If you've ever listened to digital music with high-quality headphones and found yourself disappointed with the sound quality, it was probably for one of two reasons: the file was encoded with lossy compression or you didn't use a good DAC. The DAC (digital-to-analog converter) is the component that turns digital ones and zeroes into nice, smooth analog wave forms. Without a DAC, a computer can only output a square wave — turning the signal on and off at specific frequencies. Because it is so important, the open source Ploopy headphones integrate an RP2040-based DAC.
Most modern computers have built-in soundcards with their own DACs, but their sound quality is often poor. For that reason, many people buy dedicated DACs that connect to their computers via USB. The Ploopy headphones follow that setup, connecting via TRS (Terminal Ring Sleeve) cable to the amplifier box containing the DAC, which connects to the user's computer via a USB cable. The amplifier box is nice and slim, so it won't take up much room. But it provides six-band EQ with a 48kHz, 16-bit audio stream for high fidelity sound.
Unlike many DIY headphones that simply use off-the-shelf drivers in custom cups, the entire Ploopy design is original. The user builds everything from the drivers to the headband. To keep costs down, the amplifier box uses an RP2040 microcontroller (the same as in the Raspberry Pi Pico) for the DAC and DSP (digital signal processing). That required some clever mathematical workarounds, as the RP2040 doesn't have a dedicated FPU (Floating Point Unit) and is therefore slow to process floating point math. But by converting all of the calculations to fixed point math, Ploopy's designer was able to take advantage of the power and affordability of the RP2040.
If you want a set of Ploopy headphones, you have a few options. The design is fully open source, so you can grab the files from the GitHub page and make everything yourself. If you want to save yourself a lot of time and work, you can pre-order a kit that contains all of the components you need (including the 3D-printed parts and amplifier board). Or you can pre-order fully assembled Ploopy headphones. There are different pre-order tiers available with varying lead times, so be sure to read that information on the Ploopy website before you place an order.