Metric Halo Mobile I/O - Manual (Page 77)

ULN-2 Users Guide
77
On output, the situation is a bit more complex. If you are driving an unbalanced load, you will get the best
performance by not connecting the ring of the TRS jack to ground. In order to do this, you can simply use
a balanced TRS/TRS connector with the unbalanced gear. You can also construct a special cable with a TRS
connector and a TS connector. In this cable, you just let the ring of the TRS connector float:
NO CONNECTION
TIP
TIP
SLEEVE (SHIELD)
SLEEVE (SHIELD)
BALANCED 1/4" TRS CONNECTOR
UNBALANCED 1/4" TS CONNECTOR
Figure 6.15: TRS to TS Unbalanced Cable
Alternatively, the TS connector can be replaced with an RCA connector for interfacing with gear that has RCA
unbalanced interconnects.
NO CONNECTION
TIP
PIN
SLEEVE (SHIELD)
BARREL (SHIELD)
BALANCED 1/4" TRS CONNECTOR
RCA CONNECTOR
Figure 6.16: TRS to RCA Unbalanced Cable
MAKING THE 1/4” CONNECTION
When you connect a 1/4” plug to a ULN-2 jack, insert it straight and firmly, ensuring that the plug is fully
inserted into the jack. If the plug is not fully inserted you will get level shifts, phase flips, distortion, or no sound.
To disconnect a 1/4” plug, firmly pull the plug straight out from the connector body. The connectors on ULN-2
are stiff, so you may have to exert some force to remove the plug.
MAKING THE XLR CONNECTION
When you connect a Male XLR plug to a ULN-2 jack, ensure that you have aligned the pins with the connector
body and insert firmly until the retention tab clicks.
To disconnect the plug, press the metal retention tab flush against the box, and pull the plug from the ULN-2.
Copper-Based Digital Audio
ULN-2 supports 2 channels of digital audio over copper-based connections. These connections can be made
using either S/PDIF interconnects with the RCA connectors or with AES interconnects using the XLR connectors.
Even though only one of the AES or S/PDIF inputs can be active at any given time, you can have different digital
sources connected to each of the input connectors at the same time – you use the MIO Console application to
select the active input. Audio routed to the digital outputs will be mirrored by both S/PDIF and AES outputs.
This allows you to send the same stereo pair to two devices at once.
We recommend that you use the AES interconnect mechanism to establish the digital communication between
the ULN-2 and other digital devices. The jitter and electrical noise tolerance on AES interconnects is substan-
tially better than with S/PDIF interconnects. The AES interconnect standard is equivalent to balanced audio
interconnections. If you need to use S/PDIF interconnects, try to use the shortest cables you can and, if possible,
use special purpose 75 ohm S/PDIF or video cables.
The RCA connectors used for S/PDIF are friction fit coaxial connectors. When you connect them, ensure that
they are fully inserted and tight.