I just read the MP3 Player Shield Music Box Tutorial (found at MP3 Player Shield Music Box - SparkFun Learn) and I wanted to make sure I understand something correctly before I buy any parts. I'm hoping to build a music box so I thought this tutorial would be a good place to start. In the tutorial, they use an Arduino Uno - R3, a SparkFun Mono Audio Amp Breakout - TPA2005D1, and a SparkFun MP3 Player Shield. However, I'm hoping to make my music box quite a bit smaller than the tutorial, so I was looking at their suggestion to instead use a Arduino Pro Mini 328 - 3.3V/8MHz and a SparkFun Audio-Sound Breakout - WTV020SD. From the way I understand it, the Mini takes the place of the Uno and the Audio-Sound Breakout takes the place of the Mono Audio Amp Breakout AND the MP3 Player Shield. Is that true? Would I just need a Mini (with a SparkFun FTDI Basic Breakout - 3.3V to program it), an Audio-Sound Breakout, a small speaker, materials to wire everything together, and a micro SD card to get my project to play any song on the micro SD card through the speaker at a loud enough volume to easily be heard? I know I would need to program it, but is that all the hardware I would need or am I missing something? Also, any additional suggestions/insight for this project would be greatly appreciated. Thank you for any help you can give.
Whether you use an uno or mini doesn't matter much, both are equipped with the same microcontroller.
If you only need a standard set of songs/sounds to be played a WTV020SD could... replace an MP3-shield.
As far as I understand, the module expects files to be in a specific format though, which can be very annoying. It requires you to convert every song/sound before you can play it.
Loud... is probably a matter of opinion, it will be loud enough to be heard, but for a bit of volume you'll need to add a small amplifier.
A shield or shield-size arduino can indeed be to big for some projects, but you don't have to use arduino-sized modules.
Just check which chip is most important, search for modules that use it and other usable modules will pop up.
The official MP3 shield uses a vs1053 chip for example, just like this module which is a bit smaller.