LeoDJ's USB2Speakon Crams an Entire USB DAC and Amp Into a Single speakON Connector

Semi-pseudonymous maker "LeoDJ" has turned an off-the-shelf speakON connector into a fully-fledged USB soundcard — converting any speakON-compatible speaker into a USB-connected sound device.

"It's a fully self-contained, USB-C-powered, two-channel DAC [Digital to Analog Converter] + 5W Class-D amplifier inside a speakON connector," LeoDJ explains of the project. "Use it to connect your phone/laptop to any passive loudspeaker and enjoy surprisingly loud music (probably enough to host a room party)."

The speakON connector was originally developed by Neutrik to offer a higher-current alternative to traditional speaker connections with a foolproof connectivity system and a lock that prevents cables from vibrating loose during use. Typically, a speakON connector sits at the end of the cable connecting an amplifier to a passive speaker — but in this case, the speakON connector is the amplifier thanks to a custom PCB that includes a DAC, an amp, and a USB Type-C connector.

"After a few design iterations, I had a working design for a shell that securely holds the USB2Speakon PCB in the back of the plug," LeoDJ explains. "The shell fits snugly and keeps everything together even without the outer housing screwed on. I also bodged on a 470uF capacitor as a tiny energy buffer, I think it helped a bit with clipping, but obv. not too much. And with that the first prototype was done™."

In testing, the USB2Speakon — which fits entirely in the speakON connector, flush against its rear — was able to deliver volumes loud enough for what its creator estimates would be a "small indoor party." The initial prototype, though, has a few issues — including its use of a now-discontinued speakON housing, quieter volume when connected to Android phones than a PC, and the wrong footprint for the required 6MHz crystal, to be fixed in a future revision.

The USB2Speakon is available on LeoDJ's GitHub repository under the Weakly Reciprocal version of the CERN Open Hardware License Version 2, though its creator warns that "it's not recommended to reproduce this project in the current state, as v0.1 contains some issues and v0.2 is not yet tested."

More information is available in LeoDJ's Mastodon post.