3. Connect the input jack
Now it’s soldering time. First, get both cables inside the opened box and simply snip off or desolder the unneeded cable for the second box. If you are using the stereo setup, get only the presoldered input cable inside the box and don’t snip off the second speaker's cable! Solder the two twisted hot leads of the input cable to the tip of the jack and the two twisted blank mass leads to the sleeve. After you've finished this step, it should look like this:
4. Fine-tuning the amp
Believe it or not, that’s it! Plug in your axe for a preliminary test. You will likely discover that the amp is working, but that it suffers from a poor output level. This is because of the mismatched impedance – PC speaker systems are designed to work with a pre-amplified signal from your soundcard, not a passive guitar signal.
The best solution is to trace the first resistor on the PCB after the input and desolder it or snip it off, if possible. With that complete, you can take full advantage of the system’s built-in amp, with more than enough volume for bedroom playing. You can also use the headphone output for silent playing if your speaker system offers such an option.
If you’re not interested in tracing resistors, you could also consider using a booster or buffer in front of the box to boost the signal and/or change the signal’s impedance. It isn’t the most elegant solution, because you’ll have to carry another box with you and the main goal is to have a small and handy practice amp for your next journey, but it is something to consider.
So with a few quick solders, you have a portable practice amp, just in time for the holidays. It won’t sound like a cranked Marshall stack, but at least it offers a great clean tone to practice your skills, wherever you are.
Have a great one and I will see you next month!
Dirk Wacker has been addicted to all kinds of guitars since the age of 5 and is fascinated by anything that has something to do with old Fender guitars and amps. He hates short scales and Telecaster neck pickups, but loves twang. In his spare time he plays country, rockabilly, surf and Nashville styles in several bands, works as a studio musician and writes for several guitar mags. He is also a hardcore DIY guy for guitars, amps and stompboxes and also runs an extensive webpage singlecoil.com about these things.