OKKO - Diablo Boost+

Here's another personal favourite of mine. I just love those ridiculously sized LEDs! Anyway, the OKKO Diablo Boost + was donated to the freestompboxes forum anonymously. It's a great sounding overdrive/booster that when combined with the extra "+" knob can venture into some pretty high gain territory.

Here's a description from the OKKO website:

"The Diablo is a versatile low to medium gain overdrive with an exceptionally dynamic response. It preserves the character of your instruments and is very sensitive to your playing technique. Thanks to the effective and musical controls, the Diablo works equally well with any kind of guitar,  amp or playing style. People use it for so many different sounds, you would hardly believe that they use the same pedal.

Besides the usual Gain, Tone and Level knobs, the Diablo has some more interesting controls:
FEED affects the amount of bass in the input signal. You know the problem: an overdrive sound gets muddy rapidly if the input signal is too bass heavy (that’s why the treble booster was invented). With the FEED control you can make even the fattest neck humbucker sound clear and transparent or beef up weak pickups a little.
The BODY control takes effect on mids and compression. Another important feature is the HEADROOM SWITCH. Set to the "HI" position, an internal electronic voltage doubler is activated – the Diablo runs on 18 Volts from a regular 9 V battery or power supply. The higher voltage gives more dynamic range, more headroom and tighter bass – just try it!"

And  a demo video of the Diablo in action:

Here's a PDF of the OKKO Diablo schematic file: http://www.box.com/s/qz7r3bgncl3jzgugoe3e

As you can see if you look at the PDF schematic it compares very similarly to this, an old design by Jack Orman:

There's no doubt the Microbooster formula sounds great - there are so many pedals now using them in a cascaded structure - The Catalinbread Dirty Little Secret and Formula No 5, the OKKO Dominator and so on.

Harald Sabro (www.Sabrotone.com) has produced some brilliant verified vero layouts and posted them up on the freestompboxes forums:

Now, those veros don't include the voltage doubler that the original Diablo contains, so if you need to build one of these: 

Then all you need to add is a simple switch which will allow you to go between +9v and ~+18v...

Here's a link to the freestompboxes.org forum topic for reference: http://freestompboxes.org/viewtopic.php?f=7&t=1482