Frap Tools SAPÈL 1/4: Demo + Overview
This first of four movies on the Frap Tools SAPÈL Tamed Random Source – a very nice evolution of the Buchla 266 Source of Uncertainty module. The idea behind it is to provide a selection of random voltages: a typical sample & hold plus two other triggered-and-held voltages with a limited number of potential outputs to provide a set of predictable voltages that nonetheless have a random occurrence. It also features a smoothly fluctuating random voltage that is unlike a periodic LFO. Since many of these functions are driven under the hood by noise, both the 266 and the SAPÈL have multiple colored noise outputs as well.

What makes the SAPÈL different is that it ties together these outputs with centralized clocking (internal or external), as well as a probability function that will weight the various outputs toward lower or higher outcomes. Whereas the sample and hold section is unquantized, the other two are internal quantized to 1.00 volt intervals (good for selecting octaves), and 1/12v intervals (good for selecting semitones, as well as words or formants in select modules such as the Synthesis Technology E950 and the LimaFlo Motomouth). And, there’s two full sets of these random functions per module, as well as a way for the clocks from each half to cross-trigger each other.

I admit that I was initially wary of the SAPÈL: Its minimal front panel markings and density of controls made me assume it would be hard or unintuitive to use. After reading through the manual, instead I found it surprisingly easy and natural to use; I created the patch that starts this movie in my first session with it.

This demo + overview movie covers a bit of ground. The first half of it is the “teaser” movie I released on August 20. I start describing the overall patch at 02:18 (Learning Modular Patreon supporters got a detailed patch breakdown in this August 9 post https://www.patreon.com/posts/frap-tools-sapel-13766759) including an overview of the new LimaFlo Motomouth formant filter starting at 03:00. I go through the major sections of the SAPÈL itself starting at 03:38, including the four colored noise outputs along its right edge, and its sample and hold (which I don’t otherwise touch on in these videos):

It’s worth noting that the noise outputs are a full +/-8v range, which is a nice change after dealing with the very quiet, line-level-ish noise outputs in the otherwise wonderful Sputnik West Coast Random Source. On the other hand, unlike a typical sample and hold, the SAPÈL does not have a separate input to sample – it uses an internal noise source instead.

The following three movies in the set cover two sections each of the SAPÈL: part 2 covers the two quantized stepped outputs; part 3 covers the smoothly fluctuating output as well as the probability distribution function that affects all of the random outputs, and part 4 covers gate outputs (complete with a gate skipper/random burst function) as well as the clocking section, including the ability for both clocks to trigger one of the sections for arrhythmic clocking. Learning Modular Patreon supporters also get access to a bonus 5th movie (to be released September 1) that shows how I patched the non-octave interval jumps you may have noticed in the original teaser demo.


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