🎚️ MOTU M4 - Complete Developer's Guide¶
Target Audience: AudioLab developers using MOTU M4 interface Purpose: Leverage M4's exceptional converters and metering for development Last Updated: 2025-10-03
📊 SPECS OVERVIEW¶
┌─────────────────────────────────────────────────────────────┐
│ MOTU M4 │
├─────────────────────────────────────────────────────────────┤
│ 🎤 Analog Inputs: 4× Combo XLR/TRS (Mic/Line) │
│ 2× on front (with preamps) │
│ 2× on rear (line-level only) │
│ 🔊 Analog Outputs: 4× TRS (2× Main + 2× Line Out) │
│ 1× Headphone (front, 1/4") │
│ 📡 Digital I/O: None (analog-focused design) │
│ 🎹 MIDI I/O: 1× MIDI In, 1× MIDI Out (5-pin DIN) │
│ ⚡ Sample Rates: 44.1, 48, 88.2, 96, 176.4, 192 kHz │
│ 🎯 Latency: 2.5ms RTL @ 48kHz/64 samples │
│ (Measured: exceptionally low) │
│ 🔌 Connectivity: USB-C (USB 2.0 protocol, bus-powered) │
│ 💻 Platforms: Windows 7+, macOS 10.11+, iOS │
│ 💰 Price: ~$250 USD (2025) │
│ 🏆 Class: Mid-tier professional interface │
│ │
│ ⭐ STANDOUT FEATURES: │
│ • ESS Sabre32 Ultra DAC (flagship chip, 120dB DNR) │
│ • LCD metering (RMS, peak, stereo correlation - onboard!) │
│ • Full-color LED level rings (visual feedback) │
│ • Ultra-low noise floor (-129dBu EIN) │
│ • Independent monitor/line outputs (flexible routing) │
│ • Loopback mode (built-in, for streaming/testing) │
└─────────────────────────────────────────────────────────────┘
🎯 WHY THIS INTERFACE FOR DEVELOPMENT¶
✅ ADVANTAGES¶
ESS Sabre32 Ultra Converters 🏆
The M4's secret weapon: Pro-grade DAC chip
┌──────────────────────────────────────────────────────────┐
│ ESS ES9026PRO DAC (same chip as in $3,000+ interfaces) │
│ │
│ Specs: │
│ • Dynamic Range: 120dB (A-weighted) │
│ • THD+N: -115dB (0.00018% - essentially unmeasurable) │
│ • Frequency Response: ±0.05dB (20Hz-20kHz) │
│ │
│ What this means for development: │
│ ✅ You hear EXACTLY what your plugin outputs │
│ ✅ No converter coloration masking issues │
│ ✅ Extremely low noise floor (hear subtle artifacts) │
│ ✅ Rivals interfaces 3-4× the price │
│ │
│ Comparison: │
│ • MOTU M4: ESS Sabre32 Ultra (120dB DNR) │
│ • Focusrite 4i4: Custom Focusrite (108dB DNR) │
│ • RME Babyface: AKM AK4490 (113dB DNR) │
│ • UA Apollo: UA custom (117dB DNR) │
│ │
│ Verdict: M4 has BEST converters for the price │
└──────────────────────────────────────────────────────────┘
LCD Metering Display 📊
Unique feature: Full metering on hardware (no software needed)
┌──────────────────────────────────────────────────────────┐
│ FRONT PANEL LCD SHOWS: │
│ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │
│ 📈 Input Levels (1-4): │
│ • Peak hold (catches transients) │
│ • RMS average (true loudness) │
│ • Numeric dBFS readout (precise) │
│ │
│ 📊 Output Levels: │
│ • Main L/R (monitors) │
│ • Line 3/4 (alternate outputs) │
│ │
│ 🎯 Stereo Correlation: │
│ • Phase meter (L/R relationship) │
│ • +1.0 = Mono (L=R identical) │
│ • 0.0 = Perfect stereo │
│ • -1.0 = Out of phase (DANGER!) │
│ │
│ Why this matters for development: │
│ ✅ Instant visual feedback (no need to open DAW meters)│
│ ✅ Catch clipping before it prints to recording │
│ ✅ Verify stereo width (does plugin maintain phase?) │
│ ✅ Work without computer screen (focused listening) │
└──────────────────────────────────────────────────────────┘
Full-Color LED Level Rings 🎨
Every knob has RGB LED ring (gain, monitor volume):
┌──────────────────────────────────────────────────────────┐
│ Color-Coded Level Indication: │
│ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │
│ 🟢 Green (-∞ to -18dB) Safe zone │
│ 🟡 Yellow (-18 to -6dB) Optimal recording level │
│ 🟠 Orange (-6 to -3dB) Getting loud │
│ 🔴 Red (-3 to 0dB) Danger (near clipping) │
│ ⚫ Off (0dB+) CLIPPING (bad!) │
│ │
│ Customizable: │
│ • MOTU M Series app: Adjust brightness (0-100%) │
│ • Threshold colors (change when yellow starts) │
│ • Meter ballistics (peak vs. RMS weighting) │
│ │
│ Developer benefit: │
│ • Peripheral vision monitoring (eyes on code, not meters)│
│ • Red ring = "something's wrong, check signal" │
│ • Fast gain-staging without looking at numbers │
└──────────────────────────────────────────────────────────┘
Exceptional Value 💰
Features found in $500-800 interfaces, for $250:
┌──────────────────────────────────────────────────────────┐
│ PRICE COMPARISON (Street prices, 2025): │
│ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │
│ MOTU M4: $250 120dB DNR, LCD meters │
│ Focusrite Scarlett: $230 108dB DNR, basic meters │
│ Audient iD4: $200 116dB DNR, no LCD │
│ SSL 2+: $280 110dB DNR, legacy EQ button │
│ RME Babyface Pro: $750 113dB DNR, TotalMix FX │
│ UA Apollo Twin: $900 117dB DNR, UAD DSP │
│ │
│ VERDICT: │
│ M4 has best converters + metering under $300 │
│ Only beaten by RME/UA (3-4× price) │
└──────────────────────────────────────────────────────────┘
MIDI I/O 🎹
Rare in modern USB interfaces (most dropped MIDI):
┌──────────────────────────────────────────────────────────┐
│ 5-pin DIN MIDI: │
│ • IN: Receive from hardware controllers/synths │
│ • OUT: Send to external gear (drum machines, etc.) │
│ │
│ Use cases for development: │
│ ✅ Test plugin with hardware MIDI controller │
│ ✅ Sync external gear to DAW clock │
│ ✅ Send test MIDI to vintage synth, process with plugin│
│ ✅ No need for separate MIDI interface ($50 saved) │
│ │
│ Comparison: │
│ • MOTU M4: MIDI IN + OUT ✅ │
│ • Focusrite 4i4: No MIDI ❌ │
│ • RME Babyface: No MIDI ❌ (discontinued in gen 2) │
│ • UA Apollo: No MIDI ❌ │
└──────────────────────────────────────────────────────────┘
Loopback Mode 🔁
Built-in, no software configuration needed:
┌──────────────────────────────────────────────────────────┐
│ Function: DAW Output 1/2 → Routed back to Input 3/4 │
│ │
│ Activation: Single button press (front panel) │
│ • No app needed (unlike Focusrite Control) │
│ • Instant toggle (great for A/B testing) │
│ │
│ Use cases: │
│ • Streaming/podcasting plugin testing │
│ • Re-record through different plugin chains │
│ • Measure plugin latency (loopback timing test) │
│ • Capture system audio + DAW mix simultaneously │
└──────────────────────────────────────────────────────────┘
⚠️ CONSIDERATIONS¶
No Digital I/O - No ADAT/SPDIF expansion - Stuck with 4 inputs maximum - Cannot integrate external preamps digitally - (Not an issue for most development work)
Basic Routing - No complex mixing like RME TotalMix - Simple: Inputs → DAW, DAW → Outputs - Cannot create separate headphone cue mix - (Sufficient for solo development)
USB 2.0 Bandwidth - 4in/4out is near USB 2.0 limit @ 192kHz - May have dropouts @ 192kHz on weak USB ports - (48/96kHz are rock-solid)
No Onboard DSP - All processing on CPU (like most interfaces) - No zero-latency effects while tracking - (Not a concern for plugin development)
🔧 CONFIGURATION STEP-BY-STEP¶
📥 STEP 1: DRIVER INSTALLATION¶
Windows (10/11)¶
1. Download MOTU M Series Drivers:
• Visit: motu.com/downloads
• Navigate: Audio Interfaces → M Series → M4
• Download: "MOTU M Series Installer" (latest)
• Version: 1.1.3+ (2024)
• File size: ~50MB
2. DO NOT connect M4 yet
3. Run installer:
• Install to default location
• Components:
✅ ASIO Driver (mandatory)
✅ MOTU M Series App (optional but recommended)
☐ WDM Driver (optional, not needed for pro work)
4. Reboot computer (required)
5. Connect MOTU M4 via USB-C:
• Use included cable (or any USB 2.0+ cable)
• Prefer USB 3.0 port for best stability
• M4 will power on (LCD lights up)
6. Windows auto-detection:
• "MOTU M4" device installed
• Device Manager → Sound controllers
• Should show: "MOTU M4 Audio"
7. Launch MOTU M Series App:
• Start Menu → MOTU → M Series
• Should show M4 connected (green checkmark)
• Firmware update if available (current: v1.0.9)
macOS (Monterey+)¶
Class-Compliant (Easiest Setup):
1. Connect MOTU M4 via USB-C:
• macOS recognizes IMMEDIATELY (no driver needed)
• Appears in: System Settings → Sound → Output
• Fully functional without any software
2. Install MOTU M Series App (optional):
• Download from motu.com/downloads
• Provides:
- Firmware updates
- Loopback routing control
- Advanced settings (sample rate lock, etc.)
• Install to: /Applications/MOTU M Series.app
3. Grant Permissions:
• System Settings → Privacy & Security
• Microphone: Allow [Your DAW]
• Input Monitoring: Allow MOTU M Series
4. Verify in Audio MIDI Setup:
• /Applications/Utilities/Audio MIDI Setup
• MOTU M4 appears in device list
• Configure: 4ch input, 4ch output
• Sample Rate: 48000 Hz (recommended)
🎛️ STEP 2: MOTU M SERIES APP¶
App Layout¶
┌─────────────────────────────────────────────────────────────┐
│ MOTU M Series - M4 Control Panel │
├─────────────────────────────────────────────────────────────┤
│ │
│ ┌─────────────────────────────────────────────────────┐ │
│ │ DEVICE INFO │ │
│ │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │ │
│ │ Model: MOTU M4 │ │
│ │ Firmware: v1.0.9 (Up to date ✅) │ │
│ │ Serial: M4-XXXXXX │ │
│ │ Sample Rate: 48000 Hz │ │
│ │ Buffer Size: 128 samples (set in DAW) │ │
│ └─────────────────────────────────────────────────────┘ │
│ │
│ ┌─────────────────────────────────────────────────────┐ │
│ │ SETTINGS │ │
│ │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │ │
│ │ Sample Rate Lock: │ │
│ │ ☐ 44.1/48 kHz only (recommended for consistency)│ │
│ │ ☑ Allow all rates (44.1-192kHz) │ │
│ │ │ │
│ │ LED Brightness: │ │
│ │ [────────●───────] 75% (adjustable) │ │
│ │ │ │
│ │ Meter Ballistics: │ │
│ │ ● Peak (fast response) │ │
│ │ ○ RMS (average level) │ │
│ │ │ │
│ │ Loopback Mode: │ │
│ │ ☐ Off (normal operation) │ │
│ │ ☑ On (Output 1/2 → Input 3/4) │ │
│ │ │ │
│ │ Direct Monitor: │ │
│ │ ☐ Off (hear DAW only) ✅ Recommended │ │
│ │ ☑ On (zero-latency input monitoring) │ │
│ └─────────────────────────────────────────────────────┘ │
│ │
│ ┌─────────────────────────────────────────────────────┐ │
│ │ FIRMWARE UPDATE │ │
│ │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │ │
│ │ Current: v1.0.9 │ │
│ │ Latest: v1.0.9 (No update available) │ │
│ │ │ │
│ │ [Check for Update] [Update Firmware] │ │
│ └─────────────────────────────────────────────────────┘ │
└─────────────────────────────────────────────────────────────┘
Key Settings Explained¶
Sample Rate Lock
☑ Allow all rates (44.1-192kHz):
• M4 adapts to DAW project sample rate
• Flexible (switch between projects easily)
• Risk: Accidental 192kHz selection (4× CPU load)
☐ 44.1/48 kHz only:
• Locks out high sample rates
• Prevents accidental CPU-intensive rates
• Recommended if you work @ 48kHz exclusively
• Must disable if client sends 96kHz files
LED Brightness
Adjustable: 0% (off) to 100% (blinding)
┌──────────────────────────────────────────────────────────┐
│ Recommended Settings: │
│ • Daylight studio: 75-100% (high visibility) │
│ • Evening work: 40-60% (less eye strain) │
│ • Late night (dark): 20-30% (comfortable) │
│ │
│ Pro tip: │
│ Set to 50% default, adjust per session lighting │
│ Saves power (slightly), reduces LED fade over time │
└──────────────────────────────────────────────────────────┘
Meter Ballistics
● Peak (Fast Response):
• Catches transients (drum hits, clicks)
• LEDs react instantly
• Best for: Preventing clipping
• Use for: Recording, live tracking
○ RMS (Average Level):
• Shows perceived loudness
• LEDs react slowly (averaged over time)
• Best for: Mixing, leveling
• Use for: Setting consistent gain
For AudioLab development: PEAK mode
• Catch distortion/aliasing artifacts (transient spikes)
• Visual feedback on plugin output peaks
Loopback Mode 🔁
How it works:
┌──────────────────────────────────────────────────────────┐
│ SIGNAL ROUTING WITH LOOPBACK ENABLED: │
│ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │
│ │
│ DAW Output 1/2 (e.g., plugin on Track 1) │
│ │ │
│ ├─→ Monitor Outputs (you hear it) 🔊 │
│ │ │
│ └─→ [Loopback] → Input 3/4 (DAW sees it) │
│ │ │
│ ▼ │
│ Track 2 armed on Input 3/4 │
│ (Records plugin output) │
│ │
│ USE CASES: │
│ ✅ Re-record through different plugin chain │
│ ✅ Test streaming setup (OBS reads Input 3/4) │
│ ✅ Measure plugin latency (loopback timing test) │
│ ✅ Bouncing with different settings (non-destructive) │
└──────────────────────────────────────────────────────────┘
ACTIVATION:
Method 1: MOTU M Series App → Loopback: ☑ On
Method 2: Front panel button (hold LOOPBACK for 2 sec)
LCD shows "LOOPBACK ON"
Direct Monitor
☐ Off (Recommended for plugin development):
• Input signals go ONLY to DAW
• You hear: DAW playback (includes your plugins)
• Latency: Subject to buffer size (2-10ms)
• Perfect for: Processing with AudioLab plugins
☑ On (Use when tracking):
• Input signals → DAW AND monitor outputs
• You hear: Direct input (0ms) + DAW playback
• Zero-latency monitoring for recording
• Downside: Bypasses plugin processing
For AudioLab work: Keep OFF
• You WANT to hear processed audio (with plugins)
• Direct monitoring would bypass your plugin
⚙️ STEP 3: ASIO / CORE AUDIO CONFIGURATION¶
Buffer Size Settings¶
┌────────────┬───────────────┬──────────────┬────────────────┐
│ Samples │ Latency │ CPU Load │ Use Case │
│ │ @ 48kHz │ │ │
├────────────┼───────────────┼──────────────┼────────────────┤
│ 32 │ 1.3ms RTL │ 🔴 Very High │ Live (if i9+) │
│ │ │ │ (M4 handles!) │
├────────────┼───────────────┼──────────────┼────────────────┤
│ 64 │ 2.5ms RTL │ 🟠 High │ Recording │
│ │ │ │ ✅ RECOMMENDED │
├────────────┼───────────────┼──────────────┼────────────────┤
│ 128 │ 4.3ms RTL │ 🟡 Medium │ Daily dev │
│ │ │ │ (if CPU limited)│
├────────────┼───────────────┼──────────────┼────────────────┤
│ 256 │ 8.0ms RTL │ 🟢 Low │ Debugging │
│ │ │ │ Complex projects│
└────────────┴───────────────┴──────────────┴────────────────┘
Note: MOTU M4 has exceptional low-latency performance
Can run 64 or even 32 samples very stably
Better than Focusrite/Behringer at same buffer
How to Set Buffer Size¶
Windows (ASIO):
Method 1: In DAW (Reaper example)
Options → Preferences → Audio → Device
→ ASIO: "MOTU M4"
→ "ASIO Configuration" button
→ Buffer Size: 64 samples ✅
Method 2: Standalone ASIO Panel
Start Menu → MOTU → "M Series ASIO Control Panel"
→ Buffer Size: 64 samples
→ Apply (global for all ASIO apps)
Verification:
Preferences → Audio → Device
→ Should show: "2.5ms input latency, 2.5ms output latency"
→ Total RTL: ~5ms (excellent)
macOS (CoreAudio):
DAW-Specific (per-app setting):
Reaper:
Preferences → Audio → Device
→ Audio Device: MOTU M4
→ Request Buffer Size: 64 samples
Logic Pro:
Preferences → Audio → Devices
→ I/O Buffer Size: 64 samples
→ "Low Latency Mode" can reduce further (auto-adjusts)
Ableton Live:
Preferences → Audio
→ Buffer Size: 64 samples
→ Driver Error Compensation: 0 samples (M4 doesn't need)
🎯 Optimal Setting for AudioLab Development¶
64 samples @ 48kHz ⭐ - Why: M4's drivers are VERY efficient - RTL: ~2.5ms (imperceptible, feels instant) - CPU: Manageable on i5/Ryzen 5+ or M1 Mac - Stability: Dropout-free even on laptops
128 samples as fallback - If: Running heavy debug builds (ASAN, Valgrind) - If: Older CPU (pre-2018 laptop) - RTL: Still good at ~4.3ms
32 samples for stress testing - Test: Can your plugin handle extreme low-latency? - M4 can actually run 32 stable (rare for USB 2.0) - Exposes threading issues, race conditions
📊 STEP 4: LCD METERING & MONITORING¶
Understanding the LCD Display¶
FRONT PANEL LCD (128×64 pixel monochrome):
┌──────────────────────────────────────────────────────────┐
│ ┌────────────────────────────────────────────────────┐ │
│ │ INPUT LEVELS │ │
│ │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │ │
│ │ 1: [▓▓▓▓▓▓▓░░░░] -12.3dBFS Peak │ │
│ │ 2: [▓▓▓▓▓░░░░░░] -18.7dBFS Peak │ │
│ │ 3: [░░░░░░░░░░░] -∞ dB (line input, unused) │ │
│ │ 4: [░░░░░░░░░░░] -∞ dB │ │
│ │ │ │
│ │ OUTPUT LEVELS │ │
│ │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │ │
│ │ L: [▓▓▓▓▓▓▓▓░░░] -6.1dBFS Main Monitor │ │
│ │ R: [▓▓▓▓▓▓▓▓░░░] -6.3dBFS │ │
│ │ │ │
│ │ STEREO CORRELATION │ │
│ │ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │ │
│ │ Phase: +0.85 [██████████░░░░] (Good stereo) │ │
│ │ -1.0 ←──┼──→ +1.0 (Mono) │ │
│ └────────────────────────────────────────────────────┘ │
│ │
│ Button: Press to cycle display modes: │
│ • Mode 1: Input levels (default) │
│ • Mode 2: Output levels + phase │
│ • Mode 3: Loopback status + sample rate │
└──────────────────────────────────────────────────────────┘
Reading the Meters¶
Peak vs. RMS:
LCD shows PEAK by default (catches transients):
┌──────────────────────────────────────────────────────────┐
│ PEAK MODE (default): │
│ • Displays: Highest instantaneous sample level │
│ • Hold time: 3 seconds (bar stays at peak) │
│ • Use for: Avoiding clipping │
│ • Ideal for: Recording, tracking │
│ │
│ RMS MODE (optional, set in M Series app): │
│ • Displays: Average level over 300ms window │
│ • More accurate for perceived loudness │
│ • Use for: Gain-staging, mixing │
│ • Ideal for: Leveling tracks, mastering │
│ │
│ For AudioLab development: Use PEAK │
│ • Catch distortion spikes from buggy plugins │
│ • See transient response (compressor attack times) │
│ • Verify peak limiting algorithms work correctly │
└──────────────────────────────────────────────────────────┘
Stereo Phase Correlation:
LCD bottom section shows phase relationship:
┌──────────────────────────────────────────────────────────┐
│ CORRELATION VALUES: │
│ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ │
│ +1.0: MONO (L = R exactly, summed to center) │
│ • Bad for: Stereo music │
│ • Good for: Bass, kick drum (mono content) │
│ │
│ +0.5 to +0.9: GOOD STEREO │
│ • Healthy width │
│ • Mono-compatible (won't disappear in mono) │
│ • Target for most mixes │
│ │
│ 0.0: WIDE STEREO │
│ • L and R are independent │
│ • Good for: Ambience, reverb │
│ • Risky for: Lead vocals (may sound weak) │
│ │
│ -0.5 to -1.0: OUT OF PHASE (DANGER!) │
│ • L and R are inverted │
│ • Mono playback = cancellation (silence!) │
│ • FIX: Check plugin polarity settings │
│ │
│ For AudioLab Stereo Plugins: │
│ • Wideners: Aim for 0.0 to +0.3 (wide but safe) │
│ • Compressors: Should NOT shift phase (+0.8 → +0.2) │
│ • Reverbs: -0.1 to +0.4 (decorrelated L/R) │
└──────────────────────────────────────────────────────────┘
LED Ring Interpretation¶
Each gain/volume knob has RGB LED ring:
┌──────────────────────────────────────────────────────────┐
│ INPUT 1/2 GAIN RINGS: │
│ 🟢 Green LEDs (bottom half): -∞ to -18dBFS (safe) │
│ 🟡 Yellow LEDs (top half): -18 to -6dBFS (good) │
│ 🔴 Red LED (12 o'clock): -3 to 0dBFS (danger) │
│ ⚫ All OFF: 0dBFS+ (CLIPPING!) │
│ │
│ MONITOR VOLUME RING: │
│ 🔵 Blue gradient: Output level indication │
│ (Not signal level; just knob position) │
│ │
│ HEADPHONE VOLUME RING: │
│ 🟣 Purple gradient: Knob position │
│ (Warning: Can get VERY loud, protect ears!) │
│ │
│ BEHAVIOR: │
│ • Peak hold: Highest LED stays lit for 3 seconds │
│ • Auto-dimming: Reduces brightness after 10sec idle │
│ • Clip flash: Red LED flashes rapidly if clipping │
└──────────────────────────────────────────────────────────┘
Developer tip:
Place M4 in peripheral vision while coding
Red flash on gain ring = "Check signal path!"
No need to Alt-Tab to DAW meters constantly
🔊 STEP 5: MONITORING SETUP¶
Output Routing¶
MOTU M4 has 4 independent outputs:
┌──────────────────────────────────────────────────────────┐
│ MAIN MONITOR L/R (Outputs 1/2) - Rear TRS jacks │
│ • Primary studio monitors │
│ • Volume: Front panel knob (large, center) │
│ • LED ring: Blue gradient (visual level) │
│ • Mute: Press knob (LED turns off) │
│ │
│ LINE OUT L/R (Outputs 3/4) - Rear TRS jacks │
│ • Fixed level (no volume control on hardware) │
│ • Always outputs at 0dBFS = full scale │
│ • Use cases: │
│ - External monitor controller │
│ - Alternate speaker system (with own volume) │
│ - Patch to external gear (reverb tank, etc.) │
│ │
│ HEADPHONE - Front panel 1/4" stereo jack │
│ • Mirrors Main Monitor 1/2 signal │
│ • Volume: Front panel knob (small, right side) │
│ • LED ring: Purple gradient │
│ • Independent from monitor volume │
│ • ⚠️ Can get VERY loud (protect hearing!) │
└──────────────────────────────────────────────────────────┘
Monitoring Configurations¶
SETUP 1: Standard Development
Most common setup:
┌──────────────────────────────────────────────────────────┐
│ CONNECTIONS: │
│ • Main Monitor 1/2 → Studio monitors (KRK, Yamaha, etc)│
│ • Headphones → Plugged into front jack │
│ • Line Out 3/4 → UNUSED │
│ │
│ DAW ROUTING (Reaper): │
│ • Master Track → Output: 1+2 (Main Monitor) │
│ • All project tracks route to Master (default) │
│ │
│ USAGE: │
│ • Code with speakers (Main Monitor volume @ reference) │
│ • Switch to headphones for detailed listening │
│ (Independent volume, turn down speakers to 0) │
│ • M4 headphone amp is VERY powerful (drives 250Ω easy) │
└──────────────────────────────────────────────────────────┘
SETUP 2: Dual Monitor (A/B Speaker Comparison)
Compare plugin on two different speaker systems:
┌──────────────────────────────────────────────────────────┐
│ CONNECTIONS: │
│ • Main Monitor 1/2 → Primary monitors (e.g., KRK Rokit)│
│ • Line Out 3/4 → Reference monitors (e.g., Auratone) │
│ (Via external monitor controller with volume control) │
│ │
│ DAW ROUTING: │
│ • Master Track → Output: 1+2 AND 3+4 (both!) │
│ │
│ EXTERNAL MONITOR CONTROLLER: │
│ • Inputs: M4 Outputs 1/2 AND 3/4 │
│ • A/B switch: Toggle between speaker systems │
│ • Single volume knob (control both systems) │
│ • Example units: Mackie Big Knob, PreSonus Monitor Station│
│ │
│ WHY THIS WORKS: │
│ • Line Out 3/4 is fixed level (no M4 volume control) │
│ • External controller handles switching + volume │
│ • Hear plugin on multiple speaker types (translation) │
└──────────────────────────────────────────────────────────┘
SETUP 3: Loopback for Plugin Chain Testing
Route DAW output back into DAW input:
┌──────────────────────────────────────────────────────────┐
│ ENABLE LOOPBACK: │
│ • MOTU M Series App → Loopback: ☑ On │
│ • OR: Press front panel "LOOPBACK" button (hold 2sec) │
│ • LCD shows: "LOOPBACK ON" │
│ │
│ SIGNAL FLOW: │
│ ┌────────────────────────────────────────────────────┐ │
│ │ Track 1: Pink noise test signal │ │
│ │ └─→ AudioLab EQ Plugin │ │
│ │ └─→ Output 1/2 │ │
│ │ │ │ │
│ │ ├─→ Speakers (you hear it) 🔊 │ │
│ │ │ │ │
│ │ └─→ [Loopback] → Input 3/4 │ │
│ │ │ │ │
│ │ Track 2: Record-armed │ │
│ │ ├─ Input: 3/4 (receives EQ'd signal) │ │
│ │ └─→ AudioLab Compressor │ │
│ │ └─→ Output 1/2 │ │
│ │ │ │
│ │ RESULT: Test EQ → Compressor chain interaction │ │
│ └────────────────────────────────────────────────────┘ │
│ │
│ USE CASES: │
│ • Does your EQ play nice BEFORE your compressor? │
│ • Does compressor react correctly to EQ'd signal? │
│ • Measure total latency of plugin chain │
└──────────────────────────────────────────────────────────┘
🎹 STEP 6: MIDI CONFIGURATION¶
MIDI Connections¶
REAR PANEL: 5-pin DIN jacks (classic MIDI)
┌──────────────────────────────────────────────────────────┐
│ MIDI IN: │
│ • Receive from: Hardware controllers, synths, drum machines│
│ • Example setup: │
│ Akai MPK Mini → MIDI OUT → M4 MIDI IN → Computer │
│ │
│ MIDI OUT: │
│ • Send to: External gear (sync clock, send notes) │
│ • Example setup: │
│ Computer → M4 MIDI OUT → Elektron Digitakt MIDI IN │
│ │
│ MIDI THRU: │
│ • Not available (M4 only has IN + OUT) │
│ • To chain devices: Use software MIDI routing in DAW │
└──────────────────────────────────────────────────────────┘
DAW MIDI Setup¶
Windows (Reaper example):
Options → Preferences → MIDI Devices
┌──────────────────────────────────────────────────────────┐
│ MIDI Inputs: │
│ ☑ Enable: "MOTU M4 MIDI IN" │
│ (Appears automatically after driver install) │
│ │
│ MIDI Outputs: │
│ ☑ Enable: "MOTU M4 MIDI OUT" │
│ │
│ TESTING: │
│ 1. Connect MIDI controller to M4 MIDI IN │
│ 2. Reaper → View → MIDI Event List │
│ 3. Play notes on controller │
│ 4. Should see: "Note On C4 velocity 64" messages │
└──────────────────────────────────────────────────────────┘
macOS (Logic Pro example):
Logic Pro → Preferences → MIDI
┌──────────────────────────────────────────────────────────┐
│ MIDI Inputs: │
│ ☑ MOTU M4 (auto-detected, no config needed) │
│ │
│ MIDI Outputs: │
│ ☑ MOTU M4 │
│ │
│ TESTING: │
│ Window → Show MIDI Activity │
│ • Green bars should light up when playing controller │
└──────────────────────────────────────────────────────────┘
AudioLab Plugin MIDI Testing¶
Scenario: Test your plugin with hardware MIDI controller
┌──────────────────────────────────────────────────────────┐
│ SETUP: │
│ ┌────────────────────────────────────────────────────┐ │
│ │ MIDI Controller (e.g., Akai MPK Mini) │ │
│ │ │ │ │
│ │ ├─ MIDI Cable → M4 MIDI IN │ │
│ │ │ │ │ │
│ │ │ ▼ │ │
│ │ │ Computer receives MIDI │ │
│ │ │ │ │ │
│ │ │ ▼ │ │
│ │ │ DAW Track (MIDI input enabled) │ │
│ │ │ │ │ │
│ │ │ ▼ │ │
│ │ │ AudioLab Synth Plugin │ │
│ │ │ (receives MIDI notes) │ │
│ │ │ │ │ │
│ │ │ ▼ │ │
│ │ │ Audio Output (M4 Out 1/2) │ │
│ └────────────────────────────────────────────────────┘ │
│ │
│ DAW SETUP (Reaper): │
│ 1. Create MIDI track │
│ 2. Track input: "MOTU M4 MIDI IN" + Channel 1 │
│ 3. Insert: AudioLab Synth Plugin │
│ 4. Record-arm track (or enable input monitoring) │
│ 5. Play controller → Should hear plugin output │
│ │
│ TESTING SCENARIOS: │
│ • Does plugin respond to Note On/Off correctly? │
│ • Does velocity sensitivity work? │
│ • Does sustain pedal (CC 64) work? │
│ • Does pitch bend work? │
│ • Does mod wheel (CC 1) work? │
└──────────────────────────────────────────────────────────┘
🔧 TROUBLESHOOTING¶
❌ PROBLEM: "No audio output"¶
MOTU M4 SPECIFIC CHECKS:
┌──────────────────────────────────────────────────────────┐
│ 1. CHECK MONITOR VOLUME KNOB: │
│ • Is it turned up? (LED ring should be visible) │
│ • Press knob: Unmutes if accidentally muted │
│ • LED off = muted (press to unmute) │
│ │
│ 2. CHECK LCD DISPLAY: │
│ • Press LCD button to cycle to output meters │
│ • Should see output bars moving when DAW plays │
│ • If moving on LCD but no sound → speaker issue │
│ • If NOT moving → routing issue │
│ │
│ 3. VERIFY DAW OUTPUT ROUTING: │
│ Reaper: Master track → Output: 1+2 │
│ Logic: Stereo Out → M4 Outputs 1-2 │
│ │
│ 4. CHECK PHYSICAL CONNECTIONS: │
│ • Speakers plugged into Main Out 1/2 (rear, TRS) │
│ • NOT Line Out 3/4 (different jacks) │
│ • Cables fully inserted (TRS = 2 clicks) │
│ │
│ 5. TEST WITH HEADPHONES: │
│ • Plug into front headphone jack │
│ • Turn headphone volume knob up │
│ • If headphones work, monitors work → speaker issue │
│ │
│ 6. RESET M4 TO DEFAULTS: │
│ • Disconnect USB │
│ • Hold front panel LCD button │
│ • Reconnect USB while still holding │
│ • Hold for 5 seconds → Factory reset │
│ • LCD shows "RESET" → Release button │
└──────────────────────────────────────────────────────────┘
❌ PROBLEM: "Clicks, pops, dropouts"¶
M4-SPECIFIC SOLUTIONS:
┌──────────────────────────────────────────────────────────┐
│ 1. INCREASE BUFFER SIZE (Least likely with M4): │
│ • M4 drivers are very efficient │
│ • Try 128 instead of 64 (if issues persist) │
│ • Still having dropouts @ 128 = other problem │
│ │
│ 2. UPDATE FIRMWARE (Common fix): │
│ • Open MOTU M Series App → Firmware Update │
│ • Current version: v1.0.9 (2024) │
│ • Older firmware had USB disconnect issues │
│ │
│ 3. USB PORT SELECTION: │
│ • Try USB 3.0 port (blue) - better power delivery │
│ • AVOID: USB hubs (even powered) │
│ • AVOID: Front panel USB (shared bandwidth) │
│ • BEST: Rear motherboard USB 3.0 directly │
│ │
│ 4. DISABLE USB SELECTIVE SUSPEND (Windows): │
│ • Control Panel → Power Options │
│ • Change plan settings → Advanced │
│ • USB Settings → Selective Suspend → Disabled │
│ │
│ 5. CHECK SAMPLE RATE MISMATCH: │
│ • DAW project: 48kHz │
│ • M4 current rate: Check LCD (press button) │
│ • Windows Sound: 48kHz (if using WDM) │
│ • Mismatch = resampling = dropouts │
│ │
│ 6. MACBOOK SPECIFIC: DISABLE THUNDERBOLT AUDIO │
│ • Some Macs try to use TB audio instead of USB │
│ • Audio MIDI Setup → Hide "MacBook Pro Speakers" │
│ • Prevents accidental device switching │
└──────────────────────────────────────────────────────────┘
❌ PROBLEM: "LCD display not working / dim"¶
┌──────────────────────────────────────────────────────────┐
│ 1. CHECK LED BRIGHTNESS SETTING: │
│ • MOTU M Series App → LED Brightness: Increase │
│ • Try 100% to verify LCD functional │
│ │
│ 2. LCD AUTO-DIM FEATURE: │
│ • LCD dims after 30 seconds of no interaction │
│ • Press any button → Full brightness returns │
│ • This is normal behavior (energy saving) │
│ │
│ 3. RESET TO DEFAULTS: │
│ • Disconnect USB │
│ • Hold LCD button + Loopback button simultaneously │
│ • Reconnect USB while holding both │
│ • Hold for 10 seconds → Deep reset │
│ • LCD should show "INIT" → Release buttons │
│ │
│ 4. FIRMWARE CORRUPTION (Rare): │
│ • MOTU M Series App → Force Firmware Update │
│ • Downloads firmware even if "up to date" │
│ • Re-flashes firmware (fixes corruption) │
│ │
│ 5. HARDWARE ISSUE: │
│ • If none of above work → Contact MOTU support │
│ • Warranty: 2 years (check serial number) │
│ • Email: support@motu.com │
└──────────────────────────────────────────────────────────┘
❌ PROBLEM: "Loopback not working"¶
┌──────────────────────────────────────────────────────────┐
│ 1. VERIFY LOOPBACK ENABLED: │
│ Method 1: MOTU M Series App → Loopback: ☑ On │
│ Method 2: Front panel → Hold LOOPBACK button (2sec) │
│ LCD should show: "LOOPBACK ON" │
│ │
│ 2. CHECK DAW INPUT ROUTING: │
│ • Track must be set to Input 3/4 (NOT 1/2) │
│ • Loopback routes: Output 1/2 → Input 3/4 │
│ • Verify in DAW track input selector │
│ │
│ 3. ENSURE SOMETHING IS PLAYING: │
│ • Another track must output to 1/2 (and be audible) │
│ • Check master fader is up │
│ • Check track is not muted/soloed │
│ │
│ 4. RECORD-ARM RECEIVING TRACK: │
│ • Track receiving loopback must be armed │
│ • OR: Enable input monitoring (track "I" button) │
│ │
│ 5. CHECK FOR SAMPLE RATE MISMATCH: │
│ • Loopback is DIGITAL routing (sample-rate-dependent)│
│ • DAW project SR must match M4 current SR │
│ • Check LCD: Press button → Shows current SR │
│ │
│ 6. RESTART INTERFACE: │
│ • Disable loopback │
│ • Disconnect M4 USB │
│ • Wait 10 seconds │
│ • Reconnect │
│ • Re-enable loopback │
└──────────────────────────────────────────────────────────┘
📚 ADDITIONAL RESOURCES¶
🌐 Official MOTU Resources
motu.com/products/proaudio/m4
• Product page, specs, downloads
📖 MOTU M4 User Guide (PDF)
motu.com/download/product/624/M%20Series%20User%20Guide.pdf
32 pages, read:
• Chapter 2: Connections (pages 5-10)
• Chapter 4: M Series App (pages 15-20)
• Chapter 6: Troubleshooting (pages 28-30)
🎥 MOTU YouTube Channel
youtube.com/@MOTUdotcom
Watch: "MOTU M Series: Complete Setup Guide"
💬 MOTU Community Forum
forum.motu.com/
Active users, MOTU staff occasionally respond
📱 MOTU Support
Email: support@motu.com
Phone: +1-617-576-2760 (M-F 9am-6pm EST)
Response time: 1-2 business days
🎯 QUICK REFERENCE¶
╔══════════════════════════════════════════════════════════╗
║ MOTU M4 CHEAT SHEET ║
╠══════════════════════════════════════════════════════════╣
║ FUNCTION │ CONTROL ║
╟────────────────────────┼─────────────────────────────────╢
║ Gain (Inputs 1/2) │ Hardware knobs (front panel) ║
║ 48V Phantom Power │ Button per input (LED=active) ║
║ Pad (-20dB) │ Button per input (LED=active) ║
║ ━━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ║
║ Monitor Volume │ Large knob (center, front) ║
║ Monitor Mute │ Press monitor knob (LED off) ║
║ Headphone Volume │ Small knob (right, front) │
║ ━━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ║
║ Loopback Toggle │ Hold LOOPBACK button (2 sec) ║
║ LCD Display Mode │ Press LCD button (cycles) ║
║ Direct Monitor │ M Series App (no hardware btn) ║
║ ━━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ║
║ Factory Reset │ Hold LCD while plugging USB ║
║ Firmware Update │ M Series App → Update tab ║
╚══════════════════════════════════════════════════════════╝
Optimal Settings for AudioLab Development:
Sample Rate: 48 kHz
Buffer Size: 64 samples (M4 handles it beautifully)
Direct Monitor: OFF (hear DAW output with plugins)
Loopback: OFF (unless specifically testing)
LCD Brightness: 50-75% (adjust per lighting)
Meter Ballistics: PEAK (catch transients)
Monitor Level: Calibrated to 85dB SPL @ -18dBFS
LED Rings: 50% brightness (comfortable)
Document Status: ✅ Complete Interface: MOTU M4 Firmware Version: 1.0.9+ (check via M Series App) Driver Version: Latest from motu.com/downloads Maintained By: AudioLab DevOps Team