Installation manual

UEX/650 Upgrade Kit Installation
7
Professional video equipment uses a variation of this interface, where the P-P digital
audio signal is 1V. The decoding circuit handles both levels automatically. BNC
(“push and twist”) connectors are used for the digital audio signal on professional
video equipment. Like the use of XLR connectors on pro audio equipment, the
adoption of BNC connectors for pro video stems from their existing use for the video
signal. Again, you can use high-quality 75 ohm video cables with BNC connectors.
Alternatively, you can use high-quality RCA (phono plug) video cables with BNC
adapters since the cable and impedance are the same.
Multiple Sources—Conversion Between Interface Standards
If you intend to switch between multiple digital audio sources, DO NOT attempt to
convert a digital interface type by directly wiring an XLR connector to a BNC or
RCA plug. This will cause an impedance mismatch and signal reflections, resulting in
degradation of the digital waveform. It may seem to work, but the results will prove
unreliable and dropouts will occur.
With one digital audio input on the CP650, it may seem difficult to switch between
multiple units that use different digital output standards. It is actually easy to convert
from one interface to the other. A simple and economical method is to use inline
transformers. These devices perform the necessary impedance and connector
conversion between AES/EBU and S/PDIF signals. With the digital outputs of all
units converted to the same interface standard, a patchbay or a router/switcher can be
used for selecting which output is connected to the single digital input of the CP650.
The table below shows some examples of AES/EBU ↔ S/PDIF adapters. The
S/PDIF connector in these examples is a BNC. BNC-to-RCA adapters can be added
to connect to consumer S/PDIF outputs. The units listed below are of the “passive”
type.
Adapter Type Neutrik



Canare



Female XLR 110 Ω In
to BNC Female 75 Ω Out
NA-BF BCJ-XJ-TRA
BNC Female 75 Ω In
to Male XLR 110 Ω Out
NA-BM BCJ-XP-TRA
Higher-priced units are available incorporating active circuitry that offer additional
features like multiple inputs, inputs for Toslink

(fiber optic) digital connections, and
multiple outputs.