Boss DS-1 with Keeley Seeing Eye (SEM)

Keeley Electronics Boss DS-1 SEM was designed to correct the originals shortcomings both in tone and distortion quality. The intention of the DS-1 SEM was to not only increase the amount of gain available, but also make it usable, smoother gain through careful tuning of the tone control network. Beyond tuning the DS-1 SEM for better tone through new values of parts, many of the original units parts were discarded and substituted for premium components such as tantalum capacitors. To increase initial gain, Keeley incorporated a unique diode in the circuit, which doubles as the "Seeing Eye". As notes or chords are played, the light-emitting-diode flashes and pulses with equivalent intensity as your guitar signal. A cool look certainly, but very useful ? in fact, this type of clipping is used to help "gain up" even the most famous of amplifiers such as Marshalls Jubilee series amps, first introduced in 1987, and reissued in various forms since then.