Apollo 8p Hardware Manual
(30) Word Clock I/O
Word Clock In
Apollo 8p’s internal clock can be synchronized (slaved) to an external master word
clock. This is accomplished by setting Apollo 8p’s clock source to Word Clock within the
Console application, connecting the external word clock’s BNC connector to Apollo 8p’s
word clock input, and setting the external device to transmit word clock. If Apollo 8p is
the last device in the clock chain, the Termination switch (#10) should be engaged.
Important: Apollo 8p’s sample rate must be manually set to match the incoming
clock’s sample rate.
Note: Apollo 8p can be synchronized to an external “1x” clock signal only. Super-
clock, overclocking, and subclocking are not supported.
Word Clock Out
This BNC connector transmits a standard (1x) word clock when Apollo 8p is set to use its
internal clock. The clock rate sent by this port matches the current system sample rate,
as speciﬁed within the Console application.
When Apollo 8p is set to use external word clock as its clock, Apollo 8p is a word clock
slave. If the incoming external word clock is within ±0.5% of a supported sample rate
(44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, 192 kHz), Word Clock Out will mirror
Word Clock In with a slight phase delay (about 40ns).
Because Apollo 8p’s word clock output is not a true mirror of the word clock input, word
clock out should not be used to daisy chain the word clock if Apollo 8p is in the middle
of the word clock chain. The correct method to connect Apollo 8p in the middle of a
word clock chain is to use a T-connector at Apollo 8p’s word clock input and leave Apollo
8p’s word clock output unconnected (the Termination switch should not be engaged in
(32) Thunderbolt 2 Ports
Apollo 8p has two Thunderbolt 2 ports. One port is used to connect Apollo 8p to a
Thunderbolt 1 or Thunderbolt 2 port on the host computer. Thunderbolt peripheral
devices may be serially connected (daisy-chained) to the second Thunderbolt port.
When Apollo 8p is properly communicating with the host computer via Thunderbolt, the
HOST indicator (#13) illuminates.
Thunderbolt Bus Power
Per the Thunderbolt speciﬁcation, bus power is supplied to downstream (daisy-chained)
Thunderbolt peripheral devices. Apollo 8p must be powered on for the daisy-chained
peripheral to receive Thunderbolt bus power.