F_MECHZ

MECHZ – Mechanical Network Instrument

Overview
MECHZ is not a traditional oscillator or filter. It is a real-time mechanical simulation in which sound emerges from interacting masses and springs. Nodes represent masses, connections represent springs, and injected energy sets the system in motion. The audio output is the direct result of this motion. There are no fixed oscillators, no stored resonant modes, and no predefined spectra. Tone is the consequence of structure, material behavior, and how energy flows through the network.

Because MECHZ is physically modeled, pitch and timbre are inherently connected. Changing Mass, Stiffness, Rest scaling, Leak, or Topology will influence the perceived pitch. This behavior is not instability; it reflects the natural response of a coupled mechanical system.

Mechanical Network vs Modal Synthesis
MECHZ may resemble a modal resonator instrument, but it does not use a predefined bank of tuned resonant filters. Modal synthesizers generate sound through a fixed set of calculated resonant modes. MECHZ instead produces resonance through a dynamically coupled mass–spring system. Its modes are not stored or selected; they emerge from physical interaction between masses and springs. When structural parameters change, the system’s resonances can reorganize themselves. This makes MECHZ more organic and responsive than a fixed modal design.

Inputs
PITCH (1V/Oct) scales global stiffness so the system can follow pitch. In a mechanical model, frequency is proportional to the square root of stiffness, so MECHZ internally compensates to approximate musical pitch tracking. Because the system remains physical, tracking is still influenced by Mass, Rest, and Topology.
For accurate tracking with standard modular sequencers, set PAMT around 2.0. Lower values intentionally allow more physical drift between pitch and structure.
GATE injects energy into the system. On a rising edge, a directional impulse excites the network and initiates vibration.
RND (Random Topology Trigger) rebuilds the spring network structure on a rising edge. A short internal micro-mute prevents clicks while the structure changes.
FORCE applies a continuous bipolar force to the system. This can create sustained excitation, slow structural motion, or external modulation.
STIFF CV modulates spring stiffness in real time.
DAMP CV modulates internal damping.

Performance Controls
TUNE offsets pitch in octaves.
PAMT (Pitch Amount) scales how strongly the PITCH input influences stiffness. Higher values produce tighter pitch tracking. Lower values allow the physical structure to dominate the pitch behavior.
INJECT controls the strength of impact when a Gate is received. Higher settings create stronger impulses and more energetic excitation. Internal soft limiting and short post-impact damping prevent unstable energy spikes while preserving the attack character.
DRIVE adds continuous self-sustaining energy to the moving system. DRIVE does not inject random noise; it amplifies existing motion. At moderate levels it behaves like bowing, friction, or environmental vibration. At higher levels it can maintain continuous mechanical oscillation.
GAIN sets the final output level.

Structure and Material
TOPO selects the structural arrangement of nodes and springs. Different topologies produce very different resonance patterns.
STIFF controls spring stiffness. Higher values increase brightness and raise pitch.
MASS controls the mass of each node. Increasing mass lowers pitch and slows system movement.
REST scales the rest length of springs. This changes the equilibrium tension and shifts the resonance structure.
DAMP controls internal friction within the system. Higher damping shortens decay and reduces brightness.
LEAK controls energy loss toward the outer boundaries of the system. Unlike DAMP, which affects motion everywhere, LEAK gradually absorbs energy near the edges and gently recenters the network. Higher Leak values shorten decay and stabilize sustained motion.

Listening Section
PUP (Pickup Mode) selects how the system is “observed”. Different pickup models emphasize different aspects of the motion:
Bell mode emphasizes relative spring motion and produces metallic resonant structures.
String mode focuses on local node movement and behaves more like a vibrating string with a movable pickup point.
Drum mode emphasizes global membrane-like displacement across the network.
LISTEN selects the node used for focused pickup and stereo panning. Moving LISTEN effectively changes the “pickup position” on the virtual structure, which alters both tonal emphasis and stereo placement.

Canvas Display
The central display visualizes the mechanical network. Dots represent masses and lines represent springs. Brightness indicates kinetic activity within the system. Warmer colors reflect stronger motion or tension, while cooler tones represent lower energy states. The highlighted ring marks the current listening node.

Outputs
L and R provide stereo audio output.
ENERGY outputs a 0–5V signal proportional to the total kinetic energy of the system. This can be used to modulate other modules based on how active the network is.

Behavior Notes
MECHZ is a non-linear coupled system. Structural changes can alter resonance patterns, decay times, and perceived pitch. For stable melodic playing, keep Mass, Rest, and Topology relatively consistent and use higher Pitch Amount values. For evolving sound design, modulate Topology, Leak, Drive, and Force.

MECHZ can function both as a playable instrument and as an evolving mechanical sound source. With controlled excitation and moderate damping it behaves like a struck or bowed object. With strong Drive, low damping, and topology changes it becomes a dynamic mechanical environment.

Concept
MECHZ is not a resonator bank disguised as physics. It is a physical simulation that produces sound as a consequence of structure and energy flow. Instead of programming oscillators, you are shaping a mechanical system. The sound you hear is the behavior of that system in motion.