As described in THIS POST, BYOC has redesigned their very popular Overdrive kit (Tube Screamer TS808 circuit clone), adding a number of new features and options. It even includes an integrated booster section that functions indepedently from the OD circuit and has it's own separate stomp switch. But the feature that grabbed my attention right away was the ability to build it as a MOSFET overdrive. If you're into overdrive pedals, you'll know that MOSFET-based OD's are all the rage, for their natural, tube-like response. The well regarded "boutique" MOSFET OD's regularly command prices in the $200 - $300 range. You've probably heard the names--Hermida Mosferatu, Fulltone Fulldrive 2 MOSFET, Blackstone MOSFET Overdrive, etc.

I already have a modified TS808 clone (IMO, one of the best you'll find--my Zonkin' Yellow Screamer mod!), but building a MOSFET version was something I definitely wanted to try. I managed to get two out of a handful of kits that Keith at BYOC still had available after his distributors ran him out of most of the initial production run. They were delivered this past Monday. One is for a Fretter who wanted one of these as a gift, but the other--that puppy is MINE!!

Looking through the build options, it turns out that MOSFETs can be used in 5 different places in this circuit:

  • The input buffer
  • The opamp
  • The clipping stage
  • The output buffer
  • The boost stage

I did some looking into the pro's & con's of using MOSFET's in these various parts of the circuit and decided to go with them everywhere but the output buffer--sticking with a bipolar transistor there apparently gives the pedal better drive characteristics. The input buffer and clipping section will have the MOSFETs soldered in. The pedal comes with an opamp socket, so I'll start with the MC33502 dual-MOSFET opamp provided in the kit, though it also includes a JRC4558D and a Burr Brown OPA2134. And I decided to socket the entire booster section of the circuit (it's only 8 component spots), so that I can try both MOSFET and bipolar NPN trannies there, as well as play with the max. boost gain. The MOSFET is supposed to give a very clean, chimey boost, where the bipolar NPN will provide more drive and a slight degree of distortion. So I'll see which I like better, both alone and in combination with the main overdrive stage. Should be fun, mixing & matching.

Anyway, I started the build a couple of nights ago, and have it all together except for the jack and switch wiring, plus adding all the socketed components. Hope to finish it up tonight, 'cuz the rest of the weekend looks pretty well packed with family commitments. Will take some pics to post here, as well as the obligatory sound clip, once I've had a chance to play with it some and explore the sonic possibilities....