Commercial cassette adapters — the ones with a 3.5mm cable trailing out of the shell — worked by feeding audio into the tape deck’s read head, using it in reverse as a kind of write head. Jonathan Rowny has built the logical next version: the same trick with the music source inside the shell, so the cassette is the player.
The build
- ESP32-S3 running everything
- microSD reader holding the music
- PCM5102 I2S codec converting digital audio to the analogue signal the head expects
- Audio delivered through the deck’s read head, exactly as a commercial adapter does
- SLA-printed gears transferring motion between the take-up and supply spools
The gears are the clever part
Here’s the problem that makes this more than a battery-and-a-board exercise. A cassette deck is a mechanical system that watches the tape to know what’s happening. If the spools stop turning, the deck concludes the tape has ended and fires auto-stop, or flips to auto-reverse. A cassette-shaped object with nothing moving inside it gets ejected within seconds.
So the printed gears exist to convince the transport that a tape is running. They detect and transfer motion between the spools, keeping the deck’s sensing mechanism satisfied while no actual tape exists. That’s reverse engineering of the most satisfying sort: not defeating a protection mechanism, but politely giving a 40-year-old machine the feedback it was designed to look for.
Rowny is candid about the gap: he didn’t account for capstan motion, the part that actually pulls tape past the head, and expects to address it in a later revision. Work like this is a sequence of discoveries about what a mechanism is really checking.
He credits Clint of Lazy Game Reviews, whose teardowns of commercial cassette adapters supplied the groundwork.
Why it’s worth attention beyond the novelty
Two reasons.
It’s a study in interfacing with hardware you can’t modify. Everything here is about meeting an existing machine’s expectations — its head, its sensing, its transport — rather than changing it. That’s the same discipline required to put new work into old equipment of any kind, which is a recurring problem for artists using obsolete media.
It makes tape decks a usable output device again. There are a lot of working cassette decks in the world, in cars, in boomboxes, in studios, and they all have a physical presence that no Bluetooth speaker has. A drop-in digital source turns any of them into a playback device for new work, with the deck’s own wow, flutter and tape-path colouration applied on the way out — which some people pay for in plugin form.