Portable Modular Audio Player


First, a brief rant about Apple’s AirPods:

I have two pairs of Apple’s 2nd Gen AirPods and the first pair is ready for the bin. Why? Because Apple has engineered these devices to be discarded once the battery (inevitably) dies. Am I supposed to just smile, shrug and give iStore another R3 000? Apple thinks I’m loaded or dumb (or both). However, I’m neither.

So instead, I’m waving bye bye to my AirPods and switching to something more sustainable to my wallet (and, as a possible side effect, the Earth).

sexy. minimal. e-waste. (Image Credit)

AirPods (and most wireless headphones) have at least the following 5 systems:

  1. Audio Driver
    • Convert electrical signals to sounds you can hear
  2. Processor and Communication
    • Run audio software and manage Wireless connections (eg. Bluetooth)
    • Passes digital audio signals to D to A System
  3.  Digital <-> Analog
    • Converts Digital Audio to analog signals for Audio Driver
    • Converts analog signals to digital for Processor
  4. Battery
    • Control Battery Charging, discharging and protection
    • Provides power to all systems
  5. Audio Input
    • Converts sound to electrical signals

In a single AirPod, all these systems are designed in a tightly integrated manner..

Image via iFixit

..which means you can’t individually repair, replace or upgrade individual components. If any part stops working, it’s all gotta go in the bin.

So I’ll be taking the opposite approach by having separate, modular components:

  1. Audio Driver
  2. Processor and Communication system
  3.  Digital <-> Analog System
  4. Battery System

Since it’ll be 100% audio consumption, I’ve left out the audio input (microphone) component.

Setup Guide

All the ingredients to make a tasty sandwich

Note: Photos show a Zero W. It was switched out for a Zero 2 W but I wanted to keep the photos 🙂

First, set up the UPS HAT. Being paranoid about the closeness of of the pogo pins, I slotted some insulation tape between them.

Then follow the important steps in Waveshare’s guide and leave it aside to charge.

Next grab the Pi and follow and the moOde installation guide, inserting Pimoroni’s steps after flashing the SD. Once that’s done, you should have the Pi and Pirate Audio HAT set up, AirPlay working and powered by USB. (Note: If you’re coming from GitHub, this is an optional step. I like running known-working software to make sure my hardware working as expected before testing something more experimental.)

Ideally by then, the UPS is ready to output some power, so you can connect them all together and test:

The best sandwich tastes like Pi

Testing and Thoughts

Not unexpectedly, it works! It also ends up resembling the Bluetooth Headphone AMP/wireless DAC form factor (eg. Qudelix 5k / ifi Go blu / FiiO BTR5) just a bit bigger. The difference, of course, is that I can freely switch out my DAC, Raspberry Pi or battery. Oh, and this supports lossless audio over AirPlay 2 which no Bluetooth DAC can match.

Clearly, this is a very “alpha” setup. I can use AirPlay 2, Bluetooth and all the other moOde features but there are some obvious issues. The backlight is always on but there’s nothing on the screen. The buttons are unused, there’s no way to see the battery remaining, etcetera etcetera.

However, this is just the beginning…

The Future

Although I started this project because of my rage against the AirPods, it’s now morphed into something more. Since it has a screen, buttons, WiFi, Bluetooth and plenty of processor power, I want it to feel like a real product, not just something hacked together.

Also, instead of starting with moOde and tacking on support for the screen and battery (moOde natively supports GPIO buttons), I want to write the software that drives the main features I want to have. Naturally, I’ll also be utilizing numerous open source projects along to the way to perform some of the heavy lifting.

All the code I’m writing is available on GitHub with a nice install script so you can join in on the fun too. I also need to design an enclosure.. Stay tuned for part 2 of this series!

If you have any questions/would like to share your experience with DIY portable audio projects, leave a reply below. To receive an email when I publish a post, subscribe here.

(Featured image remixed from this photo)

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Proudly powered by WordPress | Theme: Baskerville 2 by Anders Noren.

Up ↑