# Schlappi Engineering — Angle Grinder - [Manual PDF](../../manuals/angle_grinder_manual_20181022.pdf) --- [Angle Grinder Manual PDF](#) # Schläppi Engineering Angle Grinder — melodic use analysis The attached manual is for **one module**: **Schläppi Engineering Angle Grinder**. So rather than “how these modules can be used together,” the useful framing here is: - how the **internal sections** of Angle Grinder work together - how to patch it with the rest of a Eurorack system to create **melodic material** - what kinds of **pitched roles** it can play in a musical patch --- ## What Angle Grinder is, musically Angle Grinder is not just a weird distortion/filter. It is really **three melodic-capable tools in one**: 1. **Quadrature sine VCO / LFO** 2. **State-variable-ish filter** 3. **Voltage-controlled waveshaper / nonlinear feedback processor** That makes it useful for melody in several different ways: - as a **primary oscillator** with 1V/oct tracking - as a **companion oscillator** for phase-related voices - as a **harmonic animation source** for otherwise plain waveforms - as a **filter voice** that can be “played” by resonance/feedback behavior - as a **subtle or aggressive timbral layer** that follows melodic pitch The big concept of the module is the interaction between: - **SPIN** = the oscillator/filter core - **GRIND** = comparator + VCA + subtractive waveshaping/feedback network This interaction is what turns a simple pitched tone into something alive and musically rich. --- ## Key manual takeaways for melodic patching From the manual: - **Tracks 4+ octaves at the V/OCT input** - **High range:** about **10 Hz to over 20 kHz** - **Low range:** about **0.3 Hz to over 600 Hz** - **Four phase-related outputs**: - in oscillator mode: **0°, 90°, 180°, 270°** - in filter mode: **Low Pass, Band Pass, High Pass, Inverted Band Pass** - **Sine outputs** are **5 Vpp** - **GRIND/filter outputs can get much hotter**, up to around **22 Vpp** - **FM1** can be linear or exponential via rear jumper - **FM2** is additional exponential pitch CV - **INJECT** can feed SPIN directly, bypassing GRIND - **FM1 is normalled to GRIND OUT**, which matters a lot for tuning That last point is especially important for melodic use: if you want clean pitch tracking, **turn FM1 down unless you intentionally want self-modulated chaos**. --- # How the two sections work together for melody ## 1. SPIN as the pitch source SPIN is a **quadrature sine oscillator**, which means it produces four sine waves at the same frequency but shifted by 90° relative to each other. For melody, this gives you: - a **clean fundamental tone** - four related outputs that can be: - mixed for different timbres - sent to different VCAs/filters - used as phase-offset modulation sources - treated as separate “voices” that still feel unified Because it tracks 1V/oct over several octaves, SPIN can absolutely serve as a **pitched melodic oscillator**. ### Strong melodic use cases - lead voice - bass voice - tuned FM source - chord-ish layered sine stack through further processing - quadrature modulation source for animated stereo melodic patches --- ## 2. GRIND as harmonic sculptor GRIND compares the SPIN phases against an input, creates square-ish control shapes, and subtracts them from the input. In plain musical terms: - it can turn simple tones into **edgy, metallic, vocal, pyramidal, stepped, or tearing waveforms** - it can create **harmonic complexity that still follows pitch** - it can act like a **voltage-controlled timbre engine** This is exactly the kind of thing that makes a melody feel expressive rather than static. For melodic composition, GRIND is especially good at: - adding controllable overtone motion to a pitched oscillator - creating brighter transients on note attacks - evolving a bassline from sine to snarling shape - producing unstable but repeatable timbres when under CV control --- ## 3. GRIND→SPIN as “playable instability” The **GRIND -> SPIN** control feeds the GRIND output back into the oscillator/filter core. This is the musical magic zone. At low amounts: - subtle enrichment - dynamic asymmetry - controlled growl At medium amounts: - animated harmonic movement - unstable but still pitch-centered tones - pseudo-resonant behavior At high amounts: - the oscillator can be overwhelmed and shift toward **filter-like behavior** - tones can become noisy, percussive, or semi-chaotic - pitch may become less stable, but this can be musically great for accents and transitions For melody, this means you can treat GRIND->SPIN as a **timbre-performance control**: - lower for stable notes - higher for choruses, fills, or dramatic phrases --- # Best melodic roles for Angle Grinder ## A. Primary melodic oscillator This is the most straightforward use. ### Patch idea - Sequencer 1V/oct → **V/OCT** - Envelope → VCA controlling audio level downstream - Take **0° output** or **GRIND OUT** as main audio - Keep **FM1 down** - Tune with **SPIN** and **FINE** - Use **GRIND sliders** for timbre shaping ### Musical result - Clean sine-based melodies if you use SPIN outputs directly - Rich, animated leads or basses if you use GRIND OUT ### Why it works You get pitch stability from SPIN and character from GRIND. --- ## B. Melodic oscillator with animated timbre Because each GRIND lane has its own slider and CV input, you can move the harmonic structure over time. ### Patch idea - Sequencer → **V/OCT** - Slow envelope/LFO/sequence rows → one or more **GRIND CV inputs** - Main audio from **OUT** - Optionally use a separate envelope to control final VCA ### Musical result Each note can have: - different brightness - different edge - different attack contour - timbral movement across a phrase This is ideal for: - acid-adjacent leads - morphing basslines - synthetic plucks with internal animation --- ## C. Dual-role melody + modulation source Since SPIN has four phase outputs, you can use one as audio and others as modulation tied to the same pitch. ### Patch idea - 1V/oct → V/OCT - **0° output** → audio path - **90° / 180° / 270° outputs** → modulate: - panning - wavefolder symmetry - filter cutoff - VCA level on parallel voice ### Musical result The melody itself drives its own movement. This creates very coherent patches where: - every note has internal motion - stereo shifts feel locked to the pitch - supporting modulation feels musically related rather than arbitrary This is one of the most special melodic uses of Angle Grinder. --- ## D. Melodic filtering / pingable timbre voice When SPIN is damped or sufficiently disrupted by GRIND feedback/input, it behaves more like a filter core. With the right external oscillator, Angle Grinder becomes a very unusual **melodic filter voice**. ### Patch idea - Send a tuned VCO or harmonically rich source into **IN** - Turn **GRIND -> SPIN** clockwise - Add some **DAMPING** - Use the SPIN outputs as: - low pass - band pass - high pass - inverted band pass ### Musical result - moving resonant tones - formant-like melodic filtering - unstable but expressive spectral shifts - pseudo-physical or vocal textures This works great when the melody is carried by another oscillator and Angle Grinder becomes the **character voice**. --- ## E. Soft-sync melodic voice with INJECT The **INJECT** jack directly hits the SPIN core and can be AC- or DC-coupled. The manual says AC mode is default and acts like a **soft sync-like effect**, especially with square or saw input. ### Patch idea - Sequencer → V/OCT on Angle Grinder - Another oscillator’s saw or square → **INJECT** - Main audio from SPIN output or GRIND OUT ### Musical result - stable pitch with reset-like articulation - animated sync-ish harmonics - sharper melodic presence without standard hard-sync harshness This is excellent for: - leads - sync bass - aggressive arpeggios --- # Practical melodic patch recipes ## 1. Clean sine lead **Goal:** pure, stable melodic line **Patch** - Sequencer → V/OCT - 0° output → VCA → mixer - Envelope → VCA CV - FM1 fully down - GRIND sliders down or unused - DAMPING low / oscillator mode active **Result** - very pure sine lead or bass - good for sub lines, FM carrier duty, or minimal melodies --- ## 2. Animated bass voice **Goal:** bassline that moves harmonically while staying pitch-centered **Patch** - Sequencer → V/OCT - OUT → lowpass filter or LPG → VCA - One envelope or sequencer lane → GRIND CV 1 - Another modulation source → GRIND CV 2 - Keep GRIND->SPIN low to medium - Use one or two sliders up **Result** - bass with evolving edge - can move from rounded to biting across a phrase - especially good for techno, EBM, industrial, electro --- ## 3. Phase-based stereo melody **Goal:** wide melodic voice from one oscillator **Patch** - Sequencer → V/OCT - 0° output → left voice chain - 180° output → right voice chain - Or 90° and 270° to two VCAs/panners - Use same envelope for both, or offset them slightly **Result** - natural stereo spread - strong mono relationship but lively width - beautiful for drones, ambient melodies, and glassy tuned textures --- ## 4. Four-note articulated patch from one pitch source **Goal:** one melodic line driving a complex ensemble feel **Patch** - Sequencer → V/OCT - Send 0°, 90°, 180°, 270° to four different destinations: - four VCAs - four filters - four wavefolders - Modulate each destination differently - Mix them back together **Result** - one pitch source, but layered motion - pseudo-ensemble or rotating timbre cloud - excellent for melodic ostinatos --- ## 5. Harmonic melody processor **Goal:** use Angle Grinder to transform another melodic oscillator **Patch** - External oscillator carrying the melody → IN - Set SPIN to LFO or audio rate depending desired effect - Listen to OUT - Modulate GRIND sliders/CV - Keep GRIND->SPIN low for processing, higher for feedback complexity **Result** - supersaw-like shimmer at low internal rates - metallic sidebands and tearing overtones at audio rates - melody remains recognizable but gets a distinct synthetic personality This is especially powerful when you already have a favorite VCO but want a more original melodic timbre. --- ## 6. Filtered melody with nonlinear resonance **Goal:** melodic line with unstable resonant animation **Patch** - External VCO → IN - Use GRIND->SPIN at medium-high setting - Add DAMPING to move away from pure oscillation - Take LP/BP/HP outputs from SPIN - Sequence/filter the external VCO as normal **Result** - animated filtering that feels halfway between a filter, resonator, and feedback network - great for leads that need movement without adding many extra modules --- ## 7. Self-voicing chaotic melody **Goal:** unstable but tunable lead voice **Patch** - Sequencer → V/OCT - No input patched, or experiment with IN turned up as manual suggests - Use OUT as audio - Raise one or more GRIND sliders - Explore GRIND->SPIN and DAMPING carefully - FM1 down unless intentionally using self-feedback FM **Result** - highly characterful, almost broken-waveform tones - can sound like sync, folding, PWM, and comparator distortion all at once - great for aggressive hooks and industrial melody lines --- # How to keep it melodic instead of chaotic Angle Grinder can go wild quickly. If your goal is melody, these practices help a lot. ## 1. Turn FM1 down for pitch tracking The manual explicitly warns that **FM1 is normalled to GRIND OUT**. So if nothing is plugged in and FM1 is up, the oscillator is self-modulating. That is fun, but not ideal if you want: - precise tuning - consistent intervals - stable bass So for melodic work: - **start with FM1 fully CCW** --- ## 2. Start from SPIN outputs, then add GRIND If you need a reliable melodic basis: 1. get the pitch right on 0° output 2. confirm tracking 3. then bring in GRIND OUT or feedback This prevents losing the musical center too early. --- ## 3. Use fewer sliders first The manual’s oscilloscope examples show that each slider introduces a distinct shaping contribution, and combinations get more complex. For melody: - begin with **one slider** - then try **two adjacent sliders** - only then go to all four This keeps the overtone structure more readable. --- ## 4. Use GRIND->SPIN like a macro performance control Instead of setting it high all the time, automate or perform it. Best use: - lower during verse - rise during fill - spike for transitions - pull back for pitch clarity --- ## 5. Separate “pitch CV” from “timbre CV” Use: - **V/OCT / FM2** for pitch-related control - **GRIND CV inputs** for timbre-related control This makes the module much easier to compose with. --- # Where Angle Grinder shines in melodic genres ## Excellent for - industrial techno - EBM - electro - dark ambient - experimental pop - IDM - cinematic tension music - acid-adjacent bass and lead work - noise-informed but tonal music ## Less naturally suited for - very pristine traditional subtractive lead patches - ultra-precise tonal polyphony - delicate, perfectly repeatable analog sweet-spot patching It can still do subtler work, but its personality is in **animated nonlinearity**. --- # Best musical pairings in a wider Eurorack system Even though only one module manual was attached, Angle Grinder pairs especially well with: ## Sequencers For obvious melodic use: - 1V/oct lines - sequenced timbre CV to GRIND lanes - transposition and accent tracks ## VCAs / LPGs Essential to shape notes dynamically after the often-hot outputs. ## Envelopes Very useful for: - note articulation - per-note grind animation - feedback depth changes ## Filters If using GRIND OUT as a main oscillator, a downstream filter can tame or spotlight specific overtones. ## Wavefolders / distortion Angle Grinder already shapes heavily, but subtle extra processing can create very rich leads. ## Delays / reverbs The phase outputs into stereo effects can sound huge and highly musical. ## Precision adder / quantizer Helpful if you want to keep complex Angle Grinder patches locked into tonal material. --- # Most musically useful outputs for melody ## 0° output - best starting point for pitch - cleanest reference - ideal for tuning and stable melodic work ## 90° / 180° / 270° - alternate voices - stereo companions - modulation tied to pitch - parallel processing ## OUT / GRIND OUT - most characterful melodic audio output - best for aggressive basses and leads - can get very hot; attenuate if needed ## Filter outputs when in filter behavior - best for spectral melodies - unusual formants - feedback-rich tonal coloration --- # Three high-value melodic workflows ## Workflow 1: Stable melody, unstable timbre - Pitch from V/OCT - Audio from GRIND OUT - FM1 off - Moderate slider use - GRIND CV animated by envelopes/LFOs This is probably the most generally useful mode. ## Workflow 2: One oscillator, many related voices - Use multiple SPIN outputs in parallel - Different processing per phase - Common pitch sequence This is excellent for stereo and layered arrangements. ## Workflow 3: External melody into Angle Grinder processor - Use another VCO for the main melody - Feed it to IN - Use Angle Grinder as wave-transformer/filter-feedback network This is the best option if you want Angle Grinder’s character without relying on it as the only pitch source. --- # Bottom line **Angle Grinder is absolutely capable of creating melodic components**, but it is most rewarding when treated as a **performance-oriented timbral oscillator/filter hybrid** rather than a plain voice. Its strongest melodic uses are: - **quadrature sine VCO** for tuned melodic lines - **animated waveshaper** for expressive bass and lead timbres - **phase-related multi-output source** for stereo or layered melodic structures - **soft-sync / injected oscillator** for sharper harmonic articulation - **nonlinear filter/resonator** for spectral melodic processing If you want clean melody, start simple: - V/OCT in - FM1 down - monitor 0° output - add GRIND gradually If you want memorable melody, lean into what makes Angle Grinder special: - CV the GRIND lanes - exploit the four phases - perform GRIND->SPIN - use INJECT and feedback as compositional tools It is a module that can make a sequence sound less like “notes from an oscillator” and more like a **living mechanical voice**. --- [Generated With Eurorack Processor](https://github.com/nstarke/eurorack-processor)