WaveFucker
This page is an addendum to my original post… WaveFucker is an experimental sound source involving a feedback loop with analog and digital elements. The three functional blocks are a high-gain fuzz, a low-fidelity pitch shifter, and a resonant filter. The blocks are arranged like this:
I initally modeled it with Reaktor and then translated it into a hardware design. You can download the Reaktor patch here. In hardware, it is a rather simple circuit that uses only six IC’s: five 4000-series CMOS logic chips and one opamp. Pure 1970’s technology, in other words. The pitch shifter is an extremely minimal implementation that I designed, with only 16 bits of RAM. The aliasing and bit-crushing effects of the pitch shifter lend magic to its results in this application. The filter is adapted from the Ibanez Tube Screamer schematic, and the fuzz circuit is my own, designed to convert audio to 1-bit digital logic information.
Here’s what the prototype looks like currently:
Breaking the link between the resonant filter and the fuzz block configures the WaveFucker to process external audio. Or, with this link in place as shown in the diagram above, the WaveFucker becomes an unusual synthesizer that generates bizarre harmonic and timbral structures, pitch sequences, etc. The results are due to emergent properties of the system and have a strange, chaotic beauty. Its an aesthetic completely opposite to the top-down design philosophy that most commercial synths are based on. Playing the WaveFucker is more like a game in which the results are history-dependent; surprising changes often take place with the most minute tweak of a knob.
The following recordings were made by plugging the WaveFucker into a Fender Princeton Chorus on the clean channel. There is no external input.
The sounds in “harmonics” jump between pitches and appear to fall on a scale of some sort. This effect takes place upon varying the loop gain between the pitch shifter and filter blocks. To get insight into what is happening, I analyzed the first few seconds of the recording using Spectrogram_16, a free spectral analysis program from visualizationsoftaware.com. Have a look at the results:
We see a constant frequency at about 850Hz and evenly distributed harmonics below it. As the feedback loop gain increases, the overall volume goes up; simultaneously, the apparent pitch decreases in incremental steps. With each lower pitch the total number of harmonics changes but they remain equally spaced, until the lowest pitch is reached. The lowest pitch appears to be a convergence of many harmonics into three dominant frequencies. Lowering the loop gain back to zero apparently reverses the sequence. The darkest lines indicate the strongest harmonics, and these are responsible for the apparent pitch of the sound.
Here are a few examples of the effect on guitar:
as a pitch shifter: wavefucker guitar demo 1
as a “pitch memory”: wavefucker guitar demo 2
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