The 808’s bridged T network

The iconic Roland TR-808 kick drum spawned entire genres. You may not be aware, though, of the clever electronics that make its distinctive sound.

Widely believed to be a collaborative effort between Roland founder Ikutaro Kakehashi, chief engineer Makoto Muroi and a hardware engineer named Nakamura, the 808’s innovative circuit design created unique sounds. The kick drum is a perfect example.

The 808 bass drum circuit is based around a ‘bridged T network’ oscillator. Rather than oscillating continuously, the bridged T oscillates when triggered and decays down to silence on its own, without needing to be modulated by envelope generators and VCAs. Decay time can be adjusted using positive feedback, while the osc pitch also drops slightly at the end of longer decay times.

In practical terms, the bridged T network oscillator is what defines the 808 kick: distinctly pitched, with a characteristic decay curve and a small change in frequency over the length of its decay tail. There are other ways to get such sounds, but the TR-808 designers’ creativity helped to define a legend.