Schlappi Engineering — Angle Grinder

Schipp Engineering ANGLE GRINDER Cheat Sheet

A powerful eurorack quad oscillator / filter / waveshaper.

Mode	How To
Quad Oscillator (SPIN)	GRIND→SPIN full CCW, DAMPING full CCW, Input unpatched, set sliders/GRIND to taste
Waveshaping (GRIND)	Patch signal to IN, monitor GRIND OUT, blend with sliders/GRIND CV, try SPIN oscillating or as LFO
State Variable Filter	Patch signal to IN, turn up GRIND→SPIN (CW), DAMPING to taste, SPIN outputs become LP/BP/HP/Inv BP

Jack	Function	Voltage Range
IN	Audio/CV input to GRIND section	Typical Eurorack audio/CV levels
INJECT	Direct input to SPIN core (bypasses GRIND), header-selectable AC/DC coupling	Audio/CV, AC default, spikes for soft sync in AC mode
V/OCT	Exponential 1V/oct for SPIN pitch	0-5V (tracks 4+ octaves)
FM1	FM input for SPIN (linear/exponential selectable by rear jumper)	?
FM2	Additional exponential FM input for SPIN	?
GRIND CV 1-4	CV over GRIND VCA per stage (added to corresponding slider)	0–5V unipolar

Jack	Function	Voltage Range
GRIND OUT	Output of GRIND waveshaping/mixing section	Up to ±11V (22Vpp, not limited)
SPIN (0°, 90°, 180°, 270°)	Sine outputs/quadrature when oscillating, filter responses when filtering	±2.5V (5Vpp) for sines, up to ±11V when filtering
SPIN LP, BP, HP, Inv BP	Same four jacks, but named for filter responses when not oscillating	±11V (22Vpp, not limited)

Name	Function
SPIN	Coarse tuning (frequency)
FINE	Fine tuning (frequency)
DAMPING	Counteracts SPIN oscillation for filter mode
GRIND→SPIN	Feedback from GRIND output to SPIN section (controls filter drive / disables osc)
GRIND IN	Mix amount of internal (or external) signal to GRIND processing

Name	Function
GRIND SLIDERS (1–4)	VCAs for each comparator phase; blends corresponding SPIN output into GRIND. Summed with associated GRIND CV input (0–5V)

Name	Function	Location
RANGE	Oscillator range: LOW (0.3–600Hz) / HIGH (10Hz–20kHz+)	Panel toggle
FM1 EXP/LIN	Selects FM1 mode (jumper on module rear)	Rear header
INJECT AC/DC	Selects AC or DC coupling for INJECT input	Rear header (AC default)

SPIN outputs phase-aligned sines when oscillating, or SVF responses when acting as filter.
GRIND outputs highly variable, complex, or distorted waveforms--morphable by sliders/CV and input/CV mixing.
GRIND→SPIN CW: Strong nonlinear feedback, disables self-oscillation, module acts as a filter.
Inject jack can hard-reset oscillator for sync (AC mode for spikes).
1V/oct tracking is good for 4+ octaves at V/OCT. Ensure FM1 is zeroed if unpatched for precise tracking (FM1 is normalled to GRIND OUT).
Max output from some outputs can reach ±11V (22Vpp)--ensure downstream circuitry tolerates this.

Quad LFO: LOW range, patch four SPIN outs to CV destinations for quad panning or modulation.
Supersaw: Feed triangle into IN, GRIND OUT gives thick, animated wave.
Metallic Drones: Patch audio rate to IN, use as filter/waveshaper at high DAMPING and GRIND→SPIN.
Stereo FX: Pan/mix 0°/180° or 90°/270° outputs for spatial effects.
Soft Sync: Use INJECT (AC) with another oscillator to soft-sync Angle Grinder.