# 2hp — Arp - [Manual PDF](../../manuals/2hp_Arp_Manual_2023.pdf) --- [Manual PDF](https://twohp.com/modules/arp) # 2hp Arp — melodic use in a Eurorack system The **2hp Arp** is a **gate-driven arpeggiator** that turns a selected chord into a stepped **V/Oct melodic sequence**. It’s very compact, but musically it can do a lot: chord-based riffs, repeating ostinatos, pseudo-basslines, harmonic motion, and generative melody when paired with clocks, gates, modulation, and quantized pitch destinations. ## What the module does At its core, **Arp outputs pitch CV** based on: - a **selected chord** - a **root note** - an **arpeggio mode** - incoming **trigger pulses** - optional **reset pulses** - optional CV over **root** and **chord** ### Main controls and I/O - **Trig Input** - Advances the arpeggio one step per gate/trigger - Threshold: **0.4V** - **Reset Input** - Restarts the pattern at the **root note** - Threshold: **0.4V** - **Root Knob** - Sets the base pitch / chord root - **Root CV Input** - CV control over root - Range: **0V to +5V** - **Chord Knob** - Selects chord type - **Chord CV Input** - CV control over chord selection - Range: **0V to +5V** - **Mode Knob** - Selects playback direction/order - **Output** - **V/Oct pitch CV output** - Range: **0V to +5V** ## Available chords The module can arpeggiate these chord qualities: - Major - Major 7 - Dominant 7 - Minor - Minor 7 - Diminished - Half Diminished 7 - Full Diminished 7 - Augmented - Augmented 7 - Sus 4 - Sus 4 Maj 7 - Sus 4 Min 7 This makes it much more than a simple “up/down notes” utility — it’s really a **harmony-to-melody converter**. ## Available arpeggio modes Playback modes include: - Ascending one octave - Ascending two octaves - Descending one octave - Descending two octaves - Pendulum one octave - Pendulum two octaves - Random one octave - Random two octaves These modes strongly affect the melodic character: - **Ascending/descending** = orderly, classic arpeggios - **Pendulum** = more lyrical, looping shapes - **Random** = generative, less repetitive - **Two-octave** = more dramatic range and movement --- # How to use 2hp Arp for melody ## 1. Basic chord-to-melody patch This is the most direct use. ### Patch - Send a **clock or trigger sequence** to **Trig Input** - Patch **Arp Output** to your oscillator’s **V/Oct** - Send the oscillator to a **VCA/filter/voice path** - Trigger an envelope from the same clock or from a related gate source - Choose: - **Root** - **Chord** - **Mode** ### Result Each trigger advances to the next note in the chosen chord, creating a melodic line that stays harmonically coherent. ### Musical use - bass arps - plucks - techno sequences - synthwave ostinatos - Berlin-school style step motion --- ## 2. Use reset for phrase structure The **Reset input** is one of the most important features musically. ### Patch idea - Fast clock to **Trig** - Slower pulse every 4, 8, or 16 steps to **Reset** ### Result The arp restarts on the root at regular intervals, producing a repeating phrase instead of endlessly drifting. ### Why it matters Without reset, the pattern may feel more circular or continuous. With reset, it becomes more **song-like**: - downbeats land on root notes - phrases become easier to hear - basslines feel more intentional This is especially strong in: - techno - trance - arpeggiated pop lines - sequenced ambient --- ## 3. Animate harmony with Root CV The **Root CV input** lets you transpose the entire arpeggio. ### Patch idea - Send a slow sequencer, precision adder source, keyboard CV, or quantized CV to **Root CV** - Keep a steady trigger stream into **Trig** ### Result The arpeggio pattern stays structurally similar, but shifts to new tonal centers. ### Musical applications - chord progressions - key changes - moving bass foundations - verse/chorus transitions ### Example progression idea Send stepped voltages to Root CV corresponding to: - I - vi - IV - V Then set the chord quality manually or by CV. This gives you a complete **harmonic progression generator** with only a few signals. --- ## 4. Modulate chord type for harmonic movement The **Chord CV Input** is where things get especially interesting. ### Patch idea - Send a stepped CV source to **Chord CV** - Clock that CV more slowly than the arpeggio triggers ### Result The chord quality changes while the note stepping continues. ### Musical applications - alternating major/minor colors - tension/release with 7ths - unstable cinematic diminished motion - suspended chords for modal textures ### Tip For musical results, clock chord changes at slower divisions: - note changes every 16th - chord changes every bar or half-bar This creates a strong hierarchy: - fast motion = melody - slow motion = harmony --- ## 5. Build full progressions with both Root CV and Chord CV This is where Arp becomes a compact composition tool. ### Patch concept - **Trig:** steady clock - **Reset:** phrase reset every 8 or 16 steps - **Root CV:** progression source - **Chord CV:** chord-quality source - **Output:** oscillator V/Oct ### Result You get a melody that reflects: - harmonic root movement - chord quality changes - pattern direction - octave span This is enough to generate: - evolving arpeggiated hooks - soundtrack patterns - melodic techno motifs - generative tonal lines --- # Best pairings with other Eurorack modules The manual only covers the Arp itself, but musically, here’s how it works with common module types. ## With a clock source A clock or trigger sequencer is essential because Arp is **gate-driven**. Use: - master clocks - trigger sequencers - Euclidean triggers - clock dividers/multipliers - manual gate buttons ### Why The timing source determines: - note density - groove - syncopation - phrasing A rigid clock gives machine-like precision. Irregular trigger sources give broken, human, or generative melodies. --- ## With an oscillator or full voice Arp outputs **pitch CV only**, so it needs a sound source. Good destinations: - analog VCO - wavetable oscillator - FM voice - pluck voice - physical modeling voice - any full synth voice with V/Oct input ### Why Different voices change the role of the arp: - sine/triangle = bass or minimal melody - saw/pulse = classic synth arps - wavetable = modern animated sequences - FM = metallic/cinematic patterns --- ## With envelopes and VCAs To hear discrete notes, patch triggers to an envelope and VCA. ### Typical patch - Clock mult: - one copy to **Arp Trig** - one copy to **Envelope Gate/Trig** - Envelope to VCA CV - Oscillator through VCA - Arp output to oscillator pitch ### Result Each pitch step becomes an articulated note. ### Variation Use a different rhythmic trigger for the envelope than for the arp advance: - arp moves on every 16th - envelope opens only on selected steps This creates **implied melodies** and rhythmic variation. --- ## With filters If you patch the voice through a filter, you can make the melodic line feel more expressive. ### Patch ideas - envelope to filter cutoff - LFO to cutoff - accent gate to cutoff CV - reset pulse to a burst envelope affecting brightness ### Result The harmony may stay constant while timbre adds motion, making the arp more musical and less static. --- ## With sequencers Sequencers pair beautifully with Arp, especially if you use them not for direct pitch, but for **meta-control**. Use a sequencer to control: - **Root CV** - **Chord CV** - **Mode changes** via manual performance between takes - resets and phrase length ### Why this is powerful Instead of sequencing every note directly, you sequence the **rules** that generate the notes. That gives: - coherent tonal output - less programming - more happy accidents --- ## With random / sample-and-hold / chaos sources These are great for generative work. ### Good uses - random stepped CV to **Root CV** - restrained random CV to **Chord CV** - irregular gates to **Trig** - slow random pulse to **Reset** ### Result A self-moving melodic network that still sounds harmonically structured because Arp constrains note choices to chord tones. This is one of the best uses of the module: **randomness with harmonic containment**. --- ## With quantizers You may not always need a quantizer after Arp, since it already outputs pitch in a structured harmonic system. But quantizers can still help upstream or downstream. ### Useful placements - Quantize CV going into **Root CV** - Quantize external transposition sources - Use a precision adder + quantizer combo for key control ### Why This helps keep chord roots aligned to a chosen scale or song key. --- ## With precision adders / offsets A precision adder is very useful if you want to transpose the arp while preserving interval relationships. ### Use cases - add keyboard CV to Arp output - add bass transposition - layer multiple pitch influences - create call-and-response by offsetting copies --- # Melodic patch recipes ## Patch 1: Classic synth arpeggio - Clock → Trig - Reset every 8 steps → Reset - Arp Out → VCO V/Oct - Clock → Envelope trig - VCO → VCF → VCA - Set chord to **Minor 7** - Mode = **Ascending one octave** **Sound:** tight, classic, musical arp line --- ## Patch 2: Bass ostinato with harmonic change - 16th-note trigger → Trig - Bar reset → Reset - Slow sequencer → Root CV - Chord fixed to **Minor** or **Dominant 7** - Arp Out → bass oscillator **Sound:** repeating bass figure that follows a progression --- ## Patch 3: Generative ambient melody - Irregular trigger source → Trig - Slow random pulse → Reset - Slow random stepped CV → Root CV - Very slow stepped modulation → Chord CV - Mode = **Random two octaves** - Arp Out → mellow voice or resonator **Sound:** evolving melodic fragments with harmonic identity --- ## Patch 4: Suspended tension pattern - Clock → Trig - Reset every 16 steps - Chord set to **Sus 4**, **Sus 4 Maj 7**, or **Sus 4 Min 7** - Mode = **Pendulum one octave** - Bright plucked voice **Sound:** unresolved, floating melodic texture great for intros and breakdowns --- ## Patch 5: Dark cinematic motion - Clocked triggers → Trig - Root sequence moves slowly - Chord CV alternates between: - Diminished - Half Diminished 7 - Full Diminished 7 - Mode = **Descending two octaves** **Sound:** ominous, unstable, tension-heavy melodic movement --- # Performance strategies ## Use reset as a musical downbeat If you manually or rhythmically fire reset at section starts, the pattern feels intentional and anchored. ## Perform chord changes live The **Chord knob** is performance-friendly. Sweeping between major, minor, suspended, augmented, and 7th-based chords can dramatically change mood without repatching. ## Switch modes for arrangement changes Even with the same root and chord: - **Ascending** = verse energy - **Pendulum** = flowing bridge - **Random** = breakdown or ambient section - **Two-octave** = lift or climax ## Use slower modulation for structure Fast note triggers with slow root/chord modulation give a musically readable hierarchy. ## Layer multiple voices Mult the Arp output to: - a bass voice - a higher pluck voice - a delayed or reverb-heavy texture If transposed or timbrally separated, one arp stream can become a complete melodic stack. --- # Practical notes from the manual ## Voltage ranges - **Root CV:** 0V to +5V - **Chord CV:** 0V to +5V - **Output:** 0V to +5V That means it plays in a fairly standard Eurorack pitch space and should work well with most V/Oct inputs. ## Trigger/reset thresholds - **Trig threshold:** 0.4V - **Reset threshold:** 0.4V So standard Eurorack triggers and gates should work fine. ## Size and power - **Width:** 2HP - **Depth:** 45mm - **Power:** +12V 40mA, -12V 3mA, +5V 0mA Very easy to fit into a small system, especially if you want a compact melodic utility. --- # Bottom line The **2hp Arp** is best thought of as a **melodic engine** rather than just an effect or helper module. It works especially well when combined with: - a **clock/trigger source** - a **voice or oscillator** - **envelopes + VCA** - optionally a **sequencer** for root/chord movement - optionally **random/modulation** sources for generative behavior Its strength is that it creates melodies that are: - rhythmically driven - harmonically constrained - easy to transpose - compact to patch - performable in real time So if you want **musical melodic content quickly**, this module is excellent for: - arpeggios - ostinatos - basslines - harmonic motifs - generative tonal melodies --- [Generated With Eurorack Processor](https://github.com/nstarke/eurorack-processor)