Along with Ibanez' Tube Screamer the Boss OD-1 set the standard for tube-like overdriven guitar sound out of a small stompbox. But different to the Ibanez TS-808 the OD-1 features an asymmetric circuit where the positive and negative halves of the waveform aren't distorted equally. Therefore the sound is still close to the original signal even though distortion has been added. The pedal was subject to various changes throughout the eight years of production, whereof replacing the fantastic sounding 14 pin op-amp RC3403 with a dual op-amps (e.g. JRC4558DD) had the most dramatic impact for sound gourmets. On the vintage market it is a matter of $100-$200 whether a long dash and clear switch OD-1 sports a RC3403 or any other chip.