Jon Patton Cruz Drive

Here's an transistor-ization of the Butler Tube Driver by Jon Patton. Here's what he had to say about it:

I replaced the op amp buffer + inverting drive stage with a MOSFET booster, and replaced the tube stages with with FETs in the normal manner. Note that the design inverts phase, which the original did, too.

I moved the tone controls to put it before the last gain stage because otherwise it was just insanity on the gain levels. It's already pretty nuts even with all the cuts in front of each stage, but this gives a lot more control over the overall clipping.

The tone control and switch are really what make this cool... Really I'm just re-purposing once again the tone control from my Sakura amp, but everything worked out just right for me to get a third mode out of this one and to have a usable bass control.

1) The bass control just shaves off some low frequencies below about 400Hz. It's is a shelf filter, so the bass isn't gone, just de-emphasized, and at 5:00 the cutoff is at 18Hz.

2) Treble/Tone control: This is based on a version of the Big Muff tone control, with the resistor to ground for the lowpass removed. A lot can be done to radically alter the behavior of the tone control just by varying C9, so that's what the switch does. R8 is a small resistor (I picked 2.2K) to limit the ultimate range of the tone control so that it doesn't turn into a full low-pass filter, but it can be omitted for some very very dark settings in the scoop mode. I just don't like tone controls that bottom out.

Three modes:

a) Mode 1 flipped to one side: Flat treble at ~3:00 on the knob, at 5:00 a VERY tiny boost in the treble above 700Hz, and CCW cuts the treble at that same frequency, like a see-saw. With both tone controls down, it'll form a mid hump right around the middle of a Fender amp. (If I were to leave off the switch, this is what I would use as the stock mode.)

b) Mode 2 in the center: At ~3:00, the mids are boosted by about 3dB centered ~1KHz (bass and treble are flat). There's again a slight treble boost at full. CCW, the treble gets cut at 2KHz, so it's milder than mode 1, for just shaving off the harsher harmonics created by the distortion. This mode was a freebee on the layout by adding one capacitor, so I saw no reason to omit it. It's not as dramatic as the other modes, but it will usually sound flatter when there's a lot of distortion present.

c) Mode 3 (flipped the other way) has a mid scoop at ~250Hz for added clarity (this is the "mud" frequency for guitars, so it's a good frequency to cut). CCW, the treble is cut very deeply, which allows for bass boost with the bass at full and the tone turned down, or a treble boost with the tone up and the bass down. But with the treble and bass at about 9:00, it's back to a nearly flat response but with the gain cut a lot, for some "mostly clean" boost settings.

Jon used an on board LT1054 charge pump to run the circuit on +18v, but I'll leave the method/chip selection of doubling voltage up to you. The 2k and 10k trimmers are for biasing the JFETs, and the 100k trimmer is for biasing the MOSFET. Here's the schematic for reference.

Jon Patton Cardinal Tremolo V2

The Cardinal Trem is a harmonic tremolo designed by Jon Patton and meant to emulate the tremolo effect built into several Fender amps from the early 60s (Twin, Super, Pro, Showman, etc). What makes it harmonic? The audio signal is amplified by the first JFET stage, then split into a high-pass path and a low-pass path. Each path is modulated optically with the vactrols, then amplified and mixed into the output. The LFO is designed around a quad opamp (in the original it's a quad, I had to divide it into 2, dual opamps to make it fit) and pulses the LEDs in the vactrols. Schematic and full circuit explanation can be found here.

The L pad will need to be grounded in some fashion for the LEDs to pulse. LED1 can be used as an external rate indicator, either on all the time or as the on/off indicator as well. Jon recommends using optical bypass for this effect (hence doing the Optical Bypass layout on Tuesday 😁), so to use LED1 as the indicator LED, connect it to both pads for the LED on the Optical Bypass board and ground the L pad. If using a 3PDT, just connect the L pad to lug 4 and lug 5 to ground as outlined in the General Layout Notes page.

Jon Patton's Mossy Sloth

Finishing out Jon Patton week with the Mossy Sloth Fuzz for Fuzz Friday. It's a pretty unique transistor-based fuzz and uses MOSFETs to create some asymmetrical clipping for some unusual fuzz and distortion sounds. Loads more info can be found here.

Jon Patton's Blue Warbler

Continuing Jon Patton Week with a vibe/tremolo effect called the Blue Warbler. It features envelop control over the LFO and can be built with one or two LDR stages (layout below reflects the 2 stage version). Jon explains it best, so be sure to check out his build doc and demo below. It'll be a little tight in a 1590B because of the way the pots are board mounted, but should be doable.

Jon Patton's Clipper Ship

Jon has contributed a lot to the DIY pedal building community and I always learn something new when I layout one of his circuits. So I think we'll have a Jon Patton week, starting with the Clipper Ship. There's a good bit of flexibility with this one. Q1 can be pretty much any low gain transistor, germanium or silicon. If you're using a germanium transistor, use a germanium diode for D2 (if you're using a silicon transistor, omit D2). For D3-4 use anything with a low clipping threshold–1N60, 1N34, BAT41, etc. Q2-3 form a cascaded JFET stage (much like the AMZ Mini-Booster and a ton of other designs). Way more info on the circuit can be found here, including the schematic. I've laid it out for a typical 1590B with board mounted pots.

Oh, and D1 is a 1N5817 or similar for power protection. 

Jon Patton's Hamlet Delay

Here's another design from Jon Patton. It's a delay based on the popular PT2399, with an always-on preamp. The preamp is designed to have a flat EQ and won't alter your tone. So the In and Out pads go to the input/output jacks, instead of the switch. You could still wiring this for true-bypass (just jumper the footswitch pads), but it's designed to use a DPDT. Use one side to turn the delay on/off and the other for the LED indicator. Check out his build doc for a thorough and much better explanation of the circuit, a diagram for the footswitch wiring, as well as the schematic. In his layouts he has the Level and Tone controls as trimmers on the board. I chose to move these off-board, as it seems like useful controls to have externally.

Jon Patton's Snow Day Overdrive

Here's a cool design by Jon Patton (seriously though, everything he designs is pretty awesome). He was kind enough to share his work and offer a full circuit explanation over on DIYSB and Madbean's forum too. Check out the thread here or here for his schematic and other goodies.

Bearhug FET Compressor

Here's a simple compressor design by Jon Patton (aka midwayfair) that's good for guitar and bass. In Jon's words:

The Bearhug is a tonally transparent, ultra-quiet, tiny, and easy-to-build compressor. It occupies some middle ground between the ultra-subtle compressors like the Flatline/Afterlife and Orange Squeezer and the super squishy compressors like the Ross.

For more info on the design, Jon goes into detail in this thread on DIYSB.

I built this one last night and it's everything Jon says it is. Very subtle, and a little bit of volume boost if you want it. Here's a few pics of my build.