I’m excited to introduce our latest pedal, Prismatic Wall. It’s a resonator that uses your guitar/synth/other signal to excite vibrations of imaginary sympathetic strings. The end result is kind of like a reverb, kind of like a synthesizer, but also neither. This is our deepest, weirdest device yet. It makes sense when you hear it, but it’s also full of surprises. Genuinely, it’s an effect that has surprised me every time I hear someone new playing it for the first time.
If you want to learn more, check out the product page for specs/manuals/etc. We also produced a two part video manual which you can find below.
If that’s not enough, there are also approximately one million amazing demos flying around the internet right now.
Quick housekeeping : Prismatic Wall is available now through our site and participating retailers. Also, it should go without saying but this is not a limited edition product. We also didn’t use any overly weird parts. If stock runs out, we will open up an additional round of preorder slots which we expect to ship by July 31.
The Backstory
In 2012 some friends and I made a record with my now good friend Mike Moschetto at the now-defunct Office Recording (RIP) in North Andover, MA. It was my first time in a real recording studio and I look back on the whole experience fondly, but one studio technique stuck with me ever since.
To add some color to the mix (or in retrospect, perhaps to liven up the process of recording mediocre post-hardcore tunes), Mike opened up a grand piano in the live room, aimed a microphone inside, and weighed down the sustain pedal with a cinder block. Loud sounds induced vibrations in the strings, producing a lingering, chromatic reverberation. I think that moment briefly ruined conventional reverb for me. I was enamored and spent years chasing a way to replicate that sound. I’d occasionally get close using plugins, eurorack modules, and impulse responses. But none of them felt quite right with a guitar.
Some time around 2018, I observed that a resonant string sound could be approximated using a short delay with high feedback. I realized I had stumbled upon Karplus-Strong synthesis: a technique where a tuned delay line emulates the physics of a vibrating string. From there, I discovered the world that is physical modeling synthesis, and in 2019 (while still in school) I built a rudimentary sympathetic string bank in Pure Data. It wasn’t until summer 2022 that I could get it working on hardware in the form of a hacked-up Spin FV-1 dev board. Once Sending V2 was complete, I set to work pairing this concept with our new digital control ecosystem, developing a streamlined, more compact motherboard in the process. (This motherboard is definitely going in some other stuff, by the way.)
From there we spent many months building out features and fine-tuning the sound quality. More on that below. After all our hard work, I am really thrilled with the end result.
Some Technical Lore
The majority of development time was spent optimizing the sound quality. My ideal sound quality was somewhere between a polished modern DSP and the rough digital edges of the FV-1. To achieve this we implemented analog gain, filtering, feedback, and noise reduction techniques—treating the DSP almost like a weird BBD, even down to its primary method of control being a sample clock. The DSP code on Prismatic Wall operates at the absolute limit of the chip’s instructions. The resulting sound quality feels organic and not overly pristine, in a way that feels unmoored from time.
While we were focused on the initial goal of creating that piano-verb sound, we realized we could switch between multiple tuning modes. Choosing these modes was a process of discovery. There exists a fundamental tradeoff between the complexity of the physical string model and the number of elements in the digital string bank. For most of the modes, we utilized a model that could fit 5 strings with good fidelity, clear overtones, and pleasant clipping. (The chromatic mode became a way to embrace the lo-fi string model.) Interestingly, this introduced a music theory challenge. The original chromatic concept was deliberately versatile, because any notes would likely excite one of the strings. Thus, we weren’t forcing the pedal into a specific musical mode. How could we maintain that with fewer than 12 pitches? Single comb mode was an exception, as a single pitch is useful in its own way, and we could use the extra strings for an overtone series. I pretty quickly fell in love with stacked fifths as an option. It’s rich and expansive due to covering multiple octaves. The last mode was the trickiest, and I was stuck until our friend (& gifted composer/cellist/death metal vocalist) Eden Rayz suggested we try out stacked neutral thirds. By deliberately not choosing between major and minor, there is a dreamy, detuned sound quality to this mode which really tied the whole thing together. I was sold, and we had four interesting modes. Technically there’s eight modes if you factor in the octave up shift!
Prototype purgatory, featuring a “dummy” motherboard to test out some analog stuff.
A fairly hacked-up FV-1 dev board. Not pictured: lots of other massaging to keep the noise floor down.
One of the final round of prototypes.
We also got to explore some exciting new avenues of digital control. Sending V2 gave us a toolbox for digitally controlled analog, and we were able to extend that in a variety of ways. The most exciting to me is the Morphing functionality. This is built on how we do expression control in Sending V2. Essentially, you can fluidly transition between two knob settings on the fly, with intelligent momentary/latching action and adjustable rise/fall times. You can do controllable pitch jumps, feedback swells, mod wheel style LFO control, and more. It’s fun, easy to use, and great for a live performance. Another exciting one is our Mod Matrix, where the LFO can be assigned to multiple parameters on the front panel! There are many more functions to talk about if you check out the manual. Like I said above, this thing is deep.
Closing Thoughts
Releasing this pedal is a significant milestone for us. It’s not a drive pedal, and it’s not a revamp of one of my older designs. I think so often about the relationship between new sound design tools and the sense of wonder that inspires new music. I’m always chasing that feeling in some way and I think this is the closest we have gotten. So, I hope you all enjoy this. We’re all eternally grateful for being able to do this for a living.
Cheers,
John & Co