MP3 player too quiet when you hook it up to your car’s Aux-In or home stereo? Make it louder with the Opa! Amp.
The Opa! Amp is an USB powered audio pre-amplifier based on a Burr-Brown OPA2227. With 0.00001% total harmonic distortion, it’s a high quality way to make your MP3 player louder when hooked up to your home or car stereo.
This project is suitable for beginners, you'll need a few soldering tools, but even if you've never soldered before, it's an easy build. You can etch your own board, make it on a protoboard, or pick up a kit from Gadget Gangster
I made the Opa! Amp because I recently got a smartphone – it sounded great with headphones, but when I hooked it up to my stereo, I had to crank up the volume to hear it and there was distortion. Listening to spoken word stuff in the car was the worst. The Opa! Amp increases the audio level and fixes the problem without distortion.
The next few steps discuss the design and testing process. If you just want an awesome pre-amp, skip to Step 6: Making It.