Schlappi Engineering Angle Grinder

Name: Angle Grinder
Brand: Schlappi Engineering

Quadrature sine oscillator, state-variable filter and feedback waveshaper

18 HP Eurorack module

Angle Grinder is an all-analog, OTA-based module with two interacting sections. SPIN is a quadrature sine-wave oscillator producing four phase-related outputs (0, 90, 180, 270 degrees). GRIND is a network of four comparators, four VCAs and a mixer that compares each SPIN phase against an input signal and subtracts the result, generating complex waveshapes. When GRIND is fed back into SPIN (via the GRIND -> SPIN knob) the four outputs transform into a state-variable filter (low-pass, band-pass, high-pass, inverted band-pass) and the GRIND sliders become voltage-controlled nonlinear feedback paths for harsh, unpredictable timbres. Whether it behaves as an oscillator, filter or distortion effect depends on the knob positions and the presence of an input signal.

Features

All-analog OTA-based quadrature sine oscillator
Four phase-related outputs: 0, 90, 180, 270 degrees
Doubles as a state-variable filter (LP/BP/HP/Inv-BP)
GRIND section: four comparators, four VCAs and a mixer
Voltage-controlled harmonic waveshaping with no input
Compares and subtracts each phase against an input signal
GRIND -> SPIN feedback turns the oscillator into a filter
Four GRIND sliders, each separately voltage-controllable
LOW range 0.1Hz-500Hz, HIGH range 10Hz-20kHz+
Tracks 4+ octaves of V/Oct
FM 1 linear or exponential (rear header), normalled to GRIND OUT
FM 2 additional exponential V/Oct input

Controls & Jacks (25)

Grind 1
Grind 2
Grind 3
Grind 4
Spin
Range
IN
Grind → Spin
Fine
Damping
FM 1
In
Out
Inject In
V/Oct In
FM 1 In
FM 2 In
Grind CV 1 In
Grind CV 2 In
Grind CV 3 In
Grind CV 4 In
Phase 0 Out
Phase 90 Out
Phase 180 Out
Phase 270 Out

How-To Guides

Quadrature sine source
Self-oscillating GRIND timbres
State-variable filter
Supersaw / metallic waveshaper
Soft sync via Inject

Explore the interactive Angle Grinder panel on BleepDex — tap any control to learn what it does.

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How-To Guides

Schlappi Engineering Angle Grinder

Features

Controls & Jacks (25)

How-To Guides

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