Brigade

Brigade is Greybound's first delay model. The reference target is the compact analog BBD delay family typified by the Boss DM-2: short-to-medium delay times, dark repeats, softened attack on each repeat, bounded feedback, and a wet/dry mix that sits behind the dry guitar.

The implementation does not copy a factory schematic. It is a graybox model that captures the useful engineering behavior: buffered high input impedance, input coupling, long fractional delay storage, BBD-like bandwidth limits before and after the delay, saturating feedback, dark repeat filtering, wet/dry mix, and low output impedance.

Reference Placement

The reference rig places Brigade in the amp fx_loop:

• amp preamp send drives the delay input,
• repeat tails follow preamp gain rather than being repeatedly distorted by the preamp,
• low output source impedance returns into the amp FX return.

It can still be placed before the amp input for older pedalboard-style echo into amp drive.

Controls

• time_ms: delay time in milliseconds.
• repeats: feedback amount around the delay path.
• tone: repeat brightness.
• mix: wet/dry blend.
• bypass: routing state; private delay and feedback state remain owned by the pedal instance.

DSP Mapping

• Input boundary uses ConnectionState with high input impedance and cable capacitance.
• Input coupling removes DC before the delay path.
• Pre-delay low-pass filtering approximates limited BBD bandwidth.
• Fractional delay stores up to the maximum supported analog-style delay time.
• Feedback is low-pass filtered and softly compressed before it re-enters the delay path.
• tone blends darker filtered repeats with a brighter compressed repeat path.
• Output is clamped and exported through a low output source impedance.

Validation

Current validation is behavioral:

• feedback creates an audible delay tail after a short input burst,
• active FX-loop output remains audible,
• rig parser accepts all Brigade controls,
• CLI runtime controls are shared atomics so the monitor can edit delay time without locking the audio callback.

Useful next checks:

• render impulse responses for several time_ms values,
• verify repeat decay time against reference settings,
• add optional modulation/noise controls after the base delay is stable.

References

• The Boss DM-2 family is the primary musical reference: compact BBD delay with dark repeats and a simple repeat-rate/intensity/level control surface.
• Public BBD delay schematics are used only as topology references. The source of truth for Greybound remains this model document plus the Rust implementation.