# Schlappi Engineering — Three Body - [Manual PDF](../../manuals/three_body_manual_01302023a.pdf) --- [Three Body Manual (Schlappi Engineering)](attachment) # Using the Schlappi **Three Body** for melodic music The **Three Body** is a 3-oscillator digital modulation complex oscillator focused on **phase modulation, linear FM, ratio relationships, and stereo motion**. For melodic use, its big strength is that the three oscillators can behave either as: - **independent VCOs/LFOs** - **ratio-locked harmonic oscillators** - **cross-modulating carriers/modulators** - **a stereo melodic voice with internal normalization** That makes it especially good for: - harmonic lead voices - metallic but tunable FM tones - animated basses - chord / pseudo-paraphonic interval structures - arpeggiated ratio melodies - tempo-locked melodic modulation --- ## What the module fundamentally is Three Body contains: - **1 center oscillator** - **2 outer oscillators** Each oscillator can run in: - **FREE mode** Like a normal oscillator/LFO with pitch controlled by coarse/fine and V/oct. - **RATIO mode** The oscillator tracks another oscillator or external sync input at a **multiplied or divided ratio**. Each oscillator also supports modulation: - **phase modulation** - **frequency modulation** - **sync / tracking** The center oscillator is special because it has: - **sine + cosine** - **saw + cosaw** - dual phase inputs from the two outer oscillators - especially strong stereo applications --- # Why this module is musically useful for melody For melodic work, the key manual points are: 1. **Outer oscillators can track the center oscillator in ratio mode** with no cable inserted into their sync jacks. 2. This creates stable **musical intervals and harmonic series relationships**. 3. The center oscillator can remain your pitch reference while the outer oscillators become: - harmonics - subharmonics - changing interval voices - FM operators 4. The module supports **1V/oct on the transpose and individual V/Oct/Ratio inputs**, so it can still play from sequencers and keyboards. 5. You can modulate the ratio CV inputs for **melodic interval animation**, not just timbre. In practice, it can behave like: - a **3-oscillator harmonic voice** - a **DX-style operator cluster with analog patchability** - a **subharmonic chord machine** - a **stereo melodic oscillator** --- # Most important melodic patching ideas from the manual ## 1. Harmonic interval voice This is the most immediately musical use. ### Patch - Set **center oscillator** to: - **FREE** - **HIGH** - Patch your sequencer pitch CV to **TRANSPOSE** - Set one or both **outer oscillators** to: - **RATIO** - Listen to: - center sine/triangle - one or both outer sine outputs ### Result The center oscillator plays the melody. The outer oscillators become interval voices related by integer multiply/divide settings. ### Musical use You get: - octaves - fifths - fourths - more complex overtone relationships - moving chord-like stacks from a single pitch line ### Good settings With divide at 1 and multiplication changing: - 1:1 unison - 2:1 octave - 3:2 fifth-ish relationships depending on settings - harmonic series climbing This is ideal for: - bass + upper harmonic - drone melodies - simple two-note harmonization - pseudo chords from one sequencer lane --- ## 2. Subharmonic melody generator The manual makes clear that in ratio mode the oscillators can also **divide**. ### Patch - Center oscillator = **FREE, HIGH** - Outer oscillator(s) = **RATIO, DIV** - Sequence the center from **TRANSPOSE** - Take audio from outer oscillators ### Result Instead of upper harmonics, you get **subdivided pitch relationships**. This can feel like: - suboctaves - undertone series - organ-like interval structures - Subharmonicon-style harmonic motion ### Musical use Great for: - dark bass lines - medieval/drone harmony - thick mono leads - pseudo counterpoint from one CV source --- ## 3. Ratio-CV arpeggiation One of the most interesting melodic functions in the manual: feed CV into the **V/OCT RATIO** input of an outer oscillator. ### Patch - Center oscillator = melodic source in FREE mode - Outer oscillator = RATIO mode - Send a slow stepped CV, envelope, or sequencer row into **outer V/OCT RATIO** - Attenuate carefully ### Result The outer oscillator changes multiplier or divider values, creating **discrete interval jumps** relative to the center pitch. ### Musical effect This creates: - arpeggiation - harmonic melody doubling - interval sequencing - pseudo chord inversions If modulation is subtle, it can hop between a few ratio values and feel like a musically locked harmony line. This is one of the strongest ways to get **melodic movement without repitching the root**. --- ## 4. Three-note harmonic stacks from one sequence Because all oscillators can be heard independently, Three Body can produce three related musical lines. ### Patch - Sequencer CV to **TRANSPOSE** - Center oscillator = **FREE** - Left oscillator = **RATIO** - Right oscillator = **RATIO** - Use different mult/div settings on left and right - Take all three sine outputs into a mixer ### Result A single melodic line becomes a 3-voice interval stack. ### Musical use This gives: - instant triad-ish structures - open fifth drones - stacked harmonics - organ/register sounds It won’t always map to equal-tempered harmony in a traditional way, because ratio relationships are just intonation/harmonic-based rather than fixed semitone transposition. But that’s often exactly why it sounds rich. --- ## 5. Stereo melodic voice The center oscillator has special outputs: - **SINE** - **COSINE** - **SAW** - **COSAW** The manual explains that these are phase-related outputs designed for wide stereo use, especially under phase modulation. ### Patch - Use center **SINE** to left channel - Use center **COSINE** to right channel - Or use **SAW / COSAW** - Bring up **PHASE INDEX 1** and **PHASE INDEX 2** - Let outer oscillators modulate the center ### Result A single melodic line becomes a **wide stereo voice** with internal timbral animation. ### Musical use Excellent for: - leads - pads - drones - melodic ambient voices - stereo bass textures This is especially nice because you can keep the melody simple while the timbre blooms around it. --- ## 6. Tuned FM voice The manual strongly supports **linear FM in ratio mode** for harmonic sounds. ### Patch - Center oscillator = base pitch source - Outer oscillators = **RATIO + LIN FM** - Outer oscillators tuned above center with mult settings - Listen to outer sine outputs - Bring up their **FM INDEX** - Optionally modulate FM index with envelopes ### Result You get classic **tuned FM sidebands** with better harmonic stability when simple ratios are used. ### Musical use This is ideal for: - bells - electric piano-ish tones - glassy leads - metallic basses - plucked digital tones The manual notes an important rule: - for harmonic audio-rate modulation, use **simple ratios** So melodic patches are strongest when carrier/modulator relationships are kept simple. --- ## 7. Animated timbre while pitch stays stable A major musical advantage of **phase modulation** over FM, according to the manual, is that PM avoids some pitch drift and DC-offset pitch problems. ### Patch - Center oscillator is your audible melodic output - Outer oscillators modulate center via **PHASE 1** and **PHASE 2** normalization - Sequence only the center with **TRANSPOSE** - Use the outer oscillators either: - ratio-locked for harmonic PM - or free-running for more unstable colors ### Result The melody remains more stable while timbre shifts dramatically. ### Musical use This is ideal when you want: - recognizably pitched melody - evolving harmonics - strong articulation without filter reliance It’s a very effective way to create expressive melodic phrases that sound “complex oscillator” but remain playable. --- # Internal normalizations that matter for melodic patching The manual describes several normalizations that make melodic patching easy without many cables. ## Modulation normalization - **Center oscillator PHASE inputs** are normalized from the two outer sine outputs - **Outer oscillator FM inputs** are normalized from the center oscillator: - left gets center sine - right gets center cosine - **Outer oscillator PHASE inputs** are normalized from the opposite outer sine ## Ratio normalization - Outer oscillators in **RATIO mode** track the center oscillator if no cable is inserted in their sync inputs ### Why this matters This means you can quickly get: - a harmonic 3-oscillator voice - stereo FM pair - center-carried melody with outer interval tones - cross-modulated harmonic stack without much patching. --- # Best melodic roles for each oscillator ## Center oscillator Best as: - root pitch - main melodic oscillator - stereo voice source - PM target - master for harmonic tracking Use outputs: - **sine/cosine** for cleaner stereo melody - **saw/cosaw** for richer harmonic material - **triangle** for a middle-ground tone ## Outer oscillators Best as: - harmony oscillators - FM carriers - PM modulators - ratio-derived intervals - subharmonic voices Use outputs: - **sine** for cleaner FM/melodic tones - **saw/triangle/square** for more aggressive layered voicing --- # Practical melodic patch recipes ## Patch 1: Simple harmonic lead - Center: FREE / HIGH - Left: RATIO / MULT - Right: RATIO / MULT - Sequencer to TRANSPOSE - Mix center sine + left sine + right sine - Set outer ratios to octave/fifth-ish relationships **Sound:** harmonically rich mono/stereo lead from one sequence. --- ## Patch 2: Subharmonic bass melody - Center: FREE / HIGH - One outer oscillator: RATIO / DIV - Sequence center pitch from TRANSPOSE - Listen mainly to the divided outer oscillator plus some center sine **Sound:** deep, organ-like bass with strong tonal center. --- ## Patch 3: Melodic stereo PM lead - Center: FREE / HIGH - Outer oscillators: RATIO - Listen to center **SINE + COSINE** - Raise **PHASE INDEX 1/2** - Sequence center with TRANSPOSE **Sound:** wide stereo melodic voice with animated timbral motion. --- ## Patch 4: FM pluck / bell - Center: lowish pitch - Outer oscillators: RATIO + LIN - Divide fully down, multiply above noon - Listen to outer sine outputs - Envelope into **FM INDEX** - Sequence pitch with TRANSPOSE **Sound:** tuned digital percussion, mallets, bells, sharp plucks. --- ## Patch 5: Arpeggiated interval companion - Center sequenced melodically - Right oscillator in RATIO - Stepped CV into right **V/OCT RATIO** - Heavily attenuate - Mix center + right outputs **Sound:** one melody plus automatically shifting interval accompaniment. --- ## Patch 6: Pseudo chord machine - Center sequenced - Left in ratio-div - Right in ratio-mult - Tune by ear to consonant relationships - Mix all three outputs **Sound:** evolving 3-note harmonic structures from one CV line. --- # Melodic strategy: when to use FREE vs RATIO ## Use FREE mode when you want: - traditional VCO behavior - exact sequencer tracking - independent pitch lines - LFO duties - looser, less locked harmonic behavior ## Use RATIO mode when you want: - consonant interval relationships - harmonic series control - subharmonic structures - stable audio-rate modulation - one oscillator to derive melody-related voices from another For melodic composition, **RATIO mode is the secret weapon**. --- # How to keep it musical The manual gives several strong hints. ## 1. Use simple ratios For harmonic results: - 1:1 - 2:1 - 3:2 - 4:3 - 5:4 - 6:5 These make FM/PM spectra feel pitched rather than chaotic. ## 2. Keep cross modulation moderate Too much cross phase modulation can become: - noisy - shrieking - unstable A little adds life; too much destroys note identity. ## 3. Linear FM is strong The manual says linear FM is amplified strongly internally. Small knob movements can have a big effect. For melodic use: - start low - increase slowly - use envelopes on index rather than constant high depth ## 4. Phase modulation is better for stable pitch color If you want the note center to remain more obvious while adding harmonics, use PM rather than deep FM. ## 5. Use sine outputs first For tuning and harmonic listening: - start with sine outputs - move to saw/cosaw later if you want more bite --- # External tracking for melodic systems The manual also notes that in **RATIO mode**, inserting an external signal into **SYNC** lets an oscillator track that external source. ### Musical uses You can use this to: - harmonize another oscillator in your system - derive intervals from an external VCO - create tempo-locked LFO divisions/multiplications - build harmonic layers around another module’s voice ### Important caveat Tracking is best with: - simple waveforms - monophonic sources - steady signals For audio harmonization, period tracking is preferred over PLL. --- # Good compositional uses in a eurorack patch ## As a lead voice Use center sine/cosine stereo pair, outer oscillators as ratio PM sources. ## As a bass voice Use center as root, outer in divide mode for subharmonics, maybe add a little PM for growl. ## As a chord source Use all three oscillators mixed together with different ratios. ## As an FM melody generator Use outer oscillators as linear FM carriers and center as common modulator. ## As an accompaniment generator Use one sequencer lane into transpose, then animate outer ratio CV inputs for shifting harmonies. ## As a drone/melodic hybrid Sequence the center slowly, let outers track at ratios, cross-modulate lightly. --- # Limitations to be aware of Based on the manual: - It is **not** a conventional equal-tempered chord oscillator. - Ratio relationships are often **just-intonation / harmonic** rather than semitone-quantized. - Deep FM or cross modulation can easily become: - noisy - unstable - inharmonic - Audio-rate FM wants the modulator lower than the carrier for expected behavior. - Heavy PM can become wavefold-like and noisy. These are not flaws—they are the character of the module. --- # Best overall melodic workflows ## Workflow 1: One-sequence harmonic voice 1. Sequence TRANSPOSE 2. Center in FREE 3. Outer oscillators in RATIO 4. Mix three outputs 5. Adjust mult/div for harmonic intervals This is the most straightforward melodic use. ## Workflow 2: Stereo melodic timbre voice 1. Sequence center oscillator 2. Listen to center sine/cosine 3. Outer oscillators modulate center phase 4. Keep ratios simple 5. Use envelopes on indexes This gives an animated modern melodic sound. ## Workflow 3: FM operator cluster 1. Center as modulator 2. Outer oscillators as ratio-locked carriers 3. Listen to outer sines 4. Envelope FM index 5. Tune ratios musically This is the most “digital synth” style use. --- # Bottom line The **Schlappi Three Body** is extremely strong for melodic composition if you think of it as a **harmonic relationship generator**, not just a weird modulation oscillator. Its most musical strengths are: - **ratio-locked harmony** - **subharmonic and overtone interval creation** - **stereo phase-modulated melodic voices** - **tunable FM tones** - **one-sequence-to-many-related-pitches patching** If you want, I can also turn this into: 1. a **“best melodic patches” cheat sheet**, 2. a **signal-flow diagram**, or 3. a **genre-oriented guide** like *techno / ambient / electro / soundtrack* uses for Three Body. [Generated With Eurorack Processor](https://github.com/nstarke/eurorack-processor)