AES10 / MADI Multichannel Audio Digital Interface
AES10, commonly known as MADI (Multichannel Audio Digital Interface), carries up to 64 channels of digital audio over a single cable—either 75 ohm coax or optical fiber. Operating at 48, 96, or 192 kHz with transparent PCM or compressed audio, MADI consolidates massive channel counts that would otherwise require dozens of AES3 pairs. Widely deployed in broadcast, large live sound venues, and recording facilities, MADI is the de facto standard for console/interface interconnect when channel density is critical.
MADI comes in two variants: coaxial (3 Gbps over 75 ohm, ~300 m) and optical (multimode 62.5/125 um, ~2 km+). Both operate identically at the audio layer; choice depends on distance and EMI environment.
Key Specifications
Channel Capacity: 64 channels (32 or 56 in legacy mode, rarely used). Per-channel up to 24-bit depth.
Sample Rates: 48, 96, 192 kHz, selectable per cable.
Coax Transport: 3 Gbps LVDS (Low Voltage Differential Signaling) on 75 ohm cable; BNC connectors. Distance ~300 m (site-dependent on cable quality). Backward compatible with earlier 125 Mbps MADI variants.
Optical Transport: ST or LC connectors; multimode fiber carries ~2 km. Eliminates ground loops and EMI; preferred for long distances and RF-noisy environments.
Frame Format: Multiplex frame contains 64 consecutive audio samples (one per channel) plus sync/status bits. Receiver reconstructs all 64 channels at clock frequency.
Timecode: SMPTE timecode can be embedded in MADI subframes; useful for broadcast/video sync.
Redundancy: Dual MADI cables with automatic switchover supported on professional mixing consoles; ensures failover without dropout.
Practical Application for AV
MADI excels where channel count and distance outweigh cost. A concert venue with 48-channel digital mixing console can send all outputs (main, monitoring, recording) via one MADI cable to a broadcast encoder, eliminating 48 individual AES3 connections.
Common deployments:
- Live sound: Digico, Yamaha, Soundcraft consoles with MADI output feed FOH processors, monitor send interface, and recording all on one cable.
- Broadcast: Studio mixing consoles (Studer, Euphonix) patch MADI to router matrices, on-air recorders, and multitrack archiving.
- RF-hostile environments: Optical MADI immune to RF/EMI; transmission trucks and outdoor events favor fiber.
- Virtual soundchecks: Venue's console captures MADI output to multitrack recorder, allowing artist to review/remix live performance offline.
MADI simplifies cabling in rack rooms: a single MADI patchbay replaces a wall of 48 AES3 jacks. Breakout devices convert MADI to AES3 or analog if needed downstream.
Disadvantages: MADI lacks real-time monitoring and delay; audio-over-IP systems (Dante, AES67) now offer lower latency and more flexible routing. MADI remains superior for fixed, high-density, non-networked scenarios.
Common Pitfalls
- Impedance mismatch: Mixing 75 ohm MADI coax with standard audio cable; reflections cause jitter and loss of channels. Always use proper 75 ohm MADI-rated coax, BNC terminators.
- Optical cable dirt: Dust on ST/LC connectors; intermittent optical sync loss. Clean connectors with proper optical wipes before connecting.
- Clock chaos: MADI receiver expects word-clock input, but cable carries both clock and audio. Verify device is in "MADI sync" or "internal clock from MADI" mode; don't feed external word-clock to MADI input simultaneously.
- Legacy vs. modern: Older 125 Mbps MADI devices on 3 Gbps cable; negotiation fails. Verify all devices are same generation (modern 3 Gbps) or have compatible fallback modes.