Behringer BCA2000 - Manual (Page 20)

20
B-CONTROL AUDIO BCA2000
6. CONNECTIONS AND FORMATS
6.1 Glossary
Some technical terminology and acronyms that you may
encounter while working with the BCA2000 are explained in this
glossary. Explanations of additional terminology can be found in
our online glossary at www.behringer.com. You can find more
information about surround sound in the surround manual of our
digital mixing console DDX3216, which can be downloaded from
our website free of charge at www.behringer.com.
AC-3
More widely known as → DOLBY ® DIGITAL, AC-3 is the most
popular surround format today. Six separate digital sound
channels are data-compressed, encoded and → decoded
(front left, front right, front middle/center, rear left, rear right and
sub-bass channel, called → LFE).
The BCA2000 can reproduce this data format through the
digital outputs, provided your audio software contains a DOLBY ®
DIGITAL → decoder. This can be an audio application that uses
a software decoder as a → Plug-In or a DVD disc that is
reproduced on your computer’s DVD drive.
The six-channel music signal is then AC-3-encoded
( → Encoder), connected to a surround receiver with a digital
input (or similar) via one of the digital outputs and decoded
internally by the receiver’s AC-3 → Decoder, and then reproduced
on the six analog speaker outputs.
ADAT
®
The eight-channel digital audio format ADAT ® owes its name to
the first 8-track digital recorder from Alesis. The ADAT ® format
has established itself as the multi-channel standard of choice,
generally supporting 44.1 and 48 kHz → Sample Rates.
88.2 and 96 kHz sample rates are also possible, but only with
four (instead of eight) digitally transmitted channels. This version
is called → S/MUX.
Just a single optical cable (very thin optical fiber) is required to
transmit all eight (or four) channels of an ADAT ® signal between
two different units using the optical input and output connectors.
These connectors are sometimes called → TOSLINK.
The BCA2000 supports both the standard ADAT ® format with
8 channels (at 44.1 or 48 kHz sampling rate) and the S/MUX
format with 4 channels (at 96 kHz sampling rate), both on the
inputs and the outputs via the optical in/out connectors.
A/D converter
An A/D converter transforms an analog audio signal into a
digital signal, for example to enable recording on digital recorders
such as CD/DAT/MD recorders or for recording and/or additional
processing in a computer.
All equipment utilizing digital technology that features standard
analog connectors (i.e. 1/4" or XLR) has an internal A/D → D/A
Converter. These can be synthesizers, digital mixing consoles,
almost all standard delay or multi-effects units or sound cards.
The quality of the converter is often expressed as a combination
of its bit rate and its sampling frequency (e.g. 24-bit/96 kHz).
Generally speaking, the higher these two values, the better the
resolution and therefore the better the audio quality. Older
CD players operate at 16-bit/44.1 kHz. The BCA2000 supports
the current DVD quality standard of 24-bit/96 kHz.
AES/EBU
This professional digital stereo audio format gets its acronym
from the Audio Engineering Society and European Broadcasting
Union. Unlike the consumer format → S/PDIF, AES/EBU signals
are usually transmitted using balanced cables with XLR
connectors, enabling extremely long cable runs without signal
degradation or additional noise. See also → S/PDIF.
Clock
Many digital devices feature → Sync, Clock or Wordclock
connections, usually in the form of coaxial BNC connectors.
When using two or more interconnected digital devices
simultaneously, they must be synchronized to the same clock to
ensure sample rate timing coherence. This synchronization is
performed via the wordclock connector or the digital inputs, i.e.
through the digital audio signal.
Coder/Coding
Synonymous to → Encoder/Encoding.
D/A converter
A D/A converter converts digital audio signals into analog audio
signals. See also → A/D Converter.
Decoder/Decoding
Decoding refers to “deciphering” a digital signal. If you wish to
transmit or store a digital signal in compressed form (condense/
reduce data quantity), you will have to → encode it. To use this
signal later or at a different location, you will have to first decode
the signal. These processes generally occur automatically in
digital audio devices/applications.
DOLBY
® DIGITAL
A more popular name for the → AC-3 surround format.
DTS ®
The “Digital Theater Sound System” is similar in function to the
6-channel surround format → DOLBY ® DIGITAL ( → AC-3).
Because DTS ® utilizes more moderate compression (data
reduction), it sounds somewhat better than AC-3 but requires
more storage space, e.g. on a DVD. This format is also supported
by the BCA2000 on its digital outputs.
Encoder/Encoding
Encoding refers to “encrypting” a digital signal using an encoder.
See → Decoder/Decoding.
Interface
General term referring to connection standards used for digital
data transfer.
The → MIDI interface enables communication between digital
devices; a device with a MIDI interface generally has three MIDI
connectors: MIDI In, Out and Thru. The BCA2000 has all three.
“Audio interface” generally refers to both internal and external
computer sound cards. Internal are those that are built into the
computer (usually PCI cards). External sound cards or audio
interfaces are those that are usually connected to the computer
via → USB or IEE1394 (also known as FireWire ® ), such as the
BCA2000.
LFE
LFE (Low Frequency Effect; sometimes called Low Frequency
Enhanced) refers to the → Subwoofer or sub-bass channel that
reproduces the lowest frequencies of the surround soundtrack
(generally below 80 Hz). This ultra low-frequency information is
usually experienced as sound pressure rather than as identifiable
audio, especially in movie theaters. Even when the
LFE-subwoofer is located front and center, the signal is hard to
locate spatially, since frequencies this low are difficult for the
human ear to process precisely—so instead of actually “hearing”
them, you “feel” them. The “.1” in the nomenclature of various
surround formats, such as 5.1, 6.1 and 7.1, refers to the LFE
channel. See also → Surround.
Limiter
A limiter limits the dynamic spectrum of signal peaks. The
maximal volume of a signal is defined by the → Threshold value.
Limiters are often used to avoid overdriving → A/D Converters,
because this can cause digital distortion, which—unlike slight
analog distortion—is extremely unpleasant, clearly audible and
never desirable. The BCA2000 features an adjustable limiter for
the input sum directly pre- (before) → A/D Converters.
6. CONNECTIONS AND FORMATS