An Electronic Debacle
There is a sailboat race in San Francisco Bay called the Three Bridge Fiasco. I could have sworn it was called the Frisco Fiasco, but it’s possible that my group of scallywags only called it that to needle people from the Bay Area (who apparently dislike that nickname, even though “Frisco Fiasco” is an objectively superior regatta name, given its hard-working alliteration and the fact that it can be neatly dropped into Esquivel’s “Mucha Muchacha” without scansion).
There are people who would say that all sailboat races are fiascos, since sailboats are inherently restricted in their maneuverability, the typical starting sequence is like the ballet version of a Hieronymus Bosch painting performed by a kindergarten soccer team, and the rules sound like magical incantations edited by 40 generations of lawyers. But the Three Bridge Fiasco has one special rule in its sailing instructions:
7.1 Boats shall round YRA 16, Red Rock Island, and Yerba Buena Island, in any order and in either direction.…meaning that in addition to the usual zaniness, any of the ~300 boats could be going around the course in opposite directions at the same time.
The Fiasco pedal is a similar sort of willful catastrophe, but most of the protest flags are flown at the subatomic level.
Details
When I was working on Another Dimension, I had an odd number of op-amps in the design. That’s annoying because a lot of the most common op-amp chips in pedal building come with a pair of op-amps on them. The pedal cognoscenti told me that instead of adding a dual op-amp and wasting half of it, I should just use one of the extra op-amps on the PT2399—the chip that provides the delay for Another Dimension. I would have done it if I could have figured out how.
An op-amp usually handles signal on three pins (inverting input, non-inverting input, and output) and I have a tenuous understanding of what to do with them when I can see them all, but in a PT2399, only two pins are exposed. The other, along with some additional fixed connections, resides within the black box of the integrated circuit. I have attempted to understand the data sheet and the third-party aftermarket addenda to the data sheet (like the Electrosmash and Valve Wizard writeups) but being a hack ain’t easy. Most of this is like trying to solve algebra word problems written in Mandarin for me—even if I could do the math (which is definitely in question), I can’t get past the vocabulary. Just use the V- and Vout of the Integrator and assume that 5.6k between them and an arbitrary 2.5V on V+ and a connection to a random thing called “MOD” will be fine, keeping in mind that the train leaving Tucson may or may not be on Daylight Savings Time depending on the current Sheriff of Arizona, 我快笑死.
In order to understand this better, I had a grand idea to mostly disregard the delay aspect of a PT2399 and focus on getting the visible two-thirds of one of its op-amps to do something I can get my head around: distorting a guitar signal. I thought that once I unlocked that mystery, maybe there would be something wacky that I could do with the remaining delay parts of the chip to have some kind of fuzz/delay combo, somewhat in the style of my Anhedonia pedal. And within a few seconds of searching, I found that (like everything in the world of guitar pedals) it has already been done.
In 2010, someone named anchovie posted “Noise Ensemble – simple PT2399 abuse!” on diystompboxes.com. In 2014, Fredrik Lyxzén from Parasit posted a vero layout for it and suggested a way to make it go into feedback by literally connecting the output to the input via a large resistor. The Fiasco is that.
To the degree that I understand it (which is mostly based on help from my pedal guru) it’s fairly absurd. It’s using the op-amp between pins 15 and 16 as an open loop comparator, which I think means that the op-amp is trying to amplify the signal to infinity in the crests and negative infinity in troughs, although in practice it can only really go between 0V and 5V (or less), since I don’t have an infinite power supply on hand and it might get warm if I did. But in op-amps and gift-giving, it’s the thought that counts, and the result is that the output is as close to a square wave as that poor op-amp can possibly make it. The output also goes into the delay circuit and to the section of the PT2399 that adjusts the delay time, so the time varies with whatever signal happens to be going through it. Modulating the delay time (in anything) results in pitch shifting, and modulating it semi-randomly based on the input adds semi-random pitch-shifted chaos on top of whatever the Chaos knob can provide on its own.
I tried to mess with it. The feedback as suggested by Parasit was pretty noisy (at least on my breadboard) and I played with keeping it more “inside” the circuit rather than outside everything, including running it through the unused Integrator section of the chip or with some clipping diodes on it that would keep it from getting wildly out of hand, and even trying to implement more rational delay repeats as it is in a Pelota (e.g., my Monotonous Delay), but I think the way the comparator fuzz is done precludes that. I tried following some general PT2399 best practices (like running a cap between Pin 8 and ground), but when you’re trying to make one into a dirt pedal, worst practices may be advantageous. The biggest change I made to the circuit is that I didn’t use a PT2399 at all…Fiasco uses an HT8970, which is an even poorer man’s PT2399 substitute, featuring half the memory. I had some left over from when I was experimenting with trying to get the Slow Danse Macabre to run at sub-30ms delay times, and I certainly don’t need long delay times for this.
At least there’s a schematic for it now, since the image files associated with the original Noise Ensemble seem to have been lost to defunct image hosting services.
Vital Stats
Sound
It’s not subtle. The fuzz is absurd, but naturally gated and eerily quiet when there’s no signal. The delay (which can never be turned completely off) has a thickening effect at low settings and a broken, de-tuned, “confused sea state” sort of thing going on when cranked. The feedback switch (marked with an asterisk) is a dang mess, and is neither like a delay set to runaway nor a guitar placed in front of a loud amp—it ranges from a kind of hissy, noisy ring to a chopped-up metallic robot sound, depending on position of the Chaos knob.
The following terrible sample is broken up into two sections:
- Part one is Coronacaster > Fiasco > clean Fender Deluxe-ish amp. It starts with the pedal disengaged, then the pedal is turned on with the Chaos knob all the way down. The odd out-of-nowhere pitch bend after the first bit of nonsense is what happens when the Chaos knob is set to medium, then more nonsense, then turned up all the way. Toward the end I engaged the feedback switch a bit.
- The second part adds in the Slow Danse Macabre chorus and Monotonous Delay for a slightly more composed sound, and includes frequent use of the feedback switch amid the wanking, kind of in the style of how the sustain pedal of a piano might be used [mental note to name a future pedal “Amid the Wanking”]
