# 2hp — 3 to 1 - [Manual PDF](../../manuals/3_To_1_Manual.pdf) --- # [Manual PDF](#) This manual covers the **2hp 3:1**. ## What this module does musically The **3:1** is not a pitch generator by itself. It is a **voltage-controlled gate/trigger router and combiner**. That means its role in melodic patching is to decide: - **which rhythmic source is allowed through** - **when a melodic event happens** - **how multiple rhythmic layers are combined** - **how selection changes over time via CV** So in a melodic system, the 3:1 is best understood as a **melody animator**, not a melody source. It helps create melodic components by shaping **when notes occur**, **which sequence is heard**, and **how phrasing evolves**. ## Key functions from the manual - **3 inputs** for gates/triggers: **IN 1, IN 2, IN 3** - **1 output**: **OUT** - **Voltage-controlled selection** via: - **SEL knob** - **SEL CV** input, 0–5V, added to the knob position - **Two modes** - **Switch mode**: routes the currently selected input to the output - **Sum mode**: combines selected inputs and outputs **5 ms triggers** regardless of input gate length ## Why that matters for melody Melody in modular is usually a combination of: 1. **Pitch CV** 2. **Timing / gates** 3. **Articulation** 4. **Variation over time** The 3:1 directly affects items 2–4. If you pair it with: - a sequencer, - a quantizer, - a sample-and-hold, - an envelope/VCA/voice, - or multiple clock/gate sources, then the 3:1 becomes a very useful tool for building **musical phrasing and note selection logic**. --- ## Best ways to use the 3:1 for melodic components ## 1. Switching between different melodic rhythms Patch: - **IN 1** = simple clock (quarter notes) - **IN 2** = divided clock (half notes or dotted rhythm) - **IN 3** = more active trigger pattern - **OUT** = sequencer advance, quantizer trigger, envelope gate, or voice trigger - **SEL CV** = slow LFO, stepped random, or another sequencer row ### Result Your pitch source stays the same, but **the rhythm that triggers notes changes over time**. This creates: - phrase variation - call-and-response structures - evolving melodic density ### Musical use A simple 8-step melody can feel much more alive if the trigger rhythm changes every bar or every few beats. --- ## 2. Switching between multiple sequencers or pitch-event lanes Even though the 3:1 switches **gates**, that still helps when running several melodic sources in parallel. Patch: - Sequencer A pitch CV -> oscillator pitch - Sequencer B pitch CV -> precision adder/switch/mixer path - Sequencer C pitch CV -> another melodic lane - Their corresponding gate outputs -> **IN 1, IN 2, IN 3** - **OUT** -> envelope or LPG trigger - Use the same selection logic elsewhere in the patch to decide which pitch lane is active ### Result The 3:1 can act as the **rhythmic selector** that determines which melodic lane is currently articulated. This is especially effective if: - only one pitch source is active at a time, - or each gate source corresponds to a different register, transposition, or voice. ### Musical use You can create the impression of one melody “changing personality” by switching among: - sparse bass notes - midrange motif - high accent notes --- ## 3. Creating melody from one pitch source plus three trigger logics A common modular trick: - one pitch CV source generates note values - triggers determine **which notes are actually heard** Patch: - Random stepped CV or sequencer pitch -> quantizer -> oscillator pitch - **IN 1** = regular clock - **IN 2** = Euclidean rhythm - **IN 3** = manual gate / burst / irregular trigger source - **OUT** = sample-and-hold clock, quantizer trigger, or envelope trigger ### Result The 3:1 chooses how the pitch stream is articulated. The same stored pitch material produces very different melodies depending on trigger selection. ### Why this is strong In modular, changing trigger structure often changes perceived melody as much as changing notes. --- ## 4. Voltage-controlled phrase morphing Because **SEL CV** accepts 0–5V and is added to the knob position, you can automate which input is selected. Patch: - **IN 1** = rhythm for verse - **IN 2** = rhythm for variation - **IN 3** = dense fill pattern - Slow modulation into **SEL CV** - **OUT** -> melodic voice envelope ### Result The patch slowly drifts between different melodic articulations. ### Good modulation sources - slow triangle LFO - stepped random - sequencer CV row - envelope from another voice - keyboard/mod wheel CV ### Musical use This gives you: - phrasing changes - section transitions - fills and emphasis without repatching --- ## 5. Gate summing mode for richer melodic trigger generation In **sum mode**, multiple selected channels are combined and the output becomes **5 ms triggers**. This is very useful for melodic patching because many pitch devices prefer short triggers: - sample & hold - sequencers with step advance - quantizers with trigger input - envelope generators for plucky notes Patch: - **IN 1** = base clock - **IN 2** = off-beat syncopation - **IN 3** = ratchet or accent trigger - Set module to **sum mode** - Use **SEL/SEL CV** to determine how many sources are active - **OUT** -> sample-and-hold clock, envelope trigger, or sequencer advance ### Result As selection increases, your melody becomes more active because additional trigger streams are included. ### Manual behavior that matters In sum mode: - far left = **IN 1 selected** - far right = **IN 1 + IN 2 + IN 3 selected** So the knob/CV can act like a **density control** for note events. ### Musical use This is one of the strongest melodic applications of the module: - low selector setting = sparse melody - medium = more notes - high = energetic fills and ornamentation --- ## 6. Turning long gates into short melodic triggers The manual notes that in **sum mode**, the output emits **5 ms trigger signals regardless of input pulse width**. That means you can feed it long gates from: - keyboard gate - sequencer gate - clock divisions with long pulse widths and get short, clean triggers out. ### Why this helps melody Short triggers are often better for: - plucked envelopes - precise sample-and-hold updates - advancing sequencers cleanly - clocking quantized random voltages ### Patch idea - Long gates from three phrase sources into IN 1–3 - Sum mode - OUT clocks a sample-and-hold that samples a changing CV - Quantizer after sample-and-hold - Quantized output to oscillator ### Result The 3:1 becomes a **melodic event conditioner**, converting broad gate structures into crisp note triggers. --- ## 7. Building melodic fills and accents Patch: - **IN 1** = main melody trigger stream - **IN 2** = occasional fill triggers - **IN 3** = manually tapped gate button or burst generator - **OUT** = envelope trigger for lead voice Use: - **switch mode** for hard switching between normal phrase and fill phrase - **sum mode** for layering fills on top of the main phrase ### Result You can generate: - temporary melodic embellishments - phrase endings - accent clusters - dynamic lead variations --- ## 8. Using the 3:1 to control when a sequencer advances Instead of sending OUT directly to a voice, use it to **clock a sequencer** or **advance a shift register**. Patch: - **OUT** -> sequencer clock in - Sequencer CV out -> quantizer/oscillator - IN 1–3 fed by different clocks/rhythms ### Result The module determines not just when notes fire, but **when the melody itself moves to the next pitch**. This can create: - held notes - rushed notes - syncopated advancement - structural rhythmic variation in the melodic line ### Especially useful with - 8-step sequencers - Turing machine style modules - shift registers - sample-and-hold melodic patches --- ## 9. Creating call-and-response melodic structures Patch: - **IN 1** = sparse trigger pattern for phrase A - **IN 2** = contrasting trigger pattern for phrase B - **IN 3** = denser trigger pattern for answer/fill - **OUT** = melodic voice trigger - **SEL CV** driven by a slower sequence or manual performance gesture ### Result The same pitch source can sound like it’s speaking in alternating phrases. This is a very musical use because melody is often more about **phrasing** than raw note content. --- ## 10. Manual performance control over melody density and phrase choice The **SEL knob** is performable. ### In switch mode You can manually choose which rhythmic pattern drives the melody. ### In sum mode You can manually increase the number of active trigger sources, effectively opening up note density. This makes the 3:1 a strong **live performance utility** for melodic sets: - select sparse rhythm for breakdown - switch to syncopated pattern for groove - add combined triggers for climax --- ## Important constraints from the manual A few practical points: - Inputs are for **gate/trigger signals**, threshold **2.5V** - **SEL CV** range is **0–5V** - **OUT** range is **0–5V** - In **switch mode**, OUT mirrors the selected input - In **sum mode**, OUT emits **5 ms triggers** - The module does **not** process pitch CV directly So if your goal is melodic content, you’ll want to pair the 3:1 with at least one of these: - sequencer - quantizer - random voltage source - sample-and-hold - oscillator + envelope/VCA - clock divider / logic / trigger sequencer --- ## Three especially musical patch recipes ## Patch 1: Evolving quantized random melody - Noise/random CV -> sample-and-hold input - **3:1 OUT** -> sample-and-hold clock - Sample-and-hold -> quantizer -> oscillator pitch - IN 1 = steady clock - IN 2 = swung or divided rhythm - IN 3 = burst/irregular trigger - SEL CV = slow random or LFO ### What happens The 3:1 changes when new notes are sampled, creating an evolving melody with shifting rhythmic character. --- ## Patch 2: One sequencer, many phrases - Sequencer pitch out -> oscillator - IN 1 = basic step clock - IN 2 = syncopated trigger pattern - IN 3 = fill trigger pattern - OUT = envelope trigger or sequencer advance - MODE = switch mode ### What happens The same note sequence gets rephrased in multiple ways, which sounds like variations on a melodic theme. --- ## Patch 3: Density-controlled arpeggio generator - Arpeggiator/sequencer pitch -> oscillator - IN 1 = quarter-note trigger - IN 2 = eighth-note trigger - IN 3 = ratchet/accent trigger - MODE = sum mode - SEL CV = envelope, slider, or sequencer row - OUT = envelope trigger ### What happens As selection rises, the arpeggio becomes denser and more energetic, ideal for builds and transitions. --- ## Bottom line The **2hp 3:1** is best used for melody as a **trigger architecture tool**: - it selects between rhythmic sources, - combines them for note density, - converts gates to short triggers in sum mode, - and allows CV-controlled phrase changes. By itself it doesn’t generate notes, but in a melodic Eurorack patch it can be central to: - note timing, - phrase switching, - melodic density, - variation, - and live performance control. If you want, I can also turn this into: 1. a **beginner-friendly patch guide**, 2. a **generative melody patch recipe list**, or 3. a **“how to use with common module types” compatibility guide**. --- [Generated With Eurorack Processor](https://github.com/nstarke/eurorack-processor)