Back in 2017 I created an external volume monitor for our Marantz receiver. The receiver is in a cabinet so we can’t see the display on the front, and the on-screen display doesn’t work over 4K inputs. Rather than guess at the volume (to know if you’re going to be blasted out or not be able to hear), I created a little monitor display with an Arduino that kinda did the job.

This is what the original version looked like:

At the time I was pretty good with it. It solved the problem and was… fine.

It’s nine years later and over time I got frustrated with some of the shortcomings. The contrast on the display was never super, so it was always just a little difficult to read from a distance. Combined with my eyes (getting older), it wasn’t cutting it anymore. After a power outage, it was a pain to “recover” because you had to ensure the Arduino was powered up after the receiver or it’d go into a death loop.

Hardware has progressed a lot, so I decided to make an upgrade.

Presenting the new version:

This version has some pretty major upgrades. Built on an ESP32 (instead of Arduino) with a 4” touch screen (instead of a 1602 display), it now has:

• Wi-Fi support instead of wired networking.
• Auto-detection of networks.
• Auto-detection of receivers on the network.
• A nice, large volume display along with a visual gauge.
• Improved display of the source and sound format.
• Full settings menu for reconfiguration, calibration, or checking current connection information.

All still on a budget - the hardware cost about $30.

Here’s the first page of the settings menu:

(Admittedly, the pictures aren’t great… but it’s hard to take a good picture of a reflective touch screen.)

I’ve updated the GitHub repo where all the source is if you want to build one, too. It has all the software, the hardware list, wiring diagrams, even the 3D model I made for the box.