HungryFuzz HEY GUYS, new module!

NEW MODULE TIME! Well, prototype time. The design is done, and there's some germanium transistors that will be going in there, and they need testing. So here's the rundown of the module and circuit, and if you're looking for build tips, those are after the break!

I like distorted kicks. It's part of my identity. Both modules in my Hungry- series work so well with kicks, the HungryRat (Proco Rat clone) is HARSH SHARP, and my HungryThumb is a compressor and does amazing things to kick drums, including soft clipping, compressing, saturation, lots of fun. Well, I don't know how many germanium transistor distortion pedals have been ported to Eurorack, but the number is probably low (germanium transistors aren't common) so here we go!

The original Fuzz Face pedal "remains an enigma". It was released in 1966, consists of a battery, four resistors, three capacitors, two germanium transistors, and two potentiometers. Ludicrously simple!  The page I just linked to talks about how some of the unique sound may have been a happy accident. There's asymmetrical clipping which starts out soft and goes harder with increased signal voltage. I think that's probably the main accident?

The design has been developed exhaustively over the years, with different designers experimenting with different transistors and transistor types (NPN silicon transistors, for instance), and tweaking resistor values, and (my favorite) hurling potentiometers in there wherever they might make a difference in the sound.

For pedals, where the knobs are in the stompbox which is usually on the floor, two knobs may be fine. But we synthesizer guys love to have all the knobs at our fingertips, and the Zvex Fuzz Factory seems to be the most complex design out there, with five whole knobs to play with. So I cribbed from that circuit, added my starve circuit which also allows the distortion core to work with bipolar voltages (so there's no DC swing when adjusting the starve, right?) (although I left the DC blocking capacitors in the signal patch) (which are MLCC in the prototype because I don't believe that most capacitors "sound" like anything). There's a stupidly wonderful tone control in there, and of course a proper output buffer with adjustable gain to get the output to be a nice safe 1K impedance at 10V peak to peak.

And that's the circut! I have zero zero zero hands-on experience with a Fuzz Face of any variety, so I'm.... excited to see how the prototype sounds?

But I'm neglecting to talk about germanium transistors! They're nifty! And very obsolete. So check after the break for what to do with these weird parts!

I went microViral?

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 Okay um, I hope that worked...

I got to play a short set with my mostly-working tin can synth a couple days ago! This video was taken the night before, and as of this post, has 6.8K likes. Wow! I shall keep my head only as overlarge as it already is (I have a healthy ego) and only halfheartedly attempt to chase further likes and views. Y'know, by replying to Instagram DMs and answering questions in the comments.

Playing my tin can synth (Hello Kitty Furiosa is her name) was a TON of fun, and prompted two ideas for modules. One of my tin cans has eight knobs, three switches, a NINTH knob, a clock input and a CV output. I think the three switches are a binary number select bank (eight options) and the ninth knob is a "sequence length" selector. Mode 0B000 (all switches off) is probably a sequence of CVs that go from knob 1 to knob 8 (or less far, depending on the ninth knob). Mode 0B001 is probably "cylon" or "KITT from Nightrider flashy lights mode" that go back and forth. Modes 0B010 through 0B111 are utter mysteries to me, and are probably melody or bass lines from popular songs like Billy Jean or Part Time Lover. The theory being, if you happen to tune the CV knobs correctly, your VCO will play the desired tune, which is the strategy I used for my main CV sequencer (12 knobs actually 24 thumb-wheels with coarse and fine tune per CV step) and I have never once managed to get anything resembling Stayin' Alive (etc) out of them. BUT! The patterns remain compelling when the CVs are tuned to other notes, harmonious or un.

My second idea is a "YOI" module, which is inspired by my tin can synth lacking a sample rate reducer AKA fast sample/hold. Those sweet and mysterious YOI sounds that litter dubstep/DnB tracks like empty alcohol containers litter the floor of a dubstep/DnB venue floor can be gotten with a simple VCF (don't be shy with the resonance) and a sample/hold module. The interaction of the VCF cutoff frequency and the frequency of the S/H makes a YOI and I love it so much and don't really understand how those two things make that sound. My NyquistNightmare can sorta do YOI sounds, but a dedicated YOI module would be neat :D

Okay, that's all. I also had a cold the past few days, so my viral post went unnoticed for many many hours while I slept or read or otherwise ignored the internet. And ignoring the internet is always a good call.

DuckMixer NEW VERSION!

 I ran out of DuckMixer front panels! I'm not sure how -- did I order fewer panels than PCBs? Maybe? But because of that, I embarked on ordering more of each!

Adding new features and tweaking footprints is a great thing to do when sending out for new PCBs, and the DuckMixer had holes for the jack LEDs that were just a bit too large for the 1206 LEDs, allowing them to slip through a bit. One of the jacks was flipped 180 degrees from where it was supposed to sit, making it press up against a potentiometer.

So I messed with all that.

A couple errors!

 

Twice this month, customers have said "hey, there's something wrong with one of your modules," and both times, they've been right! Argh!

The first one was the Etch, which is the subject of the video embedded above, but who has time for five minute videos, so here's the too long; didn't watch summary: one of the jacks was upside down because I can't possibly stick with one jack footprint (especially the ones on the Etch -- the new fixed PCB has **another** different jack footprint, one that's not so dangerous) so at some point I swapped all the footprints, with different schematic symbols, which sometimes get inserted upside down or rotated in some other way. I didn't notice for the filter CV input, thus the tip and ring were swapped on the board. I should have caught it while designing -- the ring of the jack is always grounded after all, and never goes off to do something more important.

Thank you, random customer, for catching that error! The fix was easy enough -- my jack PCB footprint is as compact as I can make it, so turning the jack 180 degrees to use the other pads worked just fine.

The second module problem surfaced with the DumpsterDelay. Turns out they work fine, as built, for about half an hour, but then the signal going through the delay chip fades away to very quiet or nothing. Sounds like a capacitor loading up, doesn't it? Turns out that's exactly what it was -- there's two multiple-feedback notch filters built into the module, which don't actually get used for anything -- physically damping the Piezo elements works better than customizing a filter with weird-value resistors. BUT!!! If you look at the schematic in that link, you'll notice capacitors C1 and C2 go nowhere (kinda) if there aren't any resistors installed!! Oh noes!!!

In imaginary physics/electronics land, that's okay, but real world op amps leak a small amount of current out of their inputs. Without the resistors keeping the inputs referenced to some reasonable voltage potential (like, say, ground? or the output of the amp for proper feedback??) the current leakage out of the inverting op amp input would charge the capacitor, so the output of the amp would creeeeeep up (or down? didn't measure) until it got close to one of the power rail. This MFB filter is actually a bandpass filter, so needed to be mixed in to the original signal but inverted, turning it into a notch filter (ugh sorry for the technical blabbbeeerrrrr) so the "notch" getting mixed in was actually just a steady voltage, which pushed the signal off into the voltage region the amp could no longer reproduce.

Maybe that made sense to one reader, thanks for sticking with me.

Thank you, other random customer, for finding that error! The fix is even simpler than the upside-down jack, one need simply put a resistor of literally any common value from zero to probably 4.7Megohms in the R3 positions of the pair of filters, making the output sit at zero volts, which gets mixed in to the signal perfectly fine, like if you're making a recipe and one of the ingredients is "zero cups of cardamom" awesome, not gonna mess up a recipe with that :D

I played with the delay a bunch to make sure it works well (it does) and came away with some conclusions. First: the dumpster part of the DumpsterDelay is the Piezo elements, stuck together, which transmit the delayed signal through themselves. I'm not sure they do much besides just add some unpleasant high-frequency noise. For low values of "repeats" this is okay, it's a bit like extra-high tape hiss, but it reinforces itself with runaway repeats until the signal is just "screeeeeeee" and nobody likes a steady screeeeeeee except maybe harsh noise artists.

I bypassed the Piezos on one of the delays and it's kind of much much nicer to use..... . .. .... .. .so I guess that option exists for people who want to mod their DumpsterDelay modules.

The other insight I had is that the input attenuator knob isn't needed at all. I wonder if I felt that it was necessary because the delays signal kept getting quieter so I thought the signal going to the delay chip needed adjusting TURNS OUT IT DOESN'T

Okay that's all, thanks for reading something not written by AI. Writing like this takes effort and time of a conscious being, not just trillions of processor cycles from an unthinking probability engine. I hate getting tricked into spending time reading stuff nobody spent any time to write.

Zen Den

The Zen Den. With a camera looking at you the whole time.

Heyyy. It has been MONTHS since I worked on a synth design, or built a module, or even soldered anything at all. I miss it so much.

This picture here is how Juanito's Secret Ex-Workshop looks now. After the jump, you'll see what it looked like when it was Juanito's Secret Workshop.

Introducing: HorseDebt

 Here's a FLYING POT!!!

In my tin can synth, many of my modules need a knob AND a button, so back when I was still building tin can modules, I'd often build up a structure with my 3D printing pen (writing pen?) and get a little pushbutton underneath a pot. I even have one module with two pushbuttons under a hinged pot so push the knob up or down? That controls two parameters on one of my modules.

THREE NEW MODULES!!!!

Three? Really? Yes!!!!

Okay first off, my modules are being sold now by my very good friend Mike (Killer Bee Relay Team) over at Hive Mind Synthesis. His whole outfit is so much better qualified to handle the sales and customer service side of this than me, and I'm SO THANKFUL and happy with how it's turning out.

Next? The three modules! These aren't retail-ready, but they've been kicking around in my brain for a long time, so I'm happy to have prototypes being made right now by JLCPCB (not a sponsor). Read about the three modules after the break.