Behringer BCA2000 - Manual (Page 21)

21
B-CONTROL AUDIO BCA2000
MIDI
The Musical Instruments Digital Interface is a generic, non-
manufacturer-specific standard that enables communication
between electronic music instruments. If you connect the MIDI
Out (output) of the first device to the MIDI In (input) of the second
device, the second device can be “remotely controlled” by the
first device. If device 1 is a MIDI keyboard and device 2 a keyless
tone generator (“MIDI expander”, sound module or similar), you
can “play” device 2 from your MIDI keyboard, implement program
changes or influence various sound parameters in real time.
Important! MIDI merely “controls” devices; absolutely no audio
data is transmitted! The above example will actually let you hear
the MIDI expander controlled by the MIDI keyboard only if the
audio outputs of your MIDI expander are also connected to a
mixing console and/or amplifier and loudspeakers, or if
headphones are connected to the expander’s headphone output.
Noise Gate
A noise gate suppresses noise and interference during signal
pauses by muting the signal path when the input signal falls
below a predetermined → Threshold value. A noise gate is
generally used to eliminate noise and crosstalk. Also known as
gate, suppressor or noise suppressor, while the terms expander
and downward expander refer to the type of circuitry or method
of suppression used.
The BCA2000 features a noise gate for the analog input sum,
located directly pre- → Limiter and pre- → A/D-Converters.
Phono
Also known as RCA, these unbalanced connections for analog
audio are primarily found in hi-fi applications but are also
commonly used for the digital S/PDIF interface. The BCA2000
features both, and they are labeled correspondingly.
Plug-In
A plug-in is an addition to a full-fledged computer program;
these additions “embed” themselves into the main application
and augment its functionality. Plug-ins are not stand-alone
programs; they always need a “host” application to work.
Some of the more well-known plug-in formats in computer
audio technology are Direct X and VST interfaces. If an audio
application supports, for example, the VST format, additional
effects or virtual tone generators can be integrated into the main
program and be controlled, adjusted, played and recorded within
the host application.
RCA
Another term for → Phono connectors.
Sample Rate
The sample rate is often considered an important quality criterion
for certain audio standards or → A/D converters. For example,
CDs use a sample rate of 44.1 kHz. This means that an audio
signal is digitally sampled 44,100 times per second. With the
→ ADAT ® format, 48 kHz is common, and with DVDs, 96 kHz is
the norm.
The BCA2000 supports all of these standard sample rates. If
you wish to produce a CD, it is recommended to select 44.1 kHz
for the entire production (all digital devices and all tracks in the
audio software). This will prevent possible quality loss due to
subsequent sample rate conversions.
With → A/D converters, the sample rate needs to be roughly
twice the frequency of the audio signal that is being digitalized.
This means: With a sample rate of 44.1 Hz, the highest audio
frequency that is accurately reproduced is about 22,000 Hz.
This frequency lies above the highest frequency audible by a
healthy human ear.
Sampling frequency
See → Sample Rate
S/MUX
S/MUX (Sample Multiplexing) is a special → ADAT ® format that
supports a → Sample Rate of 96 kHz, with the limitation that only
4 audio channels can be transmitted instead of the usual 8. See
also → ADAT ® . The BCA2000 supports this format as well as
the standard → ADAT ® format on the optical digital inputs and
outputs.
S/PDIF
The Sony/Philips Digital Interface Format is a consumer
standard for transmitting digital audio. This unbalanced interface
utilizes → RCA or optical → TOSLINK connections.
From the point of view of data structure, this signal is very
similar to the professional → AES/EBU format. Therefore, you
can transmit AES/EBU and S/PDIF signals using the same cables
and connectors, although AES/EBU is generally transmitted via
XLR connectors and balanced cables, enabling extremely long
cable runs without signal degradation or interference. S/PDIF is
usually used for data transmission over shorter distances with
unbalanced cables.
The BCA2000 features both RCA and optical connectors; the
control panel software provided with the unit allows you to
select either the AES/EBU or the S/PDIF format.
Subwoofer
Large bass loudspeaker designed to produce extremely low
frequencies (generally between 20 and 150 Hz), which cannot
be spatially located by the human ear and are thus usually
experienced as sound pressure rather than distinguishable audio
signals. For this reason, subwoofers are often used in mono.
Subwoofers are commonly used in large P.A. systems (concerts
etc.) as well as in movie theaters etc.; also used in home
→ Surround systems. See also → LFE.
Surround
Since the introduction of DVD video, surround sound
(three-dimensional room sound) has continuously gained in popularity
and importance. Surround audio formats have been around since
the 1970s, for example the failed attempt at launching quadraphonic
sound, or the Dolby ® Surround format that was introduced in the
movie ‘Star Wars’ in 1978. Nowadays, → AC-3 ( → DOLBY ® DIGITAL)
and → DTS ® have established themselves as the prevalent standards.
In this context, the 5.1 format is generally considered to be the
standard: 5 full-range loudspeakers plus one → Subwoofer. The 5
loudspeakers are divided into Left Front (generally called ‘L’), Right
Front (‘R’), Center (‘C’, mostly for dialog) as well as Left Rear or
Left Surround, (‘LS’) and Right Rear or Right Surround, (‘RS’).
The BCA2000 can play back all common surround formats via
its digital outputs, provided that correspondingly encoded signals
are available on your computer.
Sync
Abbreviation for “Synchronization”. Connectors labeled “Sync”
often have the same function as → Clock or Wordclock.
Threshold
The level above or under which a signal processor becomes
active, i.e. a compressor, → Limiter or → Noise Gate.
TOSLINK
Term describing the optical (consumer) connector used for
transmission of digital audio signals such as → S/PDIF or
→ ADAT ® . A fiber-optic cable transmits the data between two
TOSLINK connectors. The BCA2000 has one TOSLINK or optical
input and output connector each.
USB
The Universal Serial Bus is the current standard for connecting
peripheral devices such as scanners, printers or audio
→ Interfaces to a computer.
USB 1.1:
Until recently, there was only the so-called USB 1.1 standard,
whose maximal data transmission rate was 12 Mbps (megabits
per second). This places certain restrictions on audio applications.
For example, a maximum of eight signals can be transmitted
simultaneously with a maximum resolution of 24 bits and 48 kHz
→ Sample Rate: two inputs and six outputs or four inputs and
four outputs. At 24 bit/96 kHz only stereo recording/playback is
possible. An eight-channel transmission in one direction (to or
from a computer) would also be problematic.
6. CONNECTIONS AND FORMATS