Frap ToolsBrenso Complex Oscillator


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Frap Tools Brenso

The Frap Tools Brenso is an analog complex oscillator that has extensive modulation possibilities and interesting takes on waveshaping. While clearly inspired by the Buchla 259, Brenso provides its own novel interpretation of the complex oscillator concept, providing a fresh set of ideas to a classic synthesis tool.

The heart of the Brenso is the two triangle-core analog oscillators, one labeled in yellow and the other in green. The oscillators can be modulated with exponential or linear thru-zero FM with adjustable depth. Thru-zero modulation causes the oscillator to flip and run backwards into negative frequencies, folding the waveform over upon itself. The green oscillator can be set to run at audio or sub-audio frequencies. The oscillators also feature a lock button which locks the large coarse tuning knob so it can't be knocked out of place, particularly useful in a live setting. With the coarse control locked, the smaller fine control knobs still affect the frequency, allowing you to dial in slight tuning adjustments if necessary.

The white section of Brenso is the timbre section, featuring four flavors of wave shaping. There are two waveshapers. The first is for the sine wave, which transforms it from a sine wave to a triangle and finally to a logarithmic waveform. The other waveshaper is a pulse wave shaper, which emphasizes different harmonics and at higher settings inverts the phase of the pulse wave. The pulse shaper section also features PWM for adjustment of the pulse width before the waveshaper. The mixer mixes between the two waveshaped outputs. The output of the mixer is fed into the wavefolder, which has symmetry and fold controls. The wavefolder also features a pluckable clock or trigger input with non-linear release that automatically increases or decreases release time based on the frequency of the input triggers. After the waveshaping section, the signal is passed to the red amplitude modulation section. The amplitude modulation can either be unbalanced amplitude modulation or balanced ring modulation, also known as four quadrant multiplication.

Brenso features four integrated modulation buses: green FM, yellow FM, amplitude modulation, and timbre modulation. The green oscillator is the primary normalled modulation source, modulating the other parameters with the sine wave output via the modulation bus. While it acts as the primary modulation source, the green oscillator is also internally modulated by the yellow oscillator—enabling complex knots of intertwined timbral changes. The waveshaping modulation bus has one global depth control, and the green oscillator is also internally normalled into four points of the waveshaping section. These internal normalizations can be overridden using any of the waveforms or with external modulation sources.

While Brenso draws inspiration from complex oscillators from the past and present, it was designed with an eye to the future and features powerful waveshaping and modulation opportunities, which together are capable of a vast array of sonic possibilities.

Brenso Features

  • Complex oscillator
  • Two triangle-core oscillators
  • Exponential and thru-zero linear FM
  • Four modulation buses
  • Pulse waveshaper with PWM
  • Sine waveshaper
  • Wavefolder with symmetry and fold control
  • Pluckable input with decay on wavefolder
  • Four oscillator outputs per channel
  • Balanced or unbalanced amplitude modulation
  • Oscillator frequency lock button
  • Eurorack module
  • Width: 30hp
  • Depth: 38mm
  • Current draw: 325mA @ +12V, 235mA @ -12V
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Product Demo Videos
Frap Tools Brenso & 1010 BitBox Micro Eurorack Modular Synthesizer Jam
In this jam we used the new Brenso oscillator from Frap Tools as the main synth voice, the 1010 Music Bitbox Micro is providing the drum samples and the sequencing is provided by the Make Noise 0-CTRL and ALM Pam’s New Workout.

The Brenso is a dual oscillator capable of frequency and amplitude modulation as well as the ability to sync the oscillators to each other. There is also a built in wave shaper that allows you to dynamically control harmonics. The wave shaper section can also be used as a VCA, this allows you to just add an envelope generator and have a complete synth voice. In this video we used the Frap Tools Falistri to generate envelopes to modulate the amplitude and FM amount. One of the patches uses a little bit of filtering from the new version of the Mutable Instruments Ripples. Using a sequencer like the 0-CTRL for this type of synth voice works well since you can control the pitch as well as other parameters. We also added some modulation with the XAOC Batumi quad LFO.

The drum sounds are all samples from the new 1010 Music Bitbox Micro which is a smaller version of the original Bitbox, even though it is smaller it still has 8 channels and is a good option to add sampling to your eurorack modular. The drums are sequenced by the Pam’s New Workout used as a clock divider.
Overview and Frequencies | BRENSO Tutorial pt. 1
The first part of our in-depth BRENSO tutorial is here! First, we'll do an overview of the complex oscillator, explaining its design and its architecture. Then, we'll dive into the first section, the Frequency one! In the next episodes, we'll explore the Timbre and Amplitude Modulation sections, and we'll expand the concepts of Thru-Zero FM.
Frap Tools Brenso Complex Oscillator Reviews