Kalibrus

Laboratory Precision in the Reason Rack

Kalibrus (ca.boraas.Kalibrus) is a laboratory-grade acoustic noise generator, pitch-tracking sound source, and modular CV device engineered for the Reason Rack. Designed with mathematical rigor, it serves five essential roles: an industry-standards-tested mixing reference, an inline mix-bus and mastering chain insert, a calibrated acoustic sound source for professional monitoring and room diagnostics, a modular CV modulation source, and a playable, expressive sound-design instrument for physical percussion and atmospheric synth layers.

Unlike basic software noise generators that rely on short looping samples or low-entropy pseudo-random routines, Kalibrus features a pure C++17 DSP core powered by dual uncorrelated 64-bit Xoshiro256++ PRNG engines. This ensures mathematically pure spectral energy distribution across the entire audible spectrum (20 Hz – 20 kHz) with zero audible periodicity or repeating artifacts.

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Noise Spectra

Pink Noise (-3 dB / octave)

Synthesized using an optimized 6-pole (+1 FIR) Paul Kellet IIR filter topology. Maintains tight ±0.3 dB spectral linearity across the full 20 Hz – 20 kHz acoustic spectrum. Calibrated to a bit-exact -18.00 dBFS True RMS reference at unity gain for instantaneous K-System monitor alignment and frequency-masking mix balancing.

White Noise (Flat Power Density)

Uniform floating-point mapping with equal power across all frequency bands. Essential for testing microphone responses, converter frequency linearity, comb-filtering diagnostics, and synthesizing snappy percussion transients.

Brown Noise (-6 dB / octave)

Synthesized via a first-order leaky integrator IIR filter with integrated high-pass DC bias blocking. Delivers deep, organic low-frequency acoustic energy ideal for subwoofer tuning, room boundary resonance testing, and beefing up 808 sub-bass lines.

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Transport Synchronization & Audio Insert Workflow

Kalibrus integrates directly into live mixing and mastering workflows without requiring external auxiliary mixers or routing workarounds:

• Transport Synchronization: The front-panel illuminated cyan AUTO push button locks noise generation directly to Reason’s transport state. Kalibrus emits noise automatically during playback and silences cleanly upon stopping via smooth 50 ms Hann raised-cosine enveloping. The primary ENGAGE button serves as an independent manual override latch for continuous room tuning and background pink noise mix balancing.
• Stereo L/R Audio Passthrough & Linear Summing: Rear stereo inputs allow Kalibrus to be inserted directly between a mix bus or mastering chain and the hardware output device, which is especially indispensable in Reason Free where an auxiliary line mixer is not provided. When Kalibrus is idle or silent, incoming audio passes through with bit-identical fidelity at ~0% CPU overhead. When noise is emitted, incoming audio is cleanly summed (Audio In + Noise) at unity gain.
• Combined True RMS Output Metering: The front-panel 24-segment true-power RMS LED ladder monitors the actual combined signal exiting the device, providing immediate visual verification of mix levels, headroom, and reference noise calibration.

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Compact 1U Folded Strip Workflow

When rack real estate in complex Reason projects is at a premium, Kalibrus collapses into an efficient 1U rack strip while retaining immediate hands-on control over all core functions:

• Quick Engage & Mute: Direct access to the illuminated manual Engage push button to toggle noise generation on and off without expanding the rack.
• Instant Noise Color Switching: 3-position selector (PNK, WHT, BRN) for rapid switching between Pink reference, White broadband, and Brown low-end acoustic spectra.
• Master Level Trimmer & RMS Ladder: Dedicated output attenuation knob accompanied by the 24-segment true RMS LED ladder for continuous level and headroom monitoring at a glance.
• Console Tape Preset Display: Textured artist console tape displaying the currently active preset and custom channel label.

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Synthesis & Keyboard Tracking

Kalibrus breaks the boundary between measurement tool and synthesizer:

• 1V/Oct Keyboard Pitch Tracking: Connect MIDI keyboards or sequencer gates to pitch-track Kalibrus’s filter passband center across the musical scale. Features last-note priority with pitch bend support for pitched noise percussion, tuned sub-bass tones, and wind-like melodies.
• Dynamic Velocity Sensitivity: Triggered notes respond dynamically to MIDI velocity, shaping transient burst attacks for snare layers, clap synthesis, and rhythmic accents.
• Mod Wheel Bandwidth Control: Mod Wheel (CC1) and rear Mod CV smoothly narrow the cascaded Butterworth filter bandwidth around the tracked pitch down to a 1-semitone passband, providing real-time dynamic tone shaping from wideband noise to focused pitched noise and wind-like acoustic formants (without resonant filter peaking).

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Rear-Panel Modular CV Matrix

Designed to integrate deeply into the Reason Rack’s modular cabling environment, Kalibrus provides a complete rear-panel CV patchbay:

• Pitch CV In & Gate CV In: Full 1V/Oct modular note pitch and gate triggering.
• Gate Thru CV Out: Mirrors incoming gate pulses directly to downstream synths, drum modules, or envelopes for modular daisy-chaining.
• HPF & LPF Cutoff CV Inputs: Independent bipolar CV inputs for sweeping high-pass and low-pass filter boundaries via external LFOs or envelopes.
• Output Level CV In: Voltage-controlled gain modulation with dedicated rear attenuator trim pot.
• Continuous Noise CV Out: Pure uncorrelated analog random control voltage for modulating external filters, pan positions, and oscillator pitch.
• Gate-Clocked Sample & Hold (S&H) Stepped CV Out: Produces stepped, held voltages randomized on each new external gate input, ideal for generative modular melodies and rhythms.

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Curated Factory Preset Library (22 Presets / 5 Categories)

Kalibrus ships with 22 carefully crafted factory presets organized across 5 functional subdirectories:

1. 01 Reference & Calibration (8 Presets): Bob Katz K-System RMS monitoring references (K-20, K-14, Pink Stereo -12dB, True RMS Pink Reference -18dBFS), phase coherence checks, and dual-mono decorrelated room probe references.
2. 02 Mixing & Diagnostics (6 Presets): Surgical frequency-masking diagnostic tools including Pink Noise Mix Balancing, Mud-Zone Diagnostic (200 Hz – 500 Hz), Sub-Kick Masking Probe (40 Hz – 100 Hz), Sibilance Window (4 kHz – 8 kHz), and High-End Air Reference.
3. 03 Acoustic Probes (3 Presets): Low-frequency room mode diagnostic tools for Subwoofer Tuning (20 Hz – 120 Hz), Crossover Alignment, and Fletcher-Munson human ear fatigue analysis.
4. 04 Textures & Modulation (2 Presets): Analog tape hiss noise beds and modular clock randomizers.
5. 05 Performance & Layering (3 Presets): Key-triggered snare/clap burst layers, sub-bass air weight for electronic kicks, and acoustic instrument breath chiff.