Tamed Random Source

sapèl / saˈpɛːl / s.m. [dialect from the northern area of Modena – Italy, uncertain etymology: probably from vulgar Latin sappa, ‘hoe’, meaning ‘roughly hoed’] – ‘mess’, ‘muddle’, ‘chaos’.




415,00  + VAT

In stock


SAPÈL is an analog generator of random control voltages for Eurorack modular systems. It generates a wide variety of random values to add dynamics to your patches. Such values are sampled on analog thermal noise to guarantee the truest random generation.

Its main section is composed of two identical clusters of four Sample and Hold circuits each (yellow and green), generating as many different random values simultaneously.

Three of the four S&H circuits in each cluster provide stepped random voltages: two are quantized (in “notes”), and one is unquantized; the last S&H circuit features an integrator to generate a fluctuating stream of random voltages.

The three stepped voltage generators are synced, which means they will output three different values simultaneously. The yellow and green generators have two independent internal clocks, which can be replaced with an external one, or temporarily overridden via an external signal or the manual button.

Regardless of the clock used, each S&H cluster features two clock outputs: one that mirrors the input clock and another that provides a random clock behavior.

On the other hand, the fluctuating voltage generator is independent and has its own potentiometer to define its rate.

Each of the two S&H clusters samples its values from analog noise, thus providing a “true” and completely unpredictable randomness.

The second section of SAPÈL features four analog noise outputs derived from the analog noise used to sample random values.

Key Features

SAPÈL has two analog sample-and-hold circuits that generate eight random voltages simultaneously from analog thermal noise.

Each circuit has its own internal clock, which you can override with external trigs.

You can trig the four random generators in four ways:

  • With the internal clock;
  • With external trigs (overriding the internal clock);
  • With external signals (without overriding the internal clock);
  • With the built-in button.

You can also modulate the internal clock’s rate externally.

Each random generator has a clock output and a Random clock output.

In Less Than mode, the Random clock outputs just some clocks here and there.

In More Than mode, it outputs more random clocks than the main one.

In both cases, the Global Rate of Change defines the random clock density.

The 2ⁿ circuit generates random voltages precisely tuned to 12-EDO semitones.

The n+1 circuit outputs random voltages quantized to octaves.

Both circuits’ knobs define the n value, from 1 to 6: in this way, the 2ⁿ section can output 2, 4, 8, 16, 32, or 64 semitones, while the n+1 circuit can output 2, 3, 4, 5, 6, or 7 octaves.

We, of course, drew from the classic Buchla 266 but redesigned the circuit from scratch to provide a more even and “musical” value distribution.

This circuit generates a smooth, fluctuating random voltage.

It is the only random output that is not linked to the clock. It is a separate S&H circuit that integrates its values.

Its knob defines the fluctuation rate, from subtle, LFO-like frequencies to a sort of audio noise.

The Fluctuating Random knob also defines the random clock probability (Global Rate of Change).

Each generator has a classic, unquantized S&H circuit. Its wide range and its all-analog generation guarantee true noise: you won’t get two similar voltages in a row for a while!

SAPÈL also has four analog noise outputs that provide Blue, White, Pink, and Red noise.

Hissing cymbals, roaring thunders, and windy seashores are at your fingertips.

This circuit allows you to control the average random voltage magnitude. From left to right, it will make the S&H circuits generate more low, mid, or high values, respectively.

On each section, you can route the Probability Distribution to each of the four random noise generators independently.




Additional information

Weight 0,366 kg
Dimensions 15,6 × 11,7 × 6 cm



18 HP


38 mm

Current draw

270 mA @ +12 V

170 mA @ -12 V

Recommended warmup time

30 min

CV input impedance

>90 KΩ

Clock input impedance

>90 KΩ (on positive pulses)

~30 KΩ (clamping negative pulses)

Built-in clock frequency (1)

~0.1–60 Hz

Quantized Random Voltages tolerance

<1 %

+/-10 mV

Clock output (period)

~2 ms

Clock output (amplitude)

~9 V

Sampling glitch

>400 ms

Blue noise output level

10 dBU RMS

White noise output level

10 dBU RMS

Pink noise output level


Red noise output level


Noise output global tolerance

+/-2 dB

(1) Lower frequencies (i.e., slower clocks) may be achieved with a negative CV used as modulation.



Our modules are packed with high-quality components that demand a proper power supply and can get sensibly warm.

That is its normal temperature and we can guarantee their performance.

Yes! We opened our online store in October 2022. Check out the full catalog!

In Europe, we sell exclusively through our distributor: we do not have access to the individual shops’ orders or stocks.

In the rest of the world, we sell directly to the shops, but even in that case, there’s no way for us to know whether the modules that we’re restocking are sold, available, or reserved for another customer.

We restock every module at least once over a year: we focus on a module’s batch at a time, then we move on to the next one, and so on.

If you want an estimated delivery time for a specific module, drop us a line! We’ll be happy to answer you.

The MOD inputs route an external signal to an array of 16 filters at the same frequencies of the main filter array that shapes the sounds you patch to the MAIN input.

However, the product of these 16 modulation filters is not audible, since their purpose is to generate as many envelopes according to the intensity of the signal passing through each band. The envelopes then control the amplitude of the main 16 bands. This function is often referred to as ‘spectral transferring.’

If you patch an LFO to the modulation inputs you will not hear anything, since its frequency will be below the cutoff of the lowest filter.

If you patch a sawtooth or a square LFO, however, FUMANA will detect the transients, thus providing interesting, snappy sounds.

You may also like…