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:

What makes the NO-B 250's duophonic architecture unique is how the two voices interact:

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:

  1. Find the small ON/OFF switch in the top left and click it to the "ON" position. The interface will light up.
  2. 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).
  3. 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 & 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

Note on Sharing: The previous share-by-URL feature has been removed. To move sounds between devices or collaborators, use the SAVE button to export a preset file and send that file directly.

Special Presets

RECORD AUDIO

The RECORD AUDIO button allows you to record your performance directly to a high-quality .wav audio file.

  1. Press the RECORD AUDIO button to begin. The button's text will turn red and change to a STOP button with a running timer.
  2. Perform your piece on the synthesizer.
  3. 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:

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:

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.

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

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.

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

Oscillator Waveforms

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:

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

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

  1. 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.
  2. 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.
  3. 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:

  1. Enable the ARP switch and turn on HOLD (SWEEP mode is on by default).
  2. Spin the left knob to C4 (watch the note display)
  3. Quick-tap SPACE to add C4 to the sequence
  4. Press → several times until the display shows G4
  5. Quick-tap SPACE to add G4
  6. Press → until you reach E5 (this requires spinning past C5 and into the next octave)
  7. Quick-tap SPACE to add E5
  8. Press ← to go back down to C5
  9. 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.

Global ARP Controls

This section affects both arpeggiators when they are active.

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.

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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:

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:

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:

Row 3: Effects (Part 1)

Row 4: Effects (Part 2) & Global Controls

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:

Use Cases

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

  1. Enter LFO Mode.
  2. Click the LFO DEST knob you want to use (e.g., LFO 1 DEST). It will start blinking.
  3. 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:

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

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.

Understanding LFO Waveforms

The WAVE knob selects one of six different LFO shapes, each creating a different modulation character:

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:

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.

Keep it musical: Syncing lets LFO moves breathe with the arpeggiator instead of fighting it. Flip SYNC off when you want free-running modulation, then flip it back on to snap back to the grid.

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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

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

  1. Enable the Arpeggiator: Turn on the ARP switch for one of the oscillators.
  2. 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.
  3. Enable HOLD: Turn on the HOLD switch. This makes the arpeggiator keep playing continuously.
  4. 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.
  5. 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.
  6. 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:

Taking It Further

This technique becomes even more powerful when combined with other modulations:

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. Steps Mode (Dual Step Sequencers)

The STEPS switch sits below the LFO and DRUM toggles. Turning it on hides the main oscillator circles and reveals two 16-step octave sequencers (SEQ A and SEQ B) plus shared START/STOP controls inspired by the dual-row layout of Doepfer's Dark Time.

Programming Steps

Timing & Transport

Duo Mode (Per-Sequence Dual Slot)

Chain Mode (Transposition & Loop Slots)

Step Parameter Knobs

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9. Break / Drums Loops

A dedicated DRUMS switch sits just beneath the LFO controls. Turn it on to reveal the break-loop grid, where you can trigger curated drum breaks that lock to your arpeggiators.

Loop Controls

FX Blend

The FX knob now acts as a dry/wet send for the break loops. Turn it up to feed more of the drums into the synth's main chorus, distortion, delay, and reverb while retaining the dry signal underneath for punch.

Sync & Eligibility

Breaks follow the same sixteenth-note quantization grid as the arpeggiators. When you press PLAY, the loop queues until the next grid tick so the downbeat never lands early or late. A running arp is required to start playback so the drums know which tempo to follow.

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10. 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.

MIDI Learn & Custom Mapping

Once MIDI is connected, the selector row appears with MIDI IN/MIDI OUT dropdowns plus MIDI LEARN and CLEAR MIDI MAP buttons.

How It Works

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:

Enabling MIDI Clock

To enable MIDI Clock Out:

  1. Click the CONNECT MIDI button and select your MIDI output device
  2. Enable the MIDI Clock Out option (if available in your interface)
  3. Start an arpeggiator - the clock will sync to the arpeggiator's tempo
  4. 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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11. Duplicate Note Mode

Beyond the standard controls lies a hidden "Duplicate Note Mode," designed for creating highly complex and rhythmic arpeggio sequences.

Whispered secret: There's a hidden soundfont loader buried in the instrument. If you dime both DISTORTION and AM, you'll find the doorway.

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12. 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

DEDICATED CONTROLS

The below knobs are controlled with a global SHIFT attenuator:

Oscillator Controls

ARP Controls

GLOBAL EFFECTS (ROW 1)

GLOBAL EFFECTS (ROW 2)

GLOBAL EFFECTS (ROW 3)

GLOBAL EFFECTS (ROW 4)

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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!