As the name implies the SD-2 Dual Overdrive has two separate OD circuits. The Lead Mode stock is pretty good actually but the Crunch Mode not so much. There’s also a Lead/Crunch Mode that allows you to switch between the two modes. The concentric pots allow you to have two separate settings for each mode. A foot switch can be used to select either mode remotely.
I have added more gain to the Crunch Mode and tightened up the EQ in the gain. Stock the gain is very compressed and flabby. I have added a 2N3440 Transistor to the Crunch Mode that adds saturation and harmonics.
On the Lead Mode I have added gain and Harmonics. I found the Lead Mode to be way too compressed. After the mod the gain takes on this really saturated harmonic gain that just sings. Not too many pedals offer two gain modes and that makes the SD-2 a very unique pedal. I also offer a cap upgrade for this pedal. These older pedals suffer from caps leaking and going bad over time. Replacing them tightens up the effect and reduces noi
Boss SD-2 MP3 — Recorded using a Strat thru a early seventies Super Reverb and a modded Boss SD-2. I used a variety of Modes and gain settings.