Bitcrusher
An effect that deliberately makes digital audio worse, throwing away the bits and samples engineers once fought hard to get.
Two knobs do the work. One lowers the bit depth, rounding the signal to coarser steps until quantisation noise becomes an audible fizz. The other lowers the sample rate by holding each value for several samples — without the filter that normally guards against anything above the Nyquist frequency. The result is aliasing: false, often inharmonic tones folded back down into the audible range.
It sounds like early samplers and game consoles, which is the whole point. The E-mu SP-1200, with its 12 bits and roughly 26 kHz, shaped the sound of late-eighties hip-hop drums, and the chiptune scene is built on the same limitations. The irony is hard to miss: decades of research into dithering and oversampling, and then people pay to get the noise back.