This PCB allows you to build an exact replica of a Maxon OD-820 Overdrive Pro. Due to the circuit’s relatively high parts count, it was pretty tough to fit everything into a 1590B enclosure, so this PCB does not include any modifications such as a clipping switch or pads for extra diodes.
With its 18v charge pump and dual-pot “gain/blend” control, the Maxon OD-820 Overdrive Pro actually shares a lot of concepts with the Klon Centaur—and they are often compared with one another in sound. But it is by no means a clone. The OD-820 is actually a little closer to a Tube Screamer with regard to its clipping diodes and tone control. (Check out this Legendary Tones article from 2004 comparing the OD-820 with the Klon Centaur.)
The OD-820 is the same circuit as the VOP-9 Vintage Overdrive Pro. The OD-820 has a larger enclosure that matches the other Vintage Series effects such as the DS-830 Distortion Master, while the VOP-9 is housed in the smaller standard Ibanez enclosure.