NO-B 250 User Manual
The NO-B 250 is a web-based synthesizer designed for hands-on, immediate music creation. This guide will walk you through everything from making your first sound to understanding its most advanced features.
Understanding the Architecture: Duophonic Design
The NO-B 250 is a duophonic synthesizer, meaning it can play two notes simultaneously - one voice per oscillator. This makes it different from:
- Monophonic synths: Which can only play one note at a time
- Polyphonic synths: Which can play many notes at once (chords, complex harmonies)
What makes the NO-B 250's duophonic architecture unique is how the two voices interact:
- Independent: Each voice has its own filter, resonance, volume, and can run its own independent arpeggiator with unique sequences
- Shared: Both voices share the same global effects (Chorus, Distortion, Delay, Reverb) and the same ADSR envelope, giving the instrument a cohesive sonic character
This design allows you to create rich textures with interweaving melodies, polyrhythmic patterns, and harmonized sequences while maintaining the focused, intentional sound design of a performance instrument.
Index
1. Getting Started: Making Sound
Follow these simple steps to start playing:
- Find the small ON/OFF switch in the top left and click it to the "ON" position. The interface will light up.
- Important for Mobile Users: Make sure your device is NOT in "Silent Mode." Use the physical switch on your phone if necessary. If you change apps while playing the NO-B 250, you can tap anywhere to wake the audio engine back on to resume where you left off (arps will come back).
- Touch and hold one of the two large circles (the main knobs). You should hear a sound. Move your finger around the circle to change the note if you are on a mobile device, or drag the circle if you are on a computer.
Note: The NO-B 250 initializes with the Hero Preset called DREAMY MALLET (found in the KEYS category) - a carefully designed starting patch that showcases the instrument's capabilities. This preset features musical settings across the Scale, Key, and various Effects while keeping core Volume and Envelope settings dialed in, ensuring you always start with an inspiring and usable sound.
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2. System Controls (Presets, Sharing & Recording)
PRESETS & NAVIGATION
The preset system is now streamlined for instant access. The preset window is perpetually displayed, showing your current patch and providing quick navigation controls.
Preset Categories
The synthesizer includes category buttons for KEYS, BASS, PADS, LEADS, ARPS, RANDOM, and FX. Tap a category to see its presets in the drop-down menu.
Quick Navigation
Use the ← → arrow buttons next to the preset display to quickly browse through presets in the current category. This allows you to audition sounds rapidly without opening dropdown menus.
Navigation Scope: The arrow buttons navigate through the musical preset categories only:
KEYS,
BASS,
LEADS,
PADS, and
ARPS. The
RANDOM,
FX, and
INIT categories are excluded from quick navigation since they serve specialized purposes. This design makes it easy to browse through performance-ready sounds while preserving quick access to the INIT patch for building sounds from scratch. For a powerful auditioning workflow, see the
FURNACE Technique in the ARP Lock section.
Saving & Loading
- SAVE: Saves the synthesizer's current state to a .json file. Your browser will prompt you to download this file, which will be automatically named with the prefix "N-OB" and the current date for easy organization.
- LOAD: Allows you to load a
.json preset file that you previously saved. If the loaded preset has an arpeggiator with its HOLD switch enabled, it will begin playing immediately.
Special Presets
- INIT Patch: A clean slate preset with neutral settings (chromatic scale, minimal effects, basic envelope), perfect for building sounds from scratch. This is your blank canvas for sound design.
- RANDOM ARP: Generates a musically intelligent random arpeggio following compositional rules to prevent sonic chaos.
- RANDOM SOUND: Creates a randomized sound with varied effects and parameters while keeping essential controls musical.
SHARE FEATURE
The SHARE button allows you to instantly share your patches with others via a compressed URL. This powerful feature encodes the complete state of the synthesizer into a unique link.
What Gets Shared
When you click SHARE, the following elements are encoded into the URL:
- All knob positions (Oscillators, FX, ARPs, LFOs)
- Scale and Key settings
- Arpeggiator sequences and settings
- LFO patch cables and configurations
- Tempo mode (BPM vs MS)
- All switch states (ARP, HOLD, SYNC, etc.)
How to Use
- Create your patch - dial in sounds, build sequences, patch LFOs
- Click the SHARE button in the main header
- A compressed URL will be generated and copied to your clipboard
- Share this URL with others via text, email, or social media
- When someone opens the link, the NO-B 250 will load with your exact patch
Collaboration Tip: Share your most interesting patches in online communities, music forums, or with collaborators. The URL is much more convenient than downloading and sending JSON files, and it ensures anyone can instantly hear your creation in their browser.
RECORD AUDIO
The RECORD AUDIO button allows you to record your performance directly to a high-quality .wav audio file.
- Press the RECORD AUDIO button to begin. The button's text will turn red and change to a STOP button with a running timer.
- Perform your piece on the synthesizer.
- When you are finished, press the red STOP button. Your browser will automatically prompt you to save the recording.
RECORD MIDI
The RECORD MIDI button records the musical notes you play, not the sound itself. This is perfect for exporting your performance to other music software like Ableton or Logic Pro for further editing, arranging, and to hear the midi with different sounds.
Intelligent Track Exporting
The MIDI file is structured to match your performance:
- If you only record notes on one oscillator, your DAW will import it as a single MIDI track.
- If you record notes on both oscillators, it will import as two separate tracks, separating the parts for the left and right knobs.
Dynamic Tempo Exporting
The synthesizer will automatically detect your arpeggiator's speed and embed it into the MIDI file as a BPM. This is how it works:
- When an Arpeggiator is Active: If you are recording a single arpeggiator (or two arpeggiators with RATE SYNC enabled), the exported MIDI file's tempo will be calculated to match the arpeggiator's speed. This allows the performance to snap perfectly to the grid in your DAW. The available tempo range is from 20 BPM to 300 BPM.
- When No Arpeggiator is Active: If you are playing freely without an arpeggiator, or with two unsynced arpeggiators, the MIDI file will default to a standard 120 BPM.
Pro-Tip for Clean Recordings: The MIDI file is generated with a single tempo based on the arpeggiator's rate at the moment you stop recording. For the cleanest, most grid-aligned results, it is best to set your desired tempo with the RATE knob before you start recording and avoid changing it during the take.
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3. Scale and Key Controls
These two dropdown menus are the musical brain of the synth, ensuring everything sounds harmonious.
- Key Selector: The first dropdown sets the root note, or "key," of your song (e.g., C, F#, A).
- Scale Selector: The second dropdown selects the musical scale that will be built on that root note. You can choose from common scales like Major and Minor, modes like Dorian and Phrygian, or even pentatonic scales.
Defining a Custom Scale
The true power of the scale system is unlocked when you select CUSTOM from the scale dropdown. A small piano keyboard will appear, allowing you to design your very own scale from scratch by clicking on the keys you want to include.
Instead of selecting a full 7-note scale, try selecting only three notes that form a chord, like C, E, and G (a C Major triad). Now, the main knobs and any arpeggio you create will be constrained to only those three notes, playing them across different octaves. This is a powerful way to create rhythmic, chordal patterns that always sound perfectly in harmony.
Note: Your custom scale is preserved even when you switch to a different scale preset. When you return to CUSTOM, your previously designed scale will still be there, allowing you to quickly toggle between different harmonic palettes.
Live Scale & Key Switching
You can change the Key and Scale while an arpeggio is playing. The synthesizer will intelligently nudge each note in your sequence to the closest possible note in the new scale, allowing you to create dynamic and musical chord progressions on the fly.
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4. The Oscillator Sections (The Big Knobs)
These are the heart of the synth. Each of the two main knobs controls a sound source, often called an oscillator. These knobs control the pitch of the note. The notes are "quantized" to the selected Key and Scale, so you can't play a "wrong" note. Spinning the knob moves through the notes of the scale, and turning it a full 360 degrees moves you up an octave.
How to Play the Knobs
-
On a Computer: Click and hold a knob, then drag your mouse to spin it and change the note. You can also use the
SPACE bar for the left knob and the B key for the right knob. While the note is sounding, you can change the pitch using:
- Left Knob Spin Keys:
←/→ for fast spinning and ↑/↓ for slow spinning
- Right Knob Spin Keys:
,/. for fast spinning and ;/' for slow spinning
- Arrow Buttons: Click the small
< and > buttons below each knob
-
On a Mobile Device: Touch and hold a knob, then move your finger to spin it and hear the notes change. While the note is sounding, you can also use the small
< and > buttons below each knob to spin the knob, changing its pitch (> spins the knob clockwise for higher pitches and < spins it counter-clockwise for lower pitches).
Silent Note Selection (Spinning Without Playing)
Sometimes you want to change the note of a knob before you play it. This allows you to cue up your next note silently. This is the essential technique for building complex arpeggios with wide intervallic leaps.
- On a Computer: You have multiple options for silent spinning:
- Use the keyboard's arrow keys (
← → for fast spinning, ↑ ↓ for slow spinning on Knob 1)
- Use the dedicated spin keys (
, . for fast, ; ' for slow on Knob 2)
- Click the small
< and > arrow buttons located directly beneath each main knob
- On a Mobile Device: Tap the small
< and > buttons located directly beneath each main knob to spin it silently.
As you spin the knob silently, watch the note display (e.g., 'G3') underneath. It will update in real-time, showing you exactly which note is ready to be played next.
Why This is Important
Besides pre-selecting a starting note, this technique is essential for building creative arpeggios. When creating a sequence with the HOLD and SWEEP MODE functions active (see Core ARP Controls), this is the primary way to add notes that are not directly next to each other in the scale, allowing for wide melodic leaps in your patterns.
Oscillator Controls
- FILTER: This is like a tone knob. At its lowest setting, it cuts out high frequencies, making the sound darker and more muffled. At its highest setting, it allows all frequencies through, making the sound brighter.
- RES (Resonance): This knob boosts the frequencies right at the FILTER's cutoff point, creating a "whistling" or "peaking" sound.
- VOLUME: Controls the individual volume level for that oscillator.
Each oscillator can produce four different waveforms, giving you a wide palette of timbres to work with. The waveform buttons are located above each oscillator knob:
- SAW: The brightest waveform with the fullest harmonic content. Sounds bold and brassy - the foundation of classic analog synth sounds. Perfect for cutting leads, fat bass, and lush pads.
- SQUARE: Rich in odd harmonics, creating a hollow, clarinet-like timbre. Excellent for punchy bass, aggressive leads, and classic chip-tune sounds.
- SINE: A pure, smooth tone with no harmonics - perfect for sub-bass, mellow pads, or flute-like sounds. The gentlest waveform.
- TRIANGLE: Slightly brighter than sine with gentle odd harmonics - creates a hollow, woody character. Great for retro basslines and softer lead sounds.
Layering Tip: Try using different waveforms on each oscillator for rich, complex timbres. For example, use a SAW wave on Oscillator 1 for brightness and a SINE wave on Oscillator 2 played an octave lower for warmth. You can also turn up OSC3 MIX to add sub-bass weight to both oscillators simultaneously, creating massive, full-bodied sounds.
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5. The Arpeggiator (ARP)
The NO-B 250's arpeggiator system is far more than a simple auto-chord player - it's a powerful hybrid of step sequencer and performance arpeggiator. Each of the two oscillators has its own independent arpeggiator, allowing you to create complex polyrhythmic patterns, layer interlocking melodies, or craft intricate sequences with precise control over every note. You can build custom melodic sequences with wide intervallic leaps, apply Euclidean rhythmic patterns, modulate sequences in real-time with LFOs, and visually edit your patterns with an interactive note grid. This dual-arpeggiator architecture transforms the synthesizer into a complete composition tool.
Core ARP Controls
- ARP Switch: The main power switch for the arpeggiator.
- MODE: Toggles between the default SWEEP (add multiple, different notes to the sequence) and NOTE REPEAT (repeats only the single note the knob is currently set to. With HOLD activated, the played note will change just by spinning the knob with no note play input needed, which is powerful when modulated with an LFO).
- HOLD: "Latches" the arpeggio, allowing it to play continuously even after you release a note.
- RATE: Controls the speed of the arpeggio.
- ↑↓ (Transpose): Shifts the entire sequence up or down within the selected scale. It has a range of -12 to +12 scale steps.
- OCTS: Adds up to three additional octaves to the pattern.
- FEEL: Applies different "Euclidean" rhythmic patterns to the sequence instead of a steady stream of notes. There are 9 patterns, from simple to complex. See Understanding FEEL for details.
Performance Tip: You can change the TRANSPOSE value in real-time while an arpeggio is playing. The sequence will immediately shift up or down within the scale, allowing you to perform melodic variations and build tension on the fly without stopping the pattern.
Building Complex Sequences with HOLD Mode
The real power of the arpeggiator emerges when you combine HOLD mode with silent note selection in SWEEP mode. This workflow allows you to construct intricate melodic patterns with precise control over every note.
The Two-Step Workflow
- Quick Tap to Add: Briefly press and release the SPACE or B key (or tap and release a knob on mobile). This adds the current note to the sequence without sustaining it.
- Scroll Silently: Use the arrow keys, dedicated spin keys, or < > buttons (available on both desktop and mobile) to move to your next desired note without making a sound.
- Repeat: Tap again to add that note, then scroll to the next position.
Practical Example: Building a Melodic Sequence
Let's say you're in the key of C Major and want to create the sequence: C4 - G4 - E5 - C5
On Desktop:
- Enable the ARP switch and turn on HOLD (SWEEP mode is on by default).
- Spin the left knob to C4 (watch the note display)
- Quick-tap SPACE to add C4 to the sequence
- Press
→ several times until the display shows G4
- Quick-tap SPACE to add G4
- Press
→ until you reach E5 (this requires spinning past C5 and into the next octave)
- Quick-tap SPACE to add E5
- Press
← to go back down to C5
- Quick-tap SPACE to add C5
The arpeggiator is now playing your custom four-note pattern. You can continue adding notes, delete unwanted ones by double-clicking the colored blocks, or mute notes by single-clicking them (see The Visual Sequence Editor).
On Mobile:
The process is identical, but you'll tap the large knob briefly instead of pressing SPACE or B, and use the < > buttons to scroll silently between notes. (Note: The < > buttons are also available on desktop, providing an alternative to keyboard shortcuts.)
The Visual Sequence Editor
When an arpeggio is active, a row of colored blocks appears and will remain when the HOLD switch is active, providing a clear visual representation of your sequence. This display is interactive and allows for powerful real-time editing.
Each note in the sequence is represented by a colored block. The color corresponds to the note's pitch, different notes have different colors, making it easy to visually identify your melody at a glance. When the arpeggio is actively playing, one block will be brighter than the others, showing you exactly which note is currently sounding. For mobile users, pinch-zooming can aid with accurate touch muting/deletion of the small note blocks.
- To Mute/Unmute a Note: Single-click (or single-tap) a note block. It will turn grey, and the arpeggiator will treat it as a rest, preserving the overall rhythm of the sequence. Click it again to reactivate it.
- To Delete a Note: Double-click (or double-tap) a note block to permanently remove it from the sequence.
Global ARP Controls
This section affects both arpeggiators when they are active.
- RATE SYNC: When ON, the RATE knobs of both arpeggiators are linked together, keeping them perfectly synchronized. RATE SYNC automatically enables when you turn on the second arpeggiator - if Arp 1 is running at 166 BPM and you enable Arp 2, it will immediately match that tempo and RATE SYNC will turn on. From that point forward, adjusting either ARP's RATE knob will move both in lockstep. You can disable RATE SYNC if you want to create polyrhythmic patterns with independent tempos.
- ORDER: Changes the playback order of notes (Up, Down, Up/Down, Random, or AS PLAYED).
- AS PLAYED - The Sequencer Mode: This is where the arpeggiator becomes a true step sequencer. Instead of reorganizing your notes by pitch, AS PLAYED respects the exact order in which you added them. This unlocks the ability to create dramatic melodic leaps and intentional note patterns. For example, using silent scrolling, you could build a sequence like C6 → C2 → G5 → C2 → E3 - wide intervallic jumps that would be impossible with the other playback modes. The arpeggiator becomes less of an automatic chord player and more of a compositional tool, allowing you to craft precise, dynamic melodies with complete control over the note order.
Advanced: The Tempo System (BPM vs MS Mode)
The NO-B 250 features a sophisticated dual-mode tempo system that fundamentally changes how the arpeggiators behave. Understanding these modes unlocks new possibilities for both tight, musical synchronization and experimental, fluid timing.
The Two Tempo Modes
The synthesizer operates in one of two modes at any given time:
- BPM Mode (Beats Per Minute): The default. Arpeggiators are locked to a musical grid, measured in traditional tempo units (5-300 BPM). Perfect for creating rhythmically tight, synchronized patterns.
- MS Mode (Milliseconds): A more experimental mode where tempo is measured in raw time intervals (10-2000ms). Ideal for polyrhythmic exploration, granular-speed textures, and subtle tempo drift effects.
Switching Between Modes
To toggle between BPM and MS mode, double-click (or double-tap on mobile) either RATE knob while an arpeggiator is active. The tempo display will immediately switch formats:
- BPM Mode Display: Shows as
120 BPM
- MS Mode Display: Shows as
125 MS
Performance Tip: The mode switch is global - changing the mode for one arpeggiator changes it for both. However, each arp maintains its own tempo value, so switching modes won't cause a sudden speed change.
How BPM Mode Works: The Master Clock
Both tempo modes use the same internal master clock - a high-precision timing system that polls every 2 milliseconds. The difference is how that clock is used.
In BPM mode, the clock provides several key benefits:
- Perfect Quantization: The arpeggiator checks each tick against a global quantization grid, ensuring notes snap to the musical timing. When you start an arpeggio or enable RATE SYNC, notes are automatically quantized to the next 16th note, preventing arpeggios from starting "off the beat."
- Drift Resistance: If your browser tab loses focus or CPU resources, the master clock self-corrects by skipping ahead rather than accumulating timing errors. Your sequence stays locked to the grid.
- Musical Tempo Changes: When you adjust the RATE knob in BPM mode, the synthesizer preserves the arpeggio's rhythmic phase - where it is in the current beat cycle. This allows you to speed up or slow down without losing the groove.
Timing Your Second Arp: Quantization snaps notes to the next available 16th-note slot on the grid (1-e-&-a-2-e-&-a...), not necessarily to the downbeat. If Arp 1 is playing on the "1" and you trigger Arp 2 slightly late, it will snap to the "e" slot and stay offset. For perfect downbeat alignment between two arps, trigger the second arp slightly early - the quantization will catch it and snap it to the next "1". This gives you tight, phase-locked patterns. If you want intentional rhythmic offset, trigger on the upbeats.
How MS Mode Works: Independent Timing
MS mode uses the same 2ms master clock polling, but with completely different logic. Instead of checking against a global grid, each arpeggiator asks: "Has enough time passed since my last note?" This creates independent timing for each sequence.
This mode is ideal for:
- Polyrhythmic Exploration: Set Arp 1 to 333ms and Arp 2 to 500ms to create interlocking, non-grid-based patterns that phase in and out of sync.
- Generative Drift: Because each arpeggiator tracks its own timing independently, slight imperfections in browser timing will cause the arpeggios to naturally drift apart over long durations, creating organic, evolving textures.
- Precise Millisecond Control: For sound design work, you may want an arpeggio to repeat at exactly 127ms or 873ms - intervals that don't map cleanly to musical tempos.
Technical Note: MS mode uses a non-linear curve for the RATE knob, allowing control from extremely fast to extremely slow. The range spans from 10ms (blazingly fast, granular-like textures) to 2000ms (very slow, 2 full seconds per note). At lower knob values (slower tempos), small movements result in large time changes for precise control. At higher knob values (faster tempos), the curve compresses to reach those extreme 10ms speeds.
RATE SYNC Behavior Across Modes
The RATE SYNC switch behaves differently depending on the active tempo mode:
- In BPM Mode: Both arpeggios lock to the master clock at the same tempo. They are perfectly synchronized and will always stay in phase, even if you modulate the rate with an LFO.
- In MS Mode: Both arpeggios set their target intervals to the same millisecond value, but because each tracks its own timing independently (rather than using a shared grid), they may drift slightly over time due to the nuances of checking local time deltas. This creates a "humanized" feel.
Tempo Mode and MIDI Export
When you record MIDI, the export process analyzes which tempo mode you were using:
- If in BPM Mode: The MIDI file's tempo is set to match the arpeggiator's BPM, ensuring your sequence aligns perfectly to the DAW's grid.
- If in MS Mode: The synthesizer calculates the equivalent BPM from the millisecond interval and exports that. For example, 500ms per 16th note translates to 120 BPM.
Phase Preservation During Tempo Changes
One of the most sophisticated features of the tempo system is phase preservation. When you adjust the RATE knob while an arpeggio is playing:
- BPM Mode: The synthesizer calculates how much time remains until the next note in the old tempo, then scales that remaining time proportionally to the new tempo. If you were 75% of the way to the next note at 100 BPM, you'll still be 75% of the way to the next note at 200 BPM.
- MS Mode: Uses the same proportional scaling, but based on elapsed milliseconds rather than musical beats.
This ensures that tempo changes feel musical rather than jarring - the rhythm morphs smoothly rather than suddenly jumping to a new position.
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The "FEEL" Knob: Euclidean Rhythms Explained
The FEEL knob uses Euclidean rhythms to create patterns. Think of it as spacing a certain number of "beats" as evenly as possible over 16 steps. However, when your arp sequence is a different length than the 16-step pattern (for example, you have a 7-note melody), the rhythmic pattern will shift on each repetition, creating interesting and unexpected polyrhythms that evolve over time. An "X" represents a note being played, and a "-" represents a silent step.
- Pattern 1:
X X X X X X X X X X X X X X X X (16 notes)
- Pattern 2:
X - X - X - X - X - X - X - X - (8 notes)
- Pattern 3:
X - - - X - - - X - - - X - - - (4 notes)
- Pattern 4:
X - - X - - X - X - - X - - X - (5 notes)
- Pattern 5:
X - - - - X - - - - X - - - - - (3 notes)
- Pattern 6:
X - X - X - X X - X - X - X - - (7 notes)
- Pattern 7:
X - X X - X - X X - X - X X - X (9 notes)
- Pattern 8:
X X - X X - X X - X X - X X - X (11 notes)
- Pattern 9:
X X X - X X X X - X X X X - X X (13 notes)
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ARP LOCK (Advanced Workflow Feature)
ARP Lock is a powerful workflow feature that preserves your arpeggio sequences when loading new presets. This allows you to write a melodic pattern once and then audition different sounds without losing your sequence.
How It Works
When ARP Lock is enabled (the switch is in the ON position), loading a preset will:
- Preserve your current arpeggio sequences on both oscillators
- Keep all ARP settings (RATE, TRANSPOSE, OCTS, FEEL, MODE, HOLD)
- Load only the sound design elements of the preset (oscillator settings, effects, envelopes)
Creative Workflow: Build a complex 16-step sequence using
HOLD and SWEEP mode, then enable ARP Lock and browse through the BASS, LEADS, or PADS categories. Your sequence will play with each new sound, letting you quickly find the perfect timbre for your pattern.
Overriding ARP Lock
When you load a preset from the ARPS category, it will override ARP Lock and load the preset's arpeggio settings. This ensures that arp-specific presets can still demonstrate their intended patterns.
Power Workflow - The FURNACE Technique: Here's a killer way to explore the synthesizer's sonic range: Load the FURNACE preset from the ARPS category, enable both ARP Lock and LFO Lock, then use the arrow buttons to cycle through the KEYS, BASS, LEADS, and PADS categories. You'll hear FURNACE's complex sequence and modulation pattern played with completely different timbres - it's like having a premade "test sequence" that reveals each preset's character instantly.
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6. Global Effects (The Small Knobs)
These knobs affect the overall sound coming from both oscillators. They are arranged in a 4x4 grid below the main oscillator sections.
Row 1: Envelope (ADSR)
The envelope shapes the volume of each note over time. These four controls work together to create the characteristic "shape" of a sound:
- ATTACK: How long it takes for the sound to reach full volume after you press a note (0.001s to 2s). Low values create punchy, percussive sounds like drums or plucked strings. High values create slow swells like a violin or pad.
- DECAY: After reaching full volume, how long it takes to drop to the sustain level (0.001s to 2s). Short decay creates plucky sounds; long decay creates evolving textures.
- SUSTAIN: The volume level the note holds at while you continue to hold it (0% to 100%). At 0%, notes behave like a piano - they fade away even if held. At 100%, notes stay at full volume.
- RELEASE: After you release a note, how long it takes to fade to silence (0.001s to 1.25s). Short release stops notes abruptly; long release creates smooth, overlapping transitions between notes.
Quick Start Presets: For a pluck, try: Attack: 0%, Decay: 30%, Sustain: 0%, Release: 20%. For a pad, try: Attack: 60%, Decay: 40%, Sustain: 80%, Release: 70%.
Row 2: Timbre & Tuning
These controls shape the character and richness of the sound:
- CHORUS: Widens and thickens the sound by creating subtle pitch and timing variations, simulating multiple voices playing at once. This emulates the classic Juno-106 chorus circuit. At low settings, it adds subtle depth. At high settings, it creates a lush, swirling stereo image.
- OSC3 MIX: Blends in a third oscillator tuned an octave below the main oscillators, adding weight and bass to your sound. This is particularly useful for creating sub-bass in electronic music or adding body to lead sounds.
- DETUNE: Slightly shifts the pitch of each oscillator's internal voices, creating a richer, more analog-sounding texture. At low settings, it adds subtle warmth; at high settings, it creates wide sounds.
- GLIDE: Causes notes to slide smoothly from one pitch to the next instead of jumping instantly. Creates portamento effects. Low values give subtle pitch bends; high values create dramatic, swooping transitions.
Row 3: Effects (Part 1)
- DISTORTION: Adds harmonic saturation and overdrive. For the first half of the knob's range (0-50%), a low-pass filter is applied to tame the high frequencies, creating warm, analog-style overdrive. As you turn the knob past the midpoint, the filter opens up and bit-crushing is introduced, adding aggressive digital distortion and lo-fi textures.
- AM (Amplitude Modulation): Modulates the volume at varying speeds. At low settings (0-30%), creates classic tremolo - a gentle pulsing of the volume. As you increase the knob past 30%, the modulation rate enters audio frequencies (up to 500 Hz), producing ring modulation - a metallic, bell-like timbre with inharmonic overtones. This is a powerful tool for creating everything from subtle movement to aggressive, robotic textures.
- DELAY: A rhythmic echo effect with stereo ping-pong behavior. This knob controls the wet/dry mix - how much delayed signal is blended with the original sound.
- DLY TIME: Sets the delay time from 10ms (slapback echo) to 1.5 seconds (long atmospheric echoes). The left and right channels use slightly different delay times (50% ratio) for a natural stereo effect. The delayed signal feeds back into itself at 60% for multiple repeats.
Row 4: Effects (Part 2) & Global Controls
- REVERB: Simulates acoustic spaces, from small rooms to large halls. Uses a Freeverb-style stereo algorithm with four comb filters per channel (eight total) and two allpass filters per channel for realistic spatial imaging. Add subtle amounts for natural space, or turn it up for ambient, atmospheric textures.
- RVB TIME: Controls how long the reverb tail lasts before fading to silence. Low values create tight, room-like spaces. High values create expansive, cathedral-like ambience. This knob adjusts the feedback in the reverb's comb filters (0.75 to 0.98).
- MASTER FILTER: A global low-pass filter that affects the entire mix after all other processing. Use it to darken the overall sound or create dramatic filter sweeps. At its lowest setting, it cuts everything above 40 Hz (extreme darkness). At its highest setting, it allows frequencies up to 22 kHz through (full brightness).
- MASTER VOLUME: The final output level control. Use this to balance the synthesizer with other instruments or prevent clipping. The internal signal path has headroom for hot signals, but this control ensures your final output is at an appropriate level.
Signal Flow: The audio is processed in the following order: Oscillators → Glide → Detune → OSC3 Mix → Envelopes (ADSR) → Saturation (soft clipper) → Individual Filters/Resonance → Individual Volumes → Stereo Panning → Chorus → Distortion → AM → Delay → Reverb → Master Filter → Master Volume. Understanding this signal chain helps you predict how effects will interact with each other.
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7. The LFOs (Low-Frequency Oscillators)
The LFOs are the secret to adding movement and life to your sounds. An LFO is an unheard, slow-moving oscillator used to automatically turn other knobs for you, creating effects like filter sweeps, vibrato, and rhythmic pulses. The NO-B 250 has four independent LFOs, each capable of modulating multiple parameters simultaneously through LFO chaining.
Entering LFO Mode
To access the LFO controls, click the small switch located just below the Global FX controls. The interface background will change color, and a new grid of LFO knobs will appear. This is the LFO patching view. The LFO controls are arranged in columns. Click the switch again to exit.
LFO LOCK
LFO Lock preserves your modulation routings when loading new presets. This is essential for maintaining complex modulation setups while exploring different sounds.
How It Works
When LFO Lock is enabled, loading a preset will:
- Preserve all LFO patch cable connections (which parameters each LFO is controlling)
- Keep all LFO settings (RATE, DEPTH, WAVE, SYNC state)
- Load the sound design elements of the preset while maintaining your modulation architecture
Use Cases
- Modulation Templates: Create a complex multi-LFO setup using chaining. For example: LFO 1 → OSC 1 Filter + OSC 2 Filter (chained for synchronized sweeps), LFO 2 → Delay + Reverb (chained for unified spatial movement), LFO 3 → LFO 1's Rate (meta-modulation), LFO 4 → Transpose. Enable LFO Lock and browse presets - your entire modulation architecture stays intact.
- Live Performance: Set up rhythmic filter sweeps and tremolo effects, lock them, then switch between bass and lead sounds without rebuilding your modulation each time.
- Sound Design: When designing generative sequences, lock your LFO-to-Oscillator routings and experiment with different timbres without disrupting the melodic movement.
Lock Interaction: ARP Lock and LFO Lock work independently and can both be enabled simultaneously. When loading a preset from the ARPS category, it will override both locks to ensure the arp preset demonstrates its intended behavior with the correct modulation.
LFO Controls & Visual Patching
Each LFO has a RATE, DEPTH, WAVE (shape), and DEST (destination) knob. The NO-B 250 supports LFO chaining, which transforms a simple single-destination LFO into an expansive modulation source that can control multiple parameters simultaneously. This allows you to create complex, cohesive movement across your entire patch with minimal setup - one LFO becomes a unifying rhythmic or evolutionary force that ties together filters, effects, and oscillators.
Patching an LFO
- Enter LFO Mode.
- Click the LFO DEST knob you want to use (e.g., LFO 1 DEST). It will start blinking.
- Click on any knob on the synthesizer. A colored "patch cable" will appear, connecting the LFO to that parameter. The blinking stops and the display above the DEST knob shows what you're controlling.
Chaining (Adding Multiple Destinations)
To make one LFO control multiple parameters, you have two options:
- Option A: Click the same LFO's DEST knob again (it will start blinking), then click another parameter to add it to the chain.
- Option B: Click any parameter that's already patched to that LFO (the colored cable destination). This reopens the patching mode, allowing you to click additional parameters.
Repeat either method to keep adding destinations. Multiple colored patch cables will appear, all originating from the same LFO.
Advanced: Multiple LFOs → One Parameter
You can also route multiple LFOs to the same parameter, creating unique composite waveforms. For example, send a slow SINE wave from LFO 1 and a fast TRIANGLE wave from LFO 2 to the same FILTER knob. The filter will now move with a complex, evolving pattern that neither LFO could create alone - the fast triangle rides on top of the slow sine, producing organic, unpredictable modulation that sounds less "robotic" than a single LFO.
Unpatching
- Remove one parameter: Double-click/tap any parameter in the chain to remove just that connection.
- Remove all connections: Double-click/tap the LFO DEST knob to disconnect all cables from that LFO.
Creative Chaining Examples: Chain LFO 1 to both OSC 1 FILTER and OSC 2 FILTER for synchronized filter sweeps across both voices. Chain an LFO to REVERB, DELAY, and CHORUS so all spatial effects evolve together, creating unified movement. For extreme modulation, chain an LFO to FILTER, RES, and DETUNE simultaneously - the sound will morph through drastically different timbres as all three parameters dance together in sync.
The WAVE knob selects one of six different LFO shapes, each creating a different modulation character:
- SINE: A smooth, rolling wave - perfect for natural-sounding vibrato or gentle filter sweeps.
- TRI (Triangle): A linear ramp up and down - creates even, predictable movement.
- SQUARE: An on/off toggle between two values - great for rhythmic, stepped effects or gating.
- SAW UP: A steady rise that suddenly drops - builds tension then releases.
- SAW DN (Saw Down): A sudden jump followed by a steady fall - the opposite of SAW UP.
- RANDOM (Sample & Hold): Jumps to unpredictable values - creates chaotic, generative modulation.
LFO Sync: Musical Time Division
A useful feature of the LFO system is the ability to sync an LFO's rate to the tempo of your arpeggiators. This transforms the LFO from running at raw Hz frequencies into musical subdivisions that stay perfectly in sync with your sequences.
How to Enable Sync
Below each LFO DEST knob, you'll find a small switch labeled SYNC. This switch is initially disabled (greyed out) and will only become active when certain conditions are met:
- Requirement: At least one arpeggiator must be active and running.
- Synced Mode: If both arpeggiators are running with RATE SYNC enabled, the LFOs will lock to their shared tempo.
- Single Arp Mode: If only one arpeggiator is running, the LFOs will lock to that arpeggiator's tempo.
Once the conditions are met, the SYNC switches will light up and become clickable. Click the switch for any LFO you want to sync to the musical grid.
Important: The SYNC switches will automatically disable and turn off if you stop all arpeggiators or disable RATE SYNC when both arps are running. This is because there's no longer a master tempo reference for the LFOs to lock to.
Practical Applications
Synchronized Filter Sweeps: Enable SYNC and set an LFO Rate to 1/4 and patch it to the FILTER knob. The filter will open and close once every two beats, creating a pulsing effect that's perfectly locked to your arpeggio.
Rhythmic AM: Patch an LFO with a SQUARE wave to AM, set the rate to 1/4, and you'll get rhythmic gating that stays in perfect sync with your sequence.
Generative Melodies in Time: Patch an LFO to a main oscillator knob in NOTE REPEAT mode with SYNC enabled. Set it to 1/8 with a RANDOM wave. The melody will change on every 4th note, but stay locked to the musical grid, creating generative patterns that feel rhythmically coherent rather than chaotic.
Polyrhythmic Modulation: Enable SYNC on two different LFOs and set them to different subdivisions (e.g., LFO 1 at 1 and LFO 2 at 1/2). Patch them to different parameters like DELAY and REVERB. The two effects will modulate at different musical rates, creating complex, interlocking rhythmic textures.
Switching Between Free and Synced Mode
When you enable SYNC, the synthesizer stores your previous free-running Hz value. When you disable SYNC, the LFO returns to that stored rate, allowing you to toggle between locked and free modulation without losing your settings.
Creative Experiment: Try this workflow:
- Start an arpeggio in BPM mode at 120 BPM
- Enter LFO mode and patch LFO 1 to the arpeggiator's FILTER knob
- Enable SYNC for LFO 1 and set the rate to
1 (quarter notes)
- Patch LFO 2 to the arpeggiator's TRANSPOSE knob
- Enable SYNC for LFO 2 and set the rate to
2 (half notes)
You now have a filter that pulses on every beat while the melody shifts up and down every two beats - creating a complex, evolving pattern that's still musically coherent because everything is locked to the tempo grid.
Sync and BPM vs MS Mode
SYNC works in both BPM and MS modes, but the behavior is slightly different:
- In BPM Mode: The LFO rate calculations are based on the master clock's tempo, ensuring sample-accurate synchronization across all synced LFOs and arpeggios.
- In MS Mode: The LFO rate is calculated from the millisecond interval of the active arpeggiator. Because MS mode uses independent timers, there may be very slight drift over long periods, which can actually create interesting "humanized" modulation.
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Advanced Modulation: LFOs Controlling LFOs
For advanced sound design, the NO-B 250 allows you to use one LFO to modulate the parameters of another. For example, you can patch LFO 2 to control the RATE of LFO 1. This would cause the speed of LFO 1's effect to ramp up and down over time, creating complex, evolving textures that are classic in modular synthesis. To do this, simply enter LFO mode, click the DEST knob for your source LFO (e.g., LFO 2 DEST), and then click one of the parameter knobs of another LFO (e.g., RATE 1).
Creative Patching: Modulating the Arpeggiator
You can assign an LFO to modulate the RATE, FEEL, OCTS, or TRANSPOSE (↑↓) of an arpeggio. For example, patching a random LFO to the ↑↓ knob can create a generative, ever-changing melody that never repeats exactly the same way.
Modulating the Main Oscillators
One of the most powerful and unique features of the NO-B 250 is the ability to patch an LFO directly to either of the two main oscillator knobs (the big circles). This opens up an entirely new realm of sound design possibilities.
How It Works
When you patch an LFO to a main oscillator knob, the LFO will automatically rotate the knob for you, causing the pitch to move up and down through the selected scale. The LFO's RATE controls how fast the knob spins, the DEPTH controls how far it rotates (the range of notes), and the WAVE shape determines the pattern of movement.
Practical Applications
- Vibrato & Pitch Bends: A slow SINE wave with low depth creates smooth, musical vibrato. Increase the depth for dramatic pitch bends.
- Melodic Sequences: A SAW UP or SAW DN wave creates ascending or descending scale runs.
- Rhythmic Arpeggios: A SQUARE wave with medium rate creates a rhythmic, two-note pulse.
- Generative Melodies: A RANDOM wave creates unpredictable, ever-changing note sequences.
Combining with the Arpeggiator
The true magic happens when you combine LFO-to-Oscillator modulation with the arpeggiator. This is where the synthesizer becomes a powerful generative music machine.
Creating Generative Sequences
By combining an LFO patched to a main oscillator with the arpeggiator in NOTE REPEAT mode and HOLD enabled, you can create self-playing, evolving sequences that never repeat the same way twice.
The Setup
- Enable the Arpeggiator: Turn on the ARP switch for one of the oscillators.
- Set to NOTE REPEAT Mode: Click the MODE switch so it's in the OFF position (not SWEEP). This makes the arpeggiator repeat whatever single note the knob is currently pointing to.
- Enable HOLD: Turn on the HOLD switch. This makes the arpeggiator keep playing continuously.
- Play a Note: Press SPACE (or B for the right oscillator) once to start the arpeggiator. You'll hear it repeating the current note at the rate you've set.
- Patch an LFO: Enter LFO Mode, click a DEST knob, then click on the main oscillator knob that's running the arpeggiator. You'll see a colored cable connect them.
- Adjust the LFO: Set the LFO's RATE (speed), DEPTH (how many notes it moves through), and WAVE (the pattern of movement).
What Happens
The LFO is now automatically spinning the oscillator knob for you. Because the arpeggiator is in NOTE REPEAT mode with HOLD on, every time the LFO moves the knob to a new position, the arpeggiator immediately starts playing that new note. The result is a sequence that evolves in real-time based on the LFO's settings.
Creative Experiments:
- Use a slow SINE wave for smooth, flowing melodies.
- Use a RANDOM wave for chaotic, generative patterns.
- Patch a second LFO to the first LFO's RATE or DEPTH to create evolving, unpredictable changes.
- Add multiple LFOs: One controlling the main knob, another controlling the arpeggiator's TRANSPOSE or FEEL for layered complexity.
- Use the FEEL knob to apply Euclidean rhythms to the generated sequence.
Taking It Further
This technique becomes even more powerful when combined with other modulations:
- Patch another LFO to the arpeggiator's RATE to make the sequence speed up and slow down.
- Patch an LFO to FILTER or REVERB for sonic evolution that matches the melodic changes.
- Use both oscillators, each with their own LFO and arpeggiator settings, for complex polyrhythmic textures.
- Switch to Duplicate Note Mode to allow the LFO to add repeated notes to a SWEEP mode arpeggio, creating rhythmic emphasis.
This is where the NO-B 250 transcends being just a synthesizer and becomes an instrument for generative composition. With careful patching, you can create living, breathing soundscapes that evolve organically over time.
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8. Connecting to External MIDI
The NO-B 250 can send MIDI notes to external hardware synthesizers or software DAWs like Ableton Live, Logic Pro, and FL Studio. This allows you to use its unique note-generation capabilities to control your other instruments.
To get started, click the CONNECT MIDI button at the bottom of the synthesizer. This will scan for available MIDI outputs on your system and populate the dropdown menu next to it.
How It Works
- MIDI Output Options: If you have a physical MIDI interface connected to your computer, it should appear in the list. On a Mac, you can also use the built-in IAC Driver to create a virtual MIDI bus for sending MIDI between applications without any extra hardware. For detailed instructions on setting this up, Ableton provides an excellent guide along with instructions for Windows: Setting up a virtual MIDI bus.
MIDI Clock Out
The NO-B 250 now includes an optional MIDI Clock Out feature, allowing you to sync external MIDI hardware and software to the synthesizer's tempo.
How MIDI Clock Works
When MIDI Clock Out is enabled:
- The synthesizer sends standard MIDI clock messages (24 pulses per quarter note) at the current tempo
- External devices can sync their sequencers, arpeggiators, and effects to the NO-B 250's master clock
- Works in both BPM and MS modes - the synthesizer calculates the appropriate clock rate
Enabling MIDI Clock
To enable MIDI Clock Out:
- Click the CONNECT MIDI button and select your MIDI output device
- Enable the MIDI Clock Out option (if available in your interface)
- Start an arpeggiator - the clock will sync to the arpeggiator's tempo
- Your external gear will now follow the NO-B 250's tempo
Important Note: MIDI Clock is sent when at least one arpeggiator is active. If both arpeggiators are running with RATE SYNC enabled, they share the same clock. If the arpeggiators are unsynced, the clock will follow whichever arpeggiator was started first.
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9. Duplicate Note Mode
Beyond the standard controls lies a hidden "Duplicate Note Mode," designed for creating highly complex and rhythmic arpeggio sequences.
- How to Unlock: To toggle this mode, simply click on the main 'NO-B 250' title at the top of the synthesizer. The background will change to a tan color to confirm you are in this mode. Click again to toggle off. Note: the background will be green when the LFO is active in duplicate note mode.
- What it Does: In normal mode, the arpeggiator will only allow one of every note (one C4, one G4, etc.). In Duplicate Note Mode, this restriction is lifted, allowing you to add the same note multiple times to a sequence.
- Before: A default arp might play a simple sequence like
C4 - G4 - F4.
- After: In Duplicate Note Mode, you can create a pattern like
C4 - C4 - C4 - G4 - F4 - F4.
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10. Keyboard Shortcuts (QWERTY Layout)
For desktop users, the keyboard provides powerful, hands-on control over every knob. The workflow is designed for performance:
CORE CONTROLS
- PLAY KNOB 1: Press SPACE
- PLAY KNOB 2: Press 'B'
- SPIN KNOB 1 (FAST): Hold ← / →
- SPIN KNOB 2 (FAST): Hold , / .
- SPIN KNOB 1 (SLOW): Hold ↑ / ↓
- SPIN KNOB 2 (SLOW): Hold ; / '
DEDICATED CONTROLS
The below knobs are controlled with a global SHIFT attenuator:
- Turn a Knob UP: Press and hold the corresponding key.
- Turn a Knob DOWN: While still holding the key, press and hold the SHIFT key. The knob will immediately reverse direction. You can release and press SHIFT again to toggle the direction as you hold the note key.
Oscillator Controls
- OSC 1 FILTER: 1
- OSC 2 FILTER: 4
- OSC 1 RES: 2
- OSC 2 RES: 5
- OSC 1 VOLUME: 3
- OSC 2 VOLUME: 6
ARP Controls
- ARP 1 RATE: -
- ARP 2 RATE: =
- ARP 1 TRANSPOSE: [
- ARP 2 TRANSPOSE: ]
- ARP 1 OCTAVES: O
- ARP 2 OCTAVES: P
- ARP 1 FEEL: K
- ARP 2 FEEL: L
GLOBAL EFFECTS (ROW 1)
- ATTACK: Q
- DECAY: W
- SUSTAIN: E
- RELEASE: R
GLOBAL EFFECTS (ROW 2)
- CHORUS: A
- OSC3 MIX: S
- DETUNE: D
- GLIDE: F
GLOBAL EFFECTS (ROW 3)
- DISTORTION: Z
- AM: X
- DELAY: C
- DLY TIME: V
GLOBAL EFFECTS (ROW 4)
- REVERB: T
- RVB TIME: Y
- MASTER FILTER: U
- MASTER VOLUME: I
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For any suggestions, bugs, or just to share something you've made, you can email me at jerome.potter at g m a i l . c o m. Enjoy!