Small amp as Pre-amp?

Probably a stupid question, but can a small amp be installed in a CBG to be used as a pre-amp?  This kind of goes with my previous discussion of using amplified computer speakers as an amp.  What I'm thinking is if I take the PCB guts from a set of powered computer speakers and replace the speakers with an output jack, will feeding the signal into another amplifier boost the volume?  Sort of piggybacking two ampliers?  Or is a pre-amp a whole different kind of circuit?

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  • what you want is a rubyamp kit. if you can solder the you have no problems. as far as i can tell what makes the rubyamp stand out from all those other kits out there - it the only mini "GUITAR" amp out there. All the other kits are just based on circuits from the chip spec sheets and designed for home entertainment i.e playing CDs through them.

    The ruby amp has a proper jfet input buffer stage that has the correct impedance for guitar pickups and can be tweaked for piezo pickups realy easily. the amp is tiny and runs off a 9v battery or wallwart. check it out at www.rubyamp.com

  • I believe you're right.  Just for S&Gs, I tried soldering a 1/4" jack to the speaker leads on the output side of an amp from a set of powered computer speakers.  I then plugged it in between a piezo equipped guitar and different amps I have.  There was certainly a noticeable power boost, but it also added quite a bit of distortion.

    On the plus side, I think the powered speakers will make a nice practice amp.  Will post pics when I convert it.

  • it might work, but i suspect results would be sub-optimum.

    generally, pre amps provide voltage gain but not current gain, and can also shape the sound using filters.

    power amps provide minimal voltage gain, but large current gain to drive the speakers.

    where your computer speaker amp fits into that, who knows?

    at the least, you would have some major impedence mis-match issues, which could seriously suck your tone and/or damage one or both amps (the amp in the box and the guitar amp you're plugging into).

    simple preamps aren't hard to build these days, with only a single chip and a few outboard components - i suspect the effort would be similar and the results much more satisfying.

    e

     

     

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