Volume Limiter Dongle

The dongle in its final clear enclosure held between my index finger and thumb. A blob of hot glue is visible on the plug side.

What Is It?

For some reason Android’s settings for volume force me to hide in the bottom 1/4 of the volume slider with my headphones. Sometimes even the lowest setting is too loud. It’s even worse for phone calls because Android forces the volume to be boosted to a level that hurts my ears on even on the lowest setting.

The Crafts Side

So I decided to make this. I ordered the input and output halves of a headphone jack and soldered what I needed in between. I used head shrink tubing to prevent unintended contact between the different wires. In order to protect the dongle while I’m out and about, I added some holes to a plastic jar from the dollar store and stuck it inside. I had to use some hot glue on the plug end because the jar was a little bit too short to fully house the device. In the end, it’s somewhat reminiscent of a vacuum tube, which I think is pretty neat.

The Technology Side

I added a 56 Ω resistor on each audio channel and two wires to connect the ground and microphone directly from one side to the other. This raises my headphones’ impedance from 24 Ω to 80 Ω. The volume is quieter, and there’s less noise from electrical interference. The output on my phone is supplying the same amount of power, but the resistors end up soaking up 70% of it, meaning that only 30% of the full power ends up reaching my the headphones.

The dongle is shown connected between a USB-C audio adapter and a pair of 1/8 A side view of the exposed connections with one blue resistor partially visible. A 360° view of the bare wiring of the dongle. Heat shrink tubing mostly obscures the resistors. An angled view of the dongle that show’s the headphone socket as well as some of the exposed wires.