Minotaur

Minotaur is Greybound's first overdrive pedal model. It targets the broad behavior of buffered clean-blend overdrives: high input impedance, low output impedance, gain-dependent clipping, a treble/presence control, and enough headroom to push an amp without behaving like a fuzz.

Circuit Diagram

Diagram data lives in knowledge/models/pedals/overdrive/diagrams/minotaur.diagram.json5.

This JSON5 graph is a documentation and renderer artifact. It maps the buffered input, clean/drive blend, clipping, treble, and output stages to the current Rust emulation and includes partial SPICE export fields for explicit electrical boundaries.

Circuit graph

Minotaur overdrive documentation graph

documentationrust-model

Baseline Assumptions

• Buffered input with about 1 MOhm input impedance.
• Low output impedance suitable for driving long cables or another pedal.
• Input coupling that removes DC and keeps low frequencies controlled.
• Gain path with soft symmetrical clipping.
• Clean path blended with the clipped path so low and medium gain settings preserve pick attack.
• Treble control that emphasizes presence rather than creating a deep mid scoop.

Controls

• gain: amount of clipped drive path and clean/drive blend.
• treble: presence-band lift after the clean/drive blend.
• output: final level into the next load.
• bypass: routing state; active circuit state remains private to the pedal instance.

External Boundaries

The pedal receives and emits voltage plus impedance:

• input source: guitar pickup or previous pedal output,
• input load: Minotaur input impedance plus cable capacitance memory,
• output source: pedal output voltage plus output impedance,
• output load: amp input, next pedal, or FX-loop return.

ConnectionState owns cable capacitance and source/load division. Minotaur should not mutate amp internals.

Current DSP Approximation

The first implementation is a scalar approximation:

• high-pass input coupling,
• low-passed clean path,
• soft-clipped drive path,
• gain-controlled clean/drive blend,
• treble high-pass presence path,
• output low-pass smoothing and low source impedance.

This is not yet a component-exact op-amp/diode solve. It is intentionally shaped around useful engineering boundaries first so it can participate correctly in arbitrary rig ordering.

Validation Gates

The model is not component-exact until:

• input and output impedance targets are measured against reference data,
• gain sweep changes harmonic density while preserving clean blend at low settings,
• treble sweep changes presence without excessive level jumps,
• output level into 1 MOhm, 500 kOhm, 220 kOhm, and 100 kOhm loads behaves plausibly,
• buffered-source and guitar-source inputs produce sensible differences,
• SPICE or measured captures validate individual stage responses.

Measurement Protocol

Hardware or SPICE captures should include:

• supply voltage and current draw,
• input impedance at 100 Hz, 1 kHz, 5 kHz, and 10 kHz,
• output impedance across output settings,
• bypass behavior,
• gain, treble, and output potentiometer taper,
• clean path, clipping path, tone output, and final output probes,
• sine tests at 82 Hz, 110 Hz, 220 Hz, 440 Hz, 1 kHz, 3 kHz, and 6 kHz,
• input amplitudes from 20 mV RMS to 1 V RMS, with large amplitudes only from a buffered source.