M2tech, Using the external clock, Aes/ebu output: consumer and professional mode – M2TECH hiFace Evo User Manual

Page 22: S output

ace

192

/24bit digital audio interface

REVISION 1.o – JULY 2010

M2Tech

www.m2tech.biz

8. Using the external clock

When a very high precision and stability clock source is available, an external clock can be
applied to hiFace Evo on the related BNC input (Figure 1, 2). Whenever the clock is
present with the right voltage, the LED indicator (Figure 1, 7) will lit in green and the
hiFace Evo will automatically revert to the external clock.
Of course, the automatic clock switching to accommodate both 44.1kHz-based and 48kHz-
based sampling frequencies will be disabled, as the interface will be clocked with the
external clock. So, clock switching must be performed at the clock source. Otherwise, only
one base sampling frequency files should be chosen for playback.
For example, if a 24.576MHz external clock is applied, 48kHz, 96kHz and 192kHz files will
be played back with the right pitch, while 44.1kHz, 88.2kHz and 176.4kHz files will have a
higher pitch than normal and will sound hurried-up.
Conversely, when using a 22.5792MHz external clock, 44.1kHz, 88.2kHz and 176.4kHz
files will be played back with the right pitch, while 48kHz, 96kHz and 192kHz files will have
a lower pitch than normal and will sound slowed down.
The external clock can also be used to play files with a base frequency different than those
available internally. For example, a 32kHz file can be correctly played back using a
16.384MHz external clock.

9. AES/EBU output: consumer and professional mode

The AES/EBU output can be set to either consumer (default) or professional mode. The
difference is in the channel status bits content and meaning. The mode can be set by a
jumper inside the unit. M2Tech recommends users who want to change the mode of
the AES/EBU output to contact their dealer: opening the case will void the warranty.
The AES/EBU output setting doesn’t affect other outputs.

10. I

S output

The I

S output provides raw I

S data out of the hiFace Evo on an RJ-45 socket. It has no

galvanic isolation so its ground connection is same as the USB one. Pinout is as follows
(pins are listed from left to right):

2,4,6,8) Ground
1) SDATA
3) LRCK
5) SCLK
7) MCLK

Lines are driven by high-speed, high-current buffers capable of 25mA current drive on
each line.