Rgba

rgba - reasonably good bluetooth audio

The rgba is a tiny (41x20mm PCB), extremely high fidelity Bluetooth audio receiver meant to attach inline to the cord of a pair of IEMs. It aims to provide as high quality audio as possible while retaining reasonable battery life and its small form factor. It is designed to pair well with high sensitivity, low impedance IEMs. For use with lower sensitivity, harder to drive headphones (or IEMs), you'll need to adjust the values of the resistor feedback network around the Op Amp to provide the proper output power. See this document, especially sections 1 through 3, for more information. Reach out to me via GitHub issue or social media (listed on my GitHub profile) and I'd be happy to guide you on this.

Schematic

See rgba.pdf for a PDF copy of the schematic, or open the repo's root as a project in KiCad and launch Eeschema.

Renders

Here are a couple of renders of the latest version of the PCB.

Bill of Materials

A bill of materials is available in HTML format, with links to sourcing information and interactive PCB board view useful when performing assembly. View it here: https://termhn.github.io/rgba/ibom.html

Not included in the BOM is a battery. You can use any single cell LiPo (3.7V) LiPo battery up to 500mAh in capacity. You'll likely need to either re-terminate the batteries with the proper connector (2-pin JST-ACH plug housing and crimp leads can be found on DigiKey) or lop off the included connector and solder the leads directly to the board.

PCB Sourcing

I recommend ordering PCBs through OSH Park because their 4 layer process has the needed precision at a reasonable price (JLCPCB for example will cost you a lot more to get the needed 0.2/0.4 diameter vias), is good quality, and are a cool organization to support. Plus their PCBs are a super purdy purple :d

You can order some of the rev 1.1 PCBs directly using this link: -link will be inserted here when it has been tested working-