Klon Buffer

Who doesn't love a Klon, right? Here's the buffer stage of the Centaur. The original Klon uses one side of a TL072 for the buffer and the other for gain stage. If you're building the just the buffer, you can get away with a TL071. I've laid out a perf and PCB for each.

Klon Centaur - Bare Bones

This layout is the legendary Klon Centaur, but without the charge pump. The charge pump is present in the original to keep the 2nd opamp from clipping. But since there are diodes before signal even reaches that IC, it may not matter. Check out this thread on FSB for more info and schematic. Without the charge pump, the circuit was much easier to layout for a smaller footprint. Still a fairly large board, but should still fit in a 1590B.

Klon Centaur - True Bypass

Here's the Klon again. I wanted one with board mounted pots and for a smaller enclosure. You might be able to fit this in a 1590B with low profile jacks, but it will easily fit in a 125B. It's designed for 9mm PCB mount pots, though it might be difficult to find the dual-gang Gain pot. Look for Alpha part number RD902F-40-00. I've removed a few components that were apart of the stock bypass switching for the sake of space, so you'll want to use your true bypass method of choice with this one.

Klon Centaur

Don't want to spend two grand on an original? Yeah, me neither. Regarded as one of the best overdrives of all time, the Klon Centaur seems to be something that every guitarist wants on their board. This one's not going to fit in a 1590B (if you want that, check out Madbean's Kingslayer), but you might have enough room in a 125B if you turn the board sideways. This layout follows the original Centaur with buffered bypass (using a DPDT footswitch). If you want to wire it for true bypass, ignore the footswitch wiring pads, and eliminate the 4.7µ cap, 560Ω and 100k resistors on the lower right side of the board near the input. Schematic and more info can be found here.

UPDATE:

For those confused by the footswitch wiring for non-true bypass, here's a wiring diagram for reference.

Dual Klon Buffer

In an effort to make my own personal pedal board better, I'm building buffers at the input and output of my signal chain. As space and DC jacks are always a premium, I thought to build a dual buffer in a 1590A enclosure. The Klon Buffer is great and since it only uses half of a TL072, I figured I could just use the other half for the second buffer. It's a little tight depending on the jacks you use, but the board is small enough to mount vertically to an inside wall of a 1590A while the wall opposite can mount the 4 input/output jacks. Here's my drilling template to better illustrate.

And here are a few pics of my build.

Emerson Customs EM-Drive

Here's a really simple "transparent overdrive" circuit that was a must have a couple years ago. People compared it to the Klon and Timmy drives. Originals use paper in oil caps, which some claim sound better than modern film or ceramic caps. That's a debate for another time though. I've drawn it up so you can use big mojo caps, or with more common caps for a much smaller footprint. Both versions have a couple tweaks. In the mojo layout, I've added a pull down resistor after the gain pot to try and eliminate footswitch pop. In the smaller layout, I've added some optional clipping diodes (which I think really improve the sound of this thing), and power filtering and polarity protection.

Cornish Buffer

Got a request for the Pete Cornish Buffer in dual form like the one I did with the Klon Buffer. So here's both a single and a dual Cornish Buffer. The original uses a 1N5401 for polarity protection, but a 4001 or similar will work too. And you can probably get away with a small value on the power filter cap (220µ).

SoulSonic FX Stage Overdrive

Here's a cool overdrive circuit designed by Martin from SoulSonic FX. It's said to be a "Klon Killer," so if you've been disappointed by that circuit, give this one a go. Signal goes through a buffer then is split between clean out put and the rest of the effect. So not a true-bypass effect, but having a buffer in your signal chain won't kill you. And the buffer on this thing is really top notch. For switching use one side of a DPDT for the effect, and the other for the LED indicator. For more info and the schematic, check out the thread on FSB.

Buffered Bypass

Prepare for a bit of rambling: I was looking through the de-goup thread for the Cornish G2 over on Freestompboxes.org and was intrigued by the buffered bypass switching that's used on that pedal. (Before people bombard me with requests for the G2, don't worry it's coming.) Original G2s have individual PCBs for the footswitch, the bypass buffer, and the effect. Surely the first 2 can be combined, right? So I drew up the Cornish buffer with a board mounted footswitch (which I will share when I post the G2 layout), but it was too big to fit in a typical 1590B with the footswitch centered in the enclosure. Then I got to thinking about replacing the buffer circuit with one that took up less space. So I drew it up with the input buffer from the Klon and it will fit very nicely in a 1590B. This uses a board-mounted DPDT footswitch (I bought a bunch from Tayda a while back) and the on/off indicator LED can be mounted to the board as well.

I verified this over the weekend and here's a few pics of my build.

Power Brick

Here's a little utility board that could come in handy. It uses a MAX1044 or ICL7660 to convert +9v to both +18v and -9v. It's essentially the charge pump from the Klon Centaur. I've added a 10v zenner (1N4740) diode to protect the IC, but that's optional.