CHWTT's Second-Generation Fader Deck Is a Slick Way to Handle Per-Application Volume Control
From its aluminum chassis to motorized faders with memory function, this mixing deck means you'll never be deafened by notifications again.
Pseudonymous maker "CHWTT," of the Computer Hardware Tips and Tutorials YouTube channel, has built a chunky controller designed to make it easier to adjust the volume of individual applications on the fly — with motorized sliders so their position reflects the current setting in software.
"Back right at the end of December last year, I posted a video about a project that ended up garnering a load of traction - so much so that I got a ton of views considering what my channel usually gets," CHWTT explains of a previous incarnation of the volume fader. "Basically, with this device you could bind YouTube to a fader, Spotify to another, your games to a third, Discord to a fourth, and your main output level or something to the fifth. Then you could use the faders to control the level of each app individually."
Per-app audio control provides an easy way to balance levels between different applications — decreasing the volume of background music playing in a streaming app while boosting an audiobook, for example, or muting the notification sounds from a messaging app while keeping email notifications active. While most operating systems offer a software-based method for handling this, CHWTT opted for hardware — building a physical volume control box with multiple faders.
In the revised and upgraded version, the Teensy 4.1-powered device offers five motorized faders — adjusting the position of each according to the volume currently set in software. While that was also a feature of the original build, in this revised version the motors are under proportional-integral-derivative control for smooth motion and more accurate positioning. Each fader also receives a dedicated OLED "scribble strip" at the top, identifying the app it controls and the current volume setting, and there are physical mute buttons for each for quick silence.
There are another eight buttons, too, and these provide a memory function: "If you have a set mix that you want to save, choose which of the eight slots (represented by the eight buttons on the right side) you want to save the mix to," CHWTT explains. "Hold the button you want to save the mix to for two seconds, and then let it go. You should get a message indicating the preset was saved to that slot, and now when you short press that button, the faders will zip right to the positions you saved in that slot."
CHWTT has detailed the project on Instructables, complete with code and a full bill of materials; Gerber files for the custom PCB are available on PCBWay under the reciprocal Creative Commons Attribution-NonCommercial-ShareAlike license.