Keeley Mag Echo

Here's Keeley's PT2399-based delay that aims to emulate old tape delays. I think it's the first delay on the blog with built in modulation. It's laid out with board mounted pots for a 125B enclosure with top mounted jacks. FYI, the trimmer controls the gain of the input stage.

Keeley El Rey Dorado

Here's another Plexi-in-a-box overdrive, this time from the great Robert Keeley. It's a cascaded opamp design running on a bipolar +/-9v supply. The Power Toggle as it's known on the original selects between red LEDs or BAT46s for asymmetrical clipping.

Keeley 1962

Take a Blues Breaker and mash it between two Katana boosts and you have the 1962. Couple minor differences from a typical Blues Breaker beyond that. Trace over on FSB. There are two versions of this circuit, the 1962 and the 1962x. As far as I can tell, the only difference between the two is the clipping. I've added a DPDT toggle to switch between the two versions.

There's also a fabricated version in the store, the LXII.

A couple notes:

When I verified the fab'd version I didn't notice much difference tonally between the two clipping settings, so you may want to either leave it out or experiment with that section. I changed the value of the resistor from 9v to the drain of Q3 from 47k in the trace to 22k. Wouldn't bias properly otherwise. Also for the caps with questions marks in the layout above I used 10nF, except for the yellow cap to the right of the IC, which I used 100pF.

Keeley Rotten Apple

Happy Fuzz Friday, everyone! Here's another one of Robert Keeley's takes on the IC Big Muff with a quad opamp (the other being the Psi Fuzz). Pots are board mounted and it should fit into a 1590B.

Boss DS-1 with Keeley Ultra Mods

Got a request for the classic DS-1 with some Keeley mods and since my earlier DS-1 layout doesn't have board mounted pots, it seemed like a good idea. The flip-flop switching has been removed. Here's the schematic for reference.

Keeley Psi Fuzz

Happy Fuzz Friday, everybody. The Psi Fuzz is an IC/germanium hybrid fuzz. It takes some inspiration from the IC Big Muff, but with Keeley's own distinct design touches. Schematic can be found here.

Keeley 4-Knob Compressor

The Keeley 4-Knob Compressor is a modified Ross Compressor and is highly regarded in the stompbox world. It's only down side is the use of the obsolete CA3080 chip. These can be hard to find and a little pricy. However if you're unable to find one, or unwilling to pay for one, use the LM13700 chip (which is 2 3080s in one) and this conversion daughter board. The schematic can be found here. If you have a hard time getting 150k pots, use a 250k pot with a 390k resistor in parallel (between lugs 1 and 3).

Keeley Katana

The Katana is a highly regarded clean boost pedal that can give a nice clean boost or push your tube amp into breakup. The circuit itself is fairly simple, but achieves extra headroom thanks to the internal voltage doubler. For this you can use a ICL7660 or MAX1044. You may want to socket the two 4.7k resistors or replace them with 10k trimpots. The drain of both transistors need to be around 9 volts. On original units, the switch is a push/pull on the pot (which is why it's mounted to the side of the enclosure), but a regular toggle can be used. If the switch wiring doesn't make sense, reference the General Layout Notes tab for switch numbering. It should be possible to fit this in a 1590A if you're not claustrophobic. Here's the schematic for reference.

Keeley Fuzz Head

Over a decade ago Robert Keeley was kind enough to share this design with the DIY community. It's a fairly unique fuzz, with a germanium treble booster at the beginning, a differential amplifier in the middle, and a basic buffer at the output (this is so it will play nice with other effects). Robert's full explanation of the circuit can be found here, however note that the schematic in that document isn't what I used. I used this later one with a tone control, and ended up laying it out with all controls externally. The PreGain control originally was a trimmer because it has a tendency to crackle when turned, but for ultimate tweak-ability I moved it externally.

The switch is a SPST on/off, by the way.