Lab.gruppen LAB 1200C User manual

FOUR CHANNEL
POWER AMPLIFIER
1200
C
FEATURES
◆ 4x370 W into 8 Ω
4x380 W into 4 Ω
at clip level with four
channels driven
◆ Compact design, 2 U high
(88 mm)
◆ Low weight
◆ MLS switch offers full power
in 8 or 4 ohms without
increased power losses
◆ Electronically balanced
inputs
◆ LED indicators show output
voltage and headroom
◆ Independent protection
circuitry
◆ ALS
TM
short circuit protection
manages long-term short-
circuit operations
◆ VHF protection
◆ DC protection
◆ Output cooled by Intercooler
®
◆ Two proportional speed fans
◆ Clip limiter
LAB. GRUPPEN’s LAB 1200C is a four-
channel, 370 watts per channel,
light-weight power amplifier,
designed for 19” rack mounting.
The LAB 1200C gives the opportunity
of use in several applications, such as; in
multi-channel monitor systems, four-
channel reproduction, and compact am-
plification in active 2-, 3-, and 4-way
systems.
The LAB 1200C gives the possibility
to bridge connect one or two of the two
pair of channels (channel A and B and/
or channel C and D). These bridge
mode combinations solve most of the
problems concerning different imped-
ance’s and maximum power handing of
loudspeakers.
The switch-mode power supply is the
modern solution of the weight and size
problem. With switch technology oper-
ating at a high frequency, it is possible to
use ferrite transformers instead of heavy
iron transformers and large electrolytic
capacitors.
Switch-mode technology has been ap-
plied in power supplies in TV-sets during
the latest 30 years. But in the LAB 1200C
the power capacitivity is 10 times larger.
We have designed the LAB 1200C to
obtain the same characteristics as a con-
ventional power supply. Thanks to the
switch-mode power supply it is easy to
get the DC-rail voltage stabilised. This is
made by controlling the magnetic ener-
gy in the ferrite transformer with a
pulse width processor and magnetic
“Flux Sense” windings.
Twenty-four 250 watt bipolar power
transistors constitute the output stages,
which are totally complimentary. The
power transistors are cooled by a solid
copper cooler, called Intercooler®, origi-
nally designed for our LAB 1300 power
amplifier. LAB. GRUPPEN’s specially
designed thermal feedback circuit pro-
tects against thermal breakdown.
The LAB 1200C is completely short-
circuit protected . The LAB 1200C is
equipped with LAB. GRUPPEN’s Adap-
tive Limiting SystemTM short circuit
protection, which permits very high
peak-currents, but still holds the transis-
tors within the so-called “Safe Opera-
tion Area” at the present operating volt-
age. This makes it possible to run
loudspeakers with impedance varia-
tions, which are considerably lower than
the lowest permitted impedance of the
power amplifier.
Six more protection circuits, which
are separate for each channel, protect
the LAB 1200C and the loudspeakers:
Two DC protections; one DC current
limitation protection, supplemented
with fuses on each DC voltage power
supply rail; and one DC voltage protec-
tion of Crowbar type, which works by
short-circuiting the output to protect
the load.
Thermal protection; prevents the
LAB 1200C from being overheated. The
protection indicators on the front panel
are switched on, as a warning, before the
protection occurs.
VHF protection (Very High Frequen-
cy); protects the loudspeakers against
strong non-musical signals above the
audible area.
Clip limiter; prevents severely clipped
waveforms from reaching the loud-
speakers, but maintains full peak power.
AC protection; shuts down the out-
puts if the line voltage is outside the
operating voltage of the LAB 1200C.
All electronics are mounted on six
modules. The modules are easily accessi-
ble for replacement or repair, etc.

SPECIFICATION
Lab.gruppen AB, Gullregnsvägen 16, SE-434 44 Kungsbacka, Sweden.
Tel. [phone]. Fax [phone]. www.labgruppen.se
1200C
MAX OUTPUT POWER
1)
16 Ωfour channels
8 Ωfour channels
4 Ωtwo channels 2)
4 Ωfour channels
2 Ωtwo channels 2)
16 Ωbridged stereo
8 Ωbridged stereo
MLS
Switch
8
8
8
4
4
8
4
FTC
20 Hz-20 kHz
at 0.1% THD
190 W
350 W
650 W
340 W
580 W
700 W
680 W
EIA
1 kHz
at Clip (1% THD)
200 W
370 W
700 W
380 W
640 W
740 W
760 W
IHF
Peak Power
20 msburst
210 W
380 W
720 W
400 W
720 W
760 W
780 W
SPEAKER PROTECTION
Each channel is fuse protected on the positive and negative power supply rails. Electronic short-circuit protection with a progressive
characteristic. The output power is turned off at shorted output. The power amplifier can be run into short-circuits for a long time
without damage, and is open circuit and mismatch proof.
DISTORTION
THD 20 Hz-20 kHz and 1 W-240 W 4 ohms 0.07 %
THD at 1kHz and 300W 4 ohms 0.01 %
DIM 30 at 150 W 4 ohms 0.008 %
CCIF (13 and 14 kHz) at 100 W 4 ohms 0.008 %
SMPTE (60 Hz and 7 kHz) at 150 W 4 ohms 0.01 %
POWER BANDWIDTH
3)
5 Hz-110 kHz
Slew rate 60 V/µs
OUTPUT IMPEDANCE 1 kHz 0.03 ohm
HUM AND NOISE below max power <- 105 dBA
CHANNEL SEPARATION 1 kHz 80 dB
10 kHz 70 dB
PHASE AND DELAY
Deviation from perfect delay 150 Hz-20 kHz ± 1°
Total delay input to output at 4 ohms 3.5 µs
INPUTS
Sensitivity for full output into 4 ohms 1.3 Vrms
Gain 29 dB
Impedance 20 kohms, balanced
Common mode rejection at 1 kHz 50 dB
FRONT PANEL
Gain controls (4) Channel A - B, C - D
Output displays (4) red + (4 ( 2)green LED´s Fast peak - slow release
Protect indicator (4) yellow LED´s 80° C at heatzink or > 20 kHz at full power or shorted output.
On indicators (4) green LED´s DC rail voltage for channel A, B, C and D
REAR PANEL
Input connectors (4) XLR type 3 pin female (pin 2+).
Output connectors (2) Neutric 4-pole speakon connectors (pin 1+ output, A, C)
Switches: (pin 2+ output, B, D)
Link A+B / B+C / C+D
Polarity B Reverse polarity of channel B
Polarity D Reverse polarity of channel D
Clip limiter A, B, C and D On - Off
MLS 4 or 8 ohms
POWER Option
Operation voltage 130 V - 280 V AC 65 V -135 V AC
Minimum start voltage 190 V AC 95 V AC
Full output power 180 V - 260 V AC 90 V - 130 V AC
Peak inrush current 4.5 A
OVERALL DIMENSIONS
mm (inch) 483 (19”) W
x 88 (3.5”) H
x 335 (13.2”) D
WEIGHT 8.7 kg (19 lbs)
APPROVALS CE Emission EN 55 103-1, E3
Immunity EN 55 103-2, E3, with S/N below 1% at normal
operation level 4)
Safety EN 60 065, class I
LAB. GRUPPEN reserve the right to alter functions or specifications without prior notice.
1) Specifications measured with 230 V regulated AC
2) Continuous power, two channels driven or peak power four chan-
nels driven. (Thermal protection may occur at high continuous power).
3) The VHF-protection turns off the channel for frequencies above 20 kHz
at full power.
4) Normal operation level 1/8 of full power or -9dB below clip point.