The Refractor Professional Overdrive is a clone of the Klon® Centaur Professional Overdrive and its successor, the KTR.
While the original Centaur was buffered bypass, the newer KTR added the option to switch between buffered bypass (called “Almost Always Better” by the designer) and true bypass (called “Almost Always Worse”). There were an overwhelming number of requests for this to be added to the Refractor, so this updated version implements the switch.
As of its release, the Refractor is the only DIY version of the Centaur or KTR that uses the correct true/buffer switch wiring from the original unit. Several other projects use a simpler wiring method that does not preserve the original circuit in buffered mode, which was one of the inventor’s stipulations.
Aside from the addition of the true bypass / buffer switch, the KTR is identical to the original Centaur circuit except for two components:
- A pulldown resistor, RPD, has been added to counteract switch pop in the true-bypass mode.
- R2 has been changed from 1M to 2M so that the input impedance stays the same with the addition of RPD (since two 2M resistors in parallel make 1M, which was the original value).