The OD-1 was one of the first overdrive pedals, introduced in 1978. Boss material states that the SD-1, introduced in 1981, was basically a sliughtly tweaked OD-1 circuit with an added tone knob. Since a lot of the discussion here revolves around the fact that the SD-1 circuit is virtually identical to the Tube Screamer circuit, does that mean that the OD-1 circuit is also similar to the TS? I thought the OD-1 was a completely different design, and certainly sounds different to my ears. Also, I've also read that the OD-3 is based on the OD-1 circuit. Yeah, I know not to believe everything i read, especially on the internet, but are their any connections among and between the OD-1, SD-1, OD-3 and TS circuits/sounds/etc.?