# ADDAC Systems — ADDAC-506 SignalFlow - [Manual PDF](../../manuals/ADDAC506_SignalFlow.pdf) --- [Manual PDF](attachment) # ADDAC506 VC Stochastic Function Generator & Expansion How to use it for **melodic** patching The ADDAC506 is primarily a **4-channel stochastic envelope / function generator**, not a dedicated oscillator or sequencer. But in Eurorack, that still makes it very useful for melody because it can generate: - evolving control voltages - stepped or re-randomized timing relationships - phrase contours - trigger structures - layered modulation for pitch, timbre, and articulation The attached pages describe the **main module plus expansion**, with these important functions: - **4 independent envelope channels** - **Randomized rise and fall times** between user-set min/max ranges - **CV control** over all rise/fall min/max settings - **Loop / One-shot** - **Slew / Trigger** behavior - **Amplitude** control: approximately **-10V to +10V** - **Offset** control: approximately **-10V to +10V** - **Envelope curve** from **linear to logarithmic/exponential** - **Gate out** during rise - **EOR** (end of rise) and **EOF** (end of fall) outputs - **Average Mix Out** - **Summing Mix Out** - Expansion: - **Random trigger inputs** to force new randomization mid-cycle - **Random CV outputs** reflecting the random value used for rise or fall time ## What this means musically This module does **not directly output quantized pitch sequences**. Instead, it creates **animated control voltages** that can become melodic when sent to: - a **VCO 1V/oct input** through an attenuator/quantizer - a **quantizer** - a **sample & hold** - a **sequential switch** - a **wavefolder/filter/resonator** to create pitch-like timbral melodies - logic or clocking utilities for phrase generation In practice, the ADDAC506 is best thought of as a **melody-shaping source**, not a conventional note sequencer. --- # Core melodic use cases ## 1. Use one channel as a pitch contour source Patch: - **ADDAC506 channel output** → **quantizer input** - **quantizer output** → **VCO 1V/oct** - Trigger the channel with gates or put it in **loop** - Adjust: - **Rise Min/Max** - **Fall Min/Max** - **Amplitude** - **Offset** - **Curve** ### Result The envelope becomes a continuously changing melodic contour. Once quantized, the slopes turn into note motion. ### Tips - Use **small amplitude** for narrow melodic ranges. - Use **offset** to place the melody into a useful register. - If **Rise Min > Rise Max** or similarly for Fall, the manual says it behaves as a **fixed** time control. That’s useful when you want one side stable and the other stochastic. - **Log/exp curves** can bias the melody toward lingering around some notes and moving faster through others. --- ## 2. Create 4 interrelated melodic lanes Since there are **4 independent channels**, you can build: - 4 voices - 4 modulation lanes for one voice - 3 voices plus one master phrase modulator Patch idea: - **Output 1** → quantizer → VCO A pitch - **Output 2** → quantizer → VCO B pitch - **Output 3** → filter cutoff or wavefolder depth - **Output 4** → VCA CV or FM amount ### Why it works Even if each channel is independent, they share the same panel logic and can be set to similar or contrasting timing regions. That gives a family resemblance between voices, which often feels more musical than fully unrelated random sources. --- ## 3. Use EOR and EOF to make melodic cascades The manual states: - **EOR** outputs when rise ends - **EOF** outputs when fall ends - **Gate out** is high during rise This makes the 506 very strong for **event chaining**. Patch: - **Channel 1 EOR** → trigger **Channel 2** - **Channel 2 EOF** → trigger **Channel 3** - **Channel 3 EOR** → trigger a **sample & hold** - S&H output → quantizer → VCO pitch ### Result You get a phrase where melodic note changes happen at structurally meaningful points in the envelopes rather than on a strict clock. This is excellent for: - generative melodies - rubato phrases - pseudo-counterpoint - self-evolving note timing --- ## 4. Use the expansion Random CV outputs as melodic sources The expansion provides: - **Random trigger inputs** for re-randomizing rise/fall values - **Random CV outputs** that expose the CV value used for rise/fall randomization - jumper selection between **rise random** or **fall random** This is one of the most immediately melodic features. Patch: - **Random CV out** → quantizer → VCO 1V/oct - **Random Trigger In** receives clocks, gates, or irregular triggers ### Result Every randomization event can generate a new pitch-related voltage. Because that voltage is tied to the envelope timing calculation, your **note choices and note shape/timing become correlated**. That correlation is musically powerful: notes and articulation evolve together. ### Great use - Rise random CV controls **pitch** - Same channel envelope output controls **VCA** - The note and its articulation are linked This often sounds more intentional than using unrelated random sources. --- ## 5. Build melody from the Average Mix output The manual describes: - **Average Mix Out** = average CV from all 4 channels - **Summing Mix Out** = sum of all 4 outputs Patch: - **Average Mix Out** → quantizer → oscillator pitch ### Why use average instead of sum? Average tends to be: - smoother - more centered - less likely to jump wildly This is useful for: - singable melodic lines - slowly evolving lead lines - modal drifting phrases If each channel has different rise/fall ranges, the average output becomes a composite phrase made from several interacting gestural layers. --- ## 6. Use the Summing Mix output for wider melodic leaps Patch: - **Summing Mix Out** → attenuator → quantizer → VCO pitch ### Result The sum output is generally more energetic and volatile than the average. This is better for: - angular melodies - experimental atonal lines - dramatic interval jumps - chaotic arpeggio-like movement Because the module can output large voltages, attenuation before the quantizer is often very important. --- ## 7. Slew mode as melodic glide processor The manual says: - **Slew** works for CVs, gates, and triggers - It behaves somewhat like a **CV envelope follower** - **Trigger** mode generates one cycle per trigger In melodic systems, **Slew mode** can reshape incoming pitch or modulation CV. Patch: - external sequencer CV → **channel signal input** - channel set to **Slew** - channel output → quantizer or directly to VCO pitch ### Uses - smooth glides between sequenced notes - randomized portamento behavior if rise/fall min/max are spread - expressive pitch lag - converting stepped random into curved melodic movement A particularly nice patch: - sequencer CV → Slew channel - output → quantizer - quantizer → VCO This gives a melody that keeps the broad gesture of the original sequence but gains stochastic timing and contour. --- ## 8. Trigger mode for articulated note shapes In **Trigger** mode, each incoming trigger fires one envelope cycle. Patch: - clock or rhythm source → channel input - channel output → quantizer → VCO pitch - same trigger or gate out → envelope/VCA for audio articulation ### Result Each note can have a pitch trajectory over the duration of the triggered envelope. Depending on speed, this may sound like: - ornamentation - pitch bends - micro-phrases - plucked/struck melodic gestures This works especially well with: - LPGs - FM voices - resonators - pinged filters --- # Best ways to combine the main module and expansion for melody ## A. Correlated pitch + articulation patch Patch: - **Expansion Random Trigger In 1** ← rhythmic trigger pattern - **Random CV Out 1** → quantizer → oscillator pitch - **Envelope Out 1** → VCA CV - **Gate Out 1** → envelope trigger or logic clock ### Why it’s good Pitch changes happen when the rise/fall randomization changes, while the envelope controls note articulation. This creates phrases where timing, note choice, and dynamics feel related. --- ## B. One channel per melodic function A very effective 4-channel allocation: - **Channel 1**: main pitch contour - **Channel 2**: transposition amount - **Channel 3**: timbre movement - **Channel 4**: phrase-level amplitude or density Patch example: - Ch1 out → quantizer A input - Ch2 out → attenuator → add to Ch1 before quantizer, or transpose quantizer reference - Ch3 out → filter cutoff / fold / FM index - Ch4 out → VCA CV or clock probability modulation This creates melodies that breathe and transform rather than just changing notes. --- ## C. Self-generating canon / round Patch: - Ch1 **EOF** → trigger Ch2 - Ch2 **EOF** → trigger Ch3 - Ch3 **EOF** → trigger Ch4 - Ch4 **EOF** → trigger Ch1 Then: - all 4 outputs → 4 quantizer channels → 4 oscillators or - all 4 outputs mixed/selected into one pitch path ### Result A rotating network of envelopes, each with randomized rise/fall times, creates staggered melodic entries and evolving relationships. Very good for ambient, minimalism, and generative counterpoint. --- ## D. Random CV outputs as hidden sequencer The expansion’s Random CV outputs can function like a strange sequencer lane. Patch: - **Random CV Out 1–4** → precision adder mixer or sequential switch - output → quantizer → VCO pitch - trigger the random inputs with related but not identical clocks ### Result You effectively get four stochastic pitch sources whose update timing is independently controllable. This can produce: - non-repeating melodies - polymetric note changes - phrase memory-like behavior if clocks are slow --- # Practical melodic patch recipes ## Patch 1: Generative lead voice You need: - ADDAC506 + expansion - quantizer - VCO - VCA - envelope or LPG - trigger source Patch: - Random trigger source → **Expansion Random In 1** - **Random CV Out 1** → quantizer → VCO 1V/oct - **Output 1** → VCA CV or filter CV - **Gate Out 1** → trigger envelope/LPG - Audio voice → VCA → output Set: - medium speed - trigger mode - moderate rise/fall ranges - small pitch range via quantizer/attenuation Result: A coherent generative melody where note selection and envelope behavior are connected. --- ## Patch 2: Melodic drone with internal movement Patch: - **Average Mix Out** → attenuator → quantizer → oscillator pitch - **Output 1** → filter cutoff - **Output 2** → wavefolder amount - **Output 3** → FM index - **Output 4** → stereo movement or reverb send CV Set channels to loop with different random ranges. Result: A slowly shifting drone with a pitch center that continuously evolves. --- ## Patch 3: Pseudo-arpeggiator Patch: - master clock → trigger Ch1 - Ch1 EOR → trigger Ch2 - Ch2 EOR → trigger Ch3 - Ch3 EOR → trigger Ch4 - Ch1–4 outputs → sequential switch CV inputs or mixer - switched/mixed result → quantizer → VCO Result: A chain of linked contour events that acts like an arpeggiator, but with variable note lengths and spacing. --- ## Patch 4: Humanized melody processor Patch: - external sequencer pitch CV → channel input in **Slew** mode - channel output → quantizer → VCO pitch - expansion random trigger input receives sparse accents Result: Your normal melody becomes organic and slightly unpredictable, with changing glide/response behavior. --- # Important musical behaviors from the manual ## Randomization happens at cycle start The manual specifically says the rise/fall randomization occurs **at the start of a cycle**. If you move controls during the cycle, changes are not applied until the next trigger/loop. ### Musical implication This makes phrase behavior stable within each note/event, which is good for melody. You don’t get erratic mid-note parameter changes unless you use the **expansion random trigger input**. --- ## Expansion random trigger can change timing mid-cycle The expansion allows re-triggering the randomization **at any point in time**. ### Musical implication This is ideal for: - accents - fills - phrase mutations - occasional surprise notes or bends Use a separate rhythm source to inject this only on selected beats. --- ## Lock / Unlock supports focused channel editing The manual says lock holds each channel’s rise/fall settings and prevents changes, making it easier to treat channels independently. ### Musical implication You can tune one channel as a stable melodic voice while letting others remain volatile. --- ## Amplitude and offset are crucial Because the envelope amplitude can span approximately **-10V to +10V**, and offset also shifts overall voltage, the raw output range is too large for direct melodic use in many patches. ### Recommendation For pitch work, use: - attenuator - offset utility - quantizer - precision adder This module becomes much more musically controllable when scaled carefully. --- # Strengths for melodic composition ## What it excels at - generative melody - correlated pitch and articulation - phrase evolution - non-grid timing - expressive CV contours - ensemble-like multi-voice motion - slow shifting tonal structures ## What it is not ideal for by itself - exact step sequencing - repeatable tonal basslines - strict 16-step melodies - direct scale-locked pitch output without a quantizer --- # Best companion modules To get the most melodic value from the ADDAC506, pair it with: - **Quantizer** Essential if you want tonal melodies. - **Precision adder / CV mixer** For transposition and combining multiple channels. - **Sequential switch** Great for turning the four channels into ordered melodic events. - **Sample & Hold / Track & Hold** Useful for extracting stable note values from moving envelopes. - **Clock divider / logic** To create interdependent phrase timing from EOR/EOF/Gate signals. - **Oscillator with good FM/timbre response** The module is excellent not just for pitch but also for melodic timbral animation. - **Attenuators / offsets** Very important due to the voltage range. --- # Bottom line The ADDAC506 and its expansion are best used for melody as a **stochastic phrase generator** rather than a classic sequencer. The most powerful melodic strategies are: 1. **Quantize the envelope outputs** 2. **Use the expansion Random CV outputs for pitch** 3. **Use EOR/EOF/Gate outputs to chain events** 4. **Use Average and Summing outputs for higher-level phrase contours** 5. **Correlate pitch, articulation, and timbre using the same channel** If you patch it with a quantizer and a few utility modules, it can produce melodies that feel: - organic - self-evolving - structurally coherent - less repetitive than ordinary step sequencing [Generated With Eurorack Processor](https://github.com/nstarke/eurorack-processor)