Lab.gruppen C Series C 28 4 Specifications
Architect’s and Engineer’s Specifications
C Series: Dedicated Installation Amplifiers
C 28:4
Overview: Channel Modes and Network
The power amplifier shall provide four discrete channels of
amplification. Rear-panel switches shall enable bridging of adjacent
channels to allow reconfiguration as a 2- or 3-channel amplifier, with
increased power output available through the bridged channels.
Each channel (discrete or bridged) shall be capable of independently
driving either low impedanceor high impedance (70 Vrms /100 V
peak) loads. The amplifier shall employ a proprietary tracking Class
D output circuit topology. The amplifier shall be equipped with sen-
sing and communication circuits to allow comprehensive remote
control and monitoring functions via a separate network bridge. The
proprietary control and monitoring network shall employ TCP/IP
protocols, use Cat-5 cable for interconnection, and allow remote con-
trol from either the network bridge front-panel or from an external PC
using proprietary software.
Power Output and Performance
Maximum total output of all four channels shall be 2800 watts. In dis-
crete four-channel mode, each amplifier channel shall deliver maxi-
mum continuous output power as follows: 600 watts into 16 ohms,
700 watts into 8 ohms; 700 watts into 4 ohms; 300 watts into 2
ohms; or 700 watts into a high impedance (70 Vrms /100 V peak) load.
Maximum output voltage per channel shall be 100 Vrms; maximum
output current per channel shall be 12 Arms. In bridged mode, each
bridged channel shall deliver maximum continuous output power
as follows: 1400 watts into 16 ohms; 1200 watts into 8 ohms; 600
watts into 4 ohms; or 1400 watts into a high impedance (140 Vrms
/ 200 V peak) load.
Default amplifier gain shall be 35 dB, with rear-panel adjustment
from 23 - 44 dB in 3 dB increments, selectable for each channel. For
bridged channels, the amplifier shall automatically compensate –6
dB gain internally to maintain operation of all channels at selected
gain.
The amplifier shall exhibit the following performance parameters
with gain set at 35 dB and VPL (Voltage Peak Limiter) at 141 V:
Frequency response shall be 6.8 Hz to 34 kHz, +0/-3 dB at 1 watt
into an 8 ohm load; channel separation shall be greater than 70 dB;
and signal-to-noise ratio shall be 112 dBA. THD at 1 watt, 20 Hz – 20
kHz, shall be less than 0.1%; THD at 1 kHz shall be no more than
0.05% at 1 dB below clipping.
A voltage peak limiter shall limit peak output as determined by rear-
panel switches. In discrete four channel mode, peak voltage shall be
selectable in eights steps across a range of 141 V to 42 V. In bridged
mode, peak voltage shall be selectable in eight steps from 282 V to
84 V. The voltage limiter mode shall be selectable for either hard or
soft limiting characteristics.
Connectors, Controls, and Indicators
The following connectors and controls shall be provided on the
REAR-PANEL of the amplifier. The four input connectors shall be
electronically balanced, 3-pin Phoenix connectors. The four output
connectors shall be 2-pole barrier strip screw connectors. A group
of seven DIP-switches shall determine the following: Amplifier gain
(23 dB to 44 dB in 3 dB increments); option active; fan masked;
and bridged mode selection for channel pairs. A group of sixteen
DIP-switches shall determine Voltage Peak Limiter values for each
channel, selectable in eight steps, and Hard or Soft limiting char-
acteristic. Two RJ45 connectors shall be provided for input and
output of the control/monitoring network signals. An LED adjacent
to the RJ45 connectors shall indicate active or inactive status of the
network.
The following indicators and controls shall be provided on the
FRONT-PANEL of the amplifier. Four level control potentiometers,
one for each channel, shall be provided beneath a front-panel secu-
rity cover; potentiometers shall be detented and provide attenuation
from 0 dB to minus infinity in 21 steps. Individual switches shall be
provided for power on/off and remote power on/off enabling. Front-
panel LED indicators shall be provided to show status of power on/
off (green), network connection (blue), Power Average Limiter (red),
and option card active (yellow). Additional LED indicators shall be
provided to show the status of the following for each channel: signal
present and high-impedance warning (green/red), signal present at
–10 dB and –4 dB (2 x green), voltage peak limiter clipping (red),
current peak limiter (CPL) active (orange), very high frequency (VHF)
warning (yellow), high temperature warning (yellow flashing), and
high temperature fault with output muted (yellow constant). Mute
shall be indicated by illumination of both the temperature and VHF
LEDs on a channel; fault shall be indicated by illumination of both the
CPL and VHF LEDs on a channel.
Power Supply, Protection, and Cooling
The power supply shall be a regulated switch mode type. The
amplifier shall operate from AC line sources of either 230 V nominal
or 115 V nominal, with operating ranges of 130 – 265 V and 65 – 135
V at line frequencies of 50 Hz or 60 Hz. Minimum power-up voltages
are 171 V (230 V nominal) and 85 V (115 V nominal). A soft start
circuit shall limit current inrush at power-up to 5 A. The amplifier
shall be equipped with a PAL™ (Power Average Limiter) circuit to
prevent excessive current draw. The amplifier shall be cooled by two
temperature-controlled, variable-speed fans, with air flow from
front-to-back. Adaptive fan on/off function shall be dependent on
presence of an output signal.
Physical
The amplifier shall be 483 mm (19 in.) wide, 88 mm (3.5 in. / 2 U)
high, and 343 mm (13.5 in.) deep. The weight shall be 12 kg (26.4
lbs). The cabinet shall be black painted steel with a grey painted steel
front-panel.
The amplifier shall be approved for use as specified by CE, ANSI/UL,
ETL and the FCC. The amplifier shall be the Lab.gruppen C 28:4.
Item no. AES-C284_V4
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