MIDI, Sync, and Networked Audio

The MIDI Protocol

MIDI — Musical Instrument Digital Interface — was standardized in 1983. The original spec uses a 5-pin DIN connector and a serial data stream. Despite being over forty years old, the protocol is still the backbone of how electronic instruments communicate. It carries:

• Note messages: Note on, note off, and velocity (how hard the key was struck). These are the core of MIDI — the instructions that make instruments play.
• Control Change (CC): Knob movements, slider positions, pedal data. Volume, pan, modulation, filter cutoff — any continuous controller is a CC message.
• Program Change: Switches presets or patches on the receiving device.
• Pitch Bend: Continuous pitch shifting, typically from a wheel or joystick.
• Clock: Tempo pulses for synchronizing devices (more on this below).

MIDI supports 16 channels on a single connection — meaning one cable can carry 16 independent streams of data. A single keyboard can control 16 different instruments on 16 channels simultaneously. In practice, most home studio setups use one or two channels.

MIDI Over USB

Modern controllers use USB instead of 5-pin DIN. The protocol is identical — same messages, same channel structure. USB is faster, bidirectional (no separate MIDI in and out cables), and doesn’t require a standalone MIDI interface. Most controllers manufactured in the last decade are USB-only.

Clock and Sync

When multiple devices need to play together — a DAW, a hardware drum machine, a sequencer — they need to agree on tempo and timing. Several sync standards exist:

MIDI Clock sends 24 pulses per quarter note. Simple and widely supported. One device is the “leader” (sends clock), the rest are “followers” (lock to it). MIDI Clock carries tempo but not position — if you start playback at bar 17 in your DAW, a follower device doesn’t know it should also jump to bar 17. It just starts running at the right tempo from wherever it was.

MIDI Time Code (MTC) carries actual position — hours, minutes, seconds, and frames. Used for synchronizing to video and for studio automation systems that need to lock to a specific point in time, not just a tempo.

Word Clock is not MIDI at all — it’s a dedicated digital timing signal (BNC connector) that synchronizes the sample clocks of multiple A/D and D/A converters. When you connect two digital audio devices, they need to agree on exactly when each sample happens. If they don’t share a word clock, you get clicks, pops, and pitch drift. One device is the clock master; everything else follows.

Networked Audio

In large studios and live sound, audio needs to travel between rooms, stages, and devices over distances and channel counts that analog cables can’t handle. Digital audio networking solves this.

MADI (Multichannel Audio Digital Interface): Up to 64 channels over a single BNC or fiber optic cable. Point-to-point — one cable between two devices. Used in broadcast studios, live sound, and large recording facilities.

Dante (Digital Audio Network Through Ethernet): Audio routed over standard Ethernet networks using regular cables and switches. Hundreds of channels, low latency, and any device on the network can send to any other device. Dante is the current standard for networked audio in concert venues, houses of worship, and large production facilities.

Digital Audio Interconnects

Before networked audio, there are simpler point-to-point digital formats you’re more likely to encounter:

• S/PDIF — comes in two flavors: coaxial (over RCA) and optical (over TOSLINK fiber). Carries two channels of digital audio. Common on consumer and prosumer interfaces.
• ADAT Lightpipe — sends 8 channels of audio over a single optical cable. Many mid-range interfaces include ADAT I/O, making it one of the most practical ways to expand your channel count.
• AES/EBU — the professional digital standard, carried over XLR cables. Similar to S/PDIF in concept but with a different electrical specification designed for longer cable runs and professional environments.

These formats require all connected devices to share the same word clock — the master timing reference that keeps digital audio samples synchronized. When clock synchronization fails, you’ll hear distinctive artifacts: clicks, pops, or a harsh distortion that sounds like nothing else. If you hear it, check your clock source.

AVB (Audio Video Bridging): An open standard similar to Dante, built into some interfaces. AES67: An interoperability standard that lets different networked audio protocols communicate with each other.

Networked audio is less common in home studios today, but the technology is becoming more accessible. If you end up working in live sound, broadcast, or commercial studios, you’ll encounter Dante or MADI on day one — and the principles are increasingly showing up in home-studio-scale products.

What to Practice

1. Send MIDI from your DAW to a controller. If you have a hardware synth or a MIDI-capable keyboard, set up a MIDI track in your DAW and play notes from the software. Watch the hardware respond. That’s MIDI in action — instructions traveling from computer to instrument.
2. Explore MIDI channels. Set up two software instruments on two different MIDI channels. Send notes to each one from the same controller by switching channels. Understand that MIDI channels are addresses — they route data to the right destination.
3. Test MIDI Clock. If you have a hardware drum machine or sequencer, set your DAW as the clock master. Start playback — the hardware should follow. Change the tempo in the DAW — the hardware should follow that too. If it doesn’t, check which device is set to send and which to receive clock.
4. Check your word clock. If you have multiple digital audio devices (two interfaces, or an interface and a digital mixer), determine which one is the clock master. Most of the time, your primary interface should be the master and everything else should follow. If you hear intermittent clicks during playback, a word clock mismatch is a likely culprit.