making an original BOSS DS-1 clone, single op-amp

[jokersmile32]

I want to make a clone of the original, oldest version of the boss ds-1.  i see a lot of schematics for the dual op-amp version, and a few schematics on a single op-amp version, but some of them have a transistor before the IC and other versions do not.    Im going to be making the pedal true bypass so I dont need the switching circuitry/input buffer, but i would still like to see how that part works too.  has anyone traced a vintage boss ds-1?

[WGTP]

http://www.diystompboxes.com/DIYFiles/up/Build_Your_Own_DS-1_Distortion.pdf