What is PTP in Audio Networks?
Why it exists
Two devices converting audio at a nominal 48 kHz will not run at exactly the same rate. Left alone, they drift. On a digital audio link, drift means samples are eventually dropped or repeated — audible as clicks, then dropouts.
PTP solves this by distributing one reference time across the network. Devices exchange timestamped messages, measure the delay between them, and steer their local oscillators to match.
Key numbers
| Property | Typical value |
|---|---|
| Sync accuracy | Under 1 µs on a well-configured LAN |
| Sync message rate | 8 per second (default) |
| Announce interval | 1 per second |
| Grandmasters per domain | Exactly one active |
How it fails
- Two queriers or two domains — devices split into groups following different masters
- QoS not applied to clock packets — clock messages queue behind audio, jitter rises
- Energy Efficient Ethernet — ports sleeping between packets add unpredictable delay
- Wi-Fi in the clock path — never carry PTP over wireless
Frequently asked
What is the difference between PTPv1 and PTPv2?
PTPv1 (IEEE 1588-2002) is used by native Dante. PTPv2 (IEEE 1588-2008) is used by AES67 and most broadcast systems. They are not interoperable, which is why bridging Dante to AES67 requires careful clock planning.
How is the grandmaster chosen?
By the Best Master Clock Algorithm, which compares advertised clock quality, priority fields and finally MAC address. You can force a preferred grandmaster by setting its priority value.