I'm looking to make something fairly small, simple, and portable. I would like something that I could use as a guitar amp but could also play some music through when I'm out in the shed(I work on my tractor and go kart in there). I would like for it to be small, but still sound decent. I don't know if maybe I'm asking too much though. If it is possible could you point me in the right direction as to where to start with it?
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Wall plug, USA voltage, preferably solid state.
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I've heard people getting good results out of a Class D amp from ebay. Here's a cheap stereo one rated at 25W per channel: http://www.ebay.com/itm/TPA3123-25W-X-2-Dual-Channel-Class-D-Digital-Audio-Power-Amplifier-DIY-/280998720604?pt=US_Home_Audio_Amplifiers_Preamps&hash=item416cd4345c

Then you could use any of the preamps turned stompbox at runoff groove for the guitar preamp: http://www.runoffgroove.com/articles.html

You'd have to build a phase inverter to get the most out of both channels, or you could just use one side. Wire up a switch to bypass the preamp when you plug in your MP3 player into it or use the other channel for that purpose.
Which of those pre-amps could I use, it seems like the ones he has that were meant for that kind of thing were the eighteen, the english channel, matchbox, and an omega, I'm thinking I might use the eighteen for the guitar channel at least(given that its applicable) and the omega for the MP3 channel because it seems like it wouldn't color the tone too much.
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Last edited by Viban at Oct 17, 2012,
That's pretty helpful, thanks. But would the eighteen be good as the pre-amp for the guitar channel or does it output too much?
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You can control the output since it has a volume control at the end. Really, any of the following Runoffgroove projects would work:

Azabache (Fender)
Eighteen (Marshall 18)
The English Channel (Vox AC30)
Ginger (Ampeg Portaflex)
Matchbox (Matchless DC30)
Mockman (Rockman)
Supreau Deux (Supro 16T)
Thor (Marshall Plexi)
Umble (Dumble)
Uno (Mesa/Boogie Mk1)
Well I figured those'd be the ones that would work, this one I'm going with the eighteen, maybe if I like the way it turns out I'll make the dumble or the plexi.
Quote by R45VT
It'd be cool if you made it similar to how Egnater does its modules. That way you could swap preamps in and out as you see fit.

As for powering this thing, you've got a couple options. I recommend just using a laptop power supply or a wall wart. Something about 15 volts for the poweramp. And then you could just use a 78L09 voltage regulator to bring the voltage down to 9 volts for the preamp. Although, I'm not sure if there are many wall warts that will supply 4 to 5 amps. I'll look into it real quick.

EDIT: Like I said, it was a very quick look, but I found this supply that would work: http://www.amazon.com/Replacement-Adapter-Toshiba-Satellite-Portege/dp/B005LCTOGI/ref=sr_1_5?s=electronics&ie=UTF8&qid=1350529891&sr=1-5&keywords=wall+wart+15v
Last edited by end_citizen at Oct 17, 2012,
I might do that, find a way to wire it in with a something like a usb port where I could just slide them in and out of a compartment. It would probably not take much more work.
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I might do that, find a way to wire it in with a something like a usb port where I could just slide them in and out of a compartment. It would probably not take much more work.

USB sounds like a good idea since you'll really only have 3 connections going to the poweramp - Positive voltage, Ground, and Signal.
Wouldn't you need a ground for the power circuit, and then one of the signal? Or do you just tie the two together? Either way I figured it'd be perfect seeing as USB is configured pretty much the same way.
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You can usually tie signal ground and power ground together.

Good things to know right there, could really help clean up my wiring a whole load.
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