We'll go over each pin on the board in the next page, right now let's look at the basic elements of the Sound Board so you have an idea of what each piece does.

Starting from the left is the micro B USB jack. You'll need a standard Micro B USB cable to connect this to your computer. You do need a computer (any will do) in order to save files onto the Sound Board flash storage

This big chip is the audio decoding engine. It has OGG and WAV decoding capability and can listen to the trigger pins to know when to play each file. It has great audio quality, much better than trying to have a microcontroller generate the audio on its own.

It cannot decode MP3 files - but that makes it a lot less expensive since MP3 decoding requires a patent license where as OGG and WAV are free for any kind of use.

This is the onboard flash chip. It's basically like a little SD card, but soldered directly onto the PCB. These chips can store a few megabytes. This doesn't seem like much but for most audio effects, you don't need hours of music. You can store a couple minute's worth of compressed OGG on a 2M flash chip.

Headphone Output Type

All the way to the right is the headphone jack. This is for connecting to a pair of headphones or into a powered speaker. It cannot drive an 8 ohm or 4 ohm speaker. Instead, an amplifier will have to be used (basically, just like your phone or pocket MP3 player needs an external powered/amplified speaker)

The outputs are 'live level' (about 1Vpp) and have DC blocking capacitors so it can be connected to any kind of amplifier.

Stereo Amplifier Type

All the way to the right is the Class D stereo amplifier. This is for connecting to a pair of speakers! The outputs are bridge-tied-load (BTL) so do not connect R+ to L+ and R- to L- to get more power, it could damage the chip. If you only need one speaker, simply connect the channel you want.

The amplifier can drive 8 ohm or 4 ohm speaker, up to 2.8W (10% distortion, 4 ohm) and 2.2W (1% distortion, 4 ohm)

4 ohm speakers will be louder than 8 ohm

Powering from 5V will be louder than 3V, so if you need more oomph, you can power from 4 x AA rechargeable batteries, or 3 x AA Alkaline, or a USB battery pack. It's pretty damn loud tho!

This guide was first published on Sep 23, 2014. It was last updated on Sep 23, 2014.

This page (Tour) was last updated on Oct 25, 2023.

Text editor powered by tinymce.