any comp/limiting, etc.
  • Dedicated preamps — rack or desktop
  • You can get preamp stomp boxes
    • Some DIs can function as a preamp
    • Dave — SansAmp
    • Multi-effects pedals usually can function as preamps too
  • Can’t power speakers with just a preamp
    • But you can run the preamp into an active speaker and it will work, because an active speaker has its own power amp!
    • Just not passive speakers

What makes it different from a power amp?

  • A preamp is just an amplifier to get the very weak instrument signal to a signal that’s strong enough to be fiddled with.
  • But not strong enough to drive speakers, which takes quite a lot of power.
  • Helps the signal resist noise as you apply processing to it (like EQ, compression, etc.)

What happens if I’m using a pedal that works as a preamp, and running that into my amp head’s preamp section (instrument input)?

  • You may be effectively boosting the signal twice
  • Often the resulting sound will be clipping or at least distorted before it hits EQ, FX loop, or anything else, or the preamp
  • However, some amps have a preamp “gain” control separate from the power amp volume
  • You may be able to compensate here, just like you compensate for a louder active bass vs. a passive one
  • This can be touchy — if you preamp elsewhere, better to come into the FX return as an already line-level (somewhat amplified) signal.

Why preamps make better recordings than plugging your instrument straight into an interface (usually)

  • Because the preamp boosts the signal, you can lower the gain on the interface
  • This means less intrinsic noise from both your bass and the interface itself
  • Some interfaces offer an instrument level that sets a built-in preamp at the right level

Are there benefits of having separate preamp/power amp?

  • Mix and match convenience
  • Preamp you can carry to recordings
  • If one piece goes, the whole unit isn’t useless

Photo by Leo Wieling on Unsplash. Music: JahzzarPlease Listen CarefullyspinningmerkabaUrbana-Metronica (wooh-yeah mix).

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