Entangled Sound Sources

brenso /ˈbreːnso/ adj. [slang portmanteau word created from the Italian adjectives breve ‘short’ and intenso ‘intense,’ probably around the early 2000s in the area of Bologna; pronounced with the long, closed e instead of the expected open ɛ, as typical of the Northern Italian regions] — This adjective may have originally referred to events or experiences that were particularly powerful despite their short duration. Soon its meaning broadened, indicating anything (objects or even thoughts) that feature great content in proportion to the size. For example, nowadays, a thick lasagna or a massive live performance can be equally ‘brense.’


38 mm deep

325mA +12V   –   235mA -12V


BRENSO is Frap Tools’ primary analog source of articulated waveforms whose degree of entanglement can be precisely set by the musician.

Its concept developed from a reflection on the very meaning of the word ‘complex,’ which comes from the Latin verb plector, literally meaning ‘to weave.’ The purpose of BRENSO is to update the usual approach to complex oscillators by offering many threads to be woven together, rather than a pre-defined weft of controls and waveforms: this to improve clarity, manageability, and to provide more sonic options to the artist.

BRENSO consists of three sections: two for the sound generation (yellow and green), and one for sound processing (white and red).

The generation sections allow control over the two triangle-core oscillators, which can be modulated and synced both internally and externally. The Frequency Modulation can be any combination of exponential and/or linear through-zero.

The processing section is composed of a Timbre Modulation section (white) and a final stage of Amplitude Modulation (red). The Timbre Modulation contains two parallel waveshapers with a PWM circuit, which are mixed with a crossfader and processed by a wavefolder. The wavefolder has symmetry control and can be pinged through a dedicated clock input with a shapeable, nonlinear behavior.

A four-quadrant multiplier further modulates the timbre-modulated sound with the green oscillator’s sine wave: it can perform amplitude modulation or ring modulation, and a crossfader defines the balance between the modulated and unmodulated signal.

The Timbre section CV inputs are semi-normalled to a Timbre Modulation Bus, which is, in turn, semi-normalled to the green sine wave. Many other modulation destinations are semi-normalled to the other oscillator’s sine wave, with attenuverters and attenuators to guarantee precise control. All the semi-normalizations can be ‘broken’ anywhere throughout the signal routing according to the musician’s needs.

Expanded modulation routing (FM, Timbre, AM, RM)

BRENSO brings to the surface all the ways of shaping your sound: frequency modulation, amplitude modulation, and timbre controls.

Both oscillators have their independent FM modulation circuit.

The yellow oscillator, then, feeds a Timbre Modulation section which, in turns, can be blended with its amplitude- or ring-modulated copy.

Original Timbre Shaping Design

We designed the timbre modulation section from scratch with two wavefolders, a waveshaper, and a PWM circuit.

A dedicated VCA controls the global amount of modulation to each parameter section. The green oscillator is the default modulator, but you can override the semi-normalization anytime.

Exponential and Linear Through-Zero FM

Many controls allow for complex and detailed FM sound shaping. It is possible to set exponential and linear thru-zero FM independently per each oscillator and control the FM Deviation through two separate knobs or CV inputs.

(The green oscillator can also work at sub-audio rate and can therefore become a super complex LFO!)

Coarse Frequency Lock

No more tuning issues during a performance!

Every oscillator has a button that locks its coarse frequency to the current value. From this moment on, every twist of the ‘Coarse’ knob will be ineffective (but The Fine knob is still available, from small adjustments on the fly!).

Analog Thru-Zero Triangle Cores

BRENSO’s oscillators feature thru-zero triangle cores, which guarantee exceptional tracking and the best response to audio-rate modulation.

You won’t need to find a sweet spot because we designed BRENSO to sound ‘as expected’ in any setting!

Eight waveform outputs

The green oscillator has four outputs: sine, triangle, square, and sawtooth.

The yellow one has four outputs: sine and triangle as well, then a selectable square/shaped square output, and a Final output for the triangle wave after its routing through the Timbre and Amplitude Modulation sections.

Original Timbre Shaping Design

We designed the timbre modulation section from scratch with two wavefolders, a waveshaper, and a PWM circuit.

A dedicated VCA controls the global amount of modulation to each parameter section. The green oscillator is the default modulator, but you can override the semi-normalization anytime.

Pingable Wavefolder

We designed from scratch an analog circuit that, when excited by an external trig, opens the wavefolder above its maximum level and then closes it down with a non-linear slope, whose length can be manually regulated.

This solution can generate percussive tones with a very organic decay.

Oscillator Syncing

You can sync the green oscillator to the yellow one in two ways.

The Lock Sync removes any unwanted beating and preserves tracking.

The Flip Sync reverts the synchronized oscillator’s direction to the rising edge. It is similar to the classic Hard Sync but without forced restarts and sudden “pops” like in sawtooth-core oscillators.


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.

We don’t sell directly. Please check our Reseller List to choose your favorite shop!

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 higher oscillator crosstalk recorded is -50dB at higher frequencies, where it can be more noticeable.

The timbre section is part of the sound generation and we designed the signal path to derive its waveforms straight from the oscillator’s core, so no, it is not meant to be used with external signals.

BRENSO uses a microcontroller to perform the digital sample-and-hold that we use for the Coarse Frequency Lock. When you push the button, the circuit will sample the frequency value and hold it until you push it again.