Lab.gruppen C 28:4 Instruction manual

An Installation Amplier without Compromise
Installed or on tour, uncompromising quality begins with supe-
rior sound. Over the past decade, the sound of Lab.gruppen ampli-
ers has earned praise from renowned FOH engineers and owners
of the world’s premier sound rental companies. At the core of
the C Series high-power* model’s tight and transparent sound is
patented Class TD technology. As a proprietary implementation of
tracking Class D, Class TD approaches the exceptional efciency of
Class D while retaining the superior sonic quality of the best Class B
output stages.
A Regulated Switch Mode Power Supply (R.SMPS) contributes to
the remarkable efciency of the C Series high-power models, while
at the same time providing stable operation even with wide uctua-
tions in mains voltage. R.SMPS also works in conjunction with Class
TD to give extraordinary power density. More channels with more
power are condensed into a smaller package, allowing C Series
ampliers to minimize rack space requirements and reduce installa-
tion costs.
Extreme power density demands efcient cooling, and here
Lab.gruppen’s Intercooler® proves remarkably effective. Thousands
of small copper cooling ns dissipate heat, and all output devices are
mounted on one row perpendicular to airow for uniform cooling.
C Series ampliers are uniquely capable of adapting to a wide
variety of demanding load conditions. Each channel has an
individually congurable Voltage Peak Limiter (VPL), which allows
the output to be optimized for any loudspeaker load – whether one
massive subwoofer or a series of small 100 V loudspeakers. VPL
works in combination with adjustable input gain to achieve maximum
headroom regardless of input levels or output impedances.
To assure reliability, and minimize service interruptions, C Series
ampliers offer comprehensive warning and protection features.
Whenever faulty wiring, improper use, or extreme ambient tempera-
tures threaten trouble, a C Series amplier gives clear and accurate
warning indications. Protection measures are inserted only when
dangerous thresholds are passed. Conditions are re-checked at
six-second intervals, and normal operation resumes when measure-
ments return to nominal.
Every C Series amplier is ready for the NomadLink® network right
out of the box. With NomadLink®, key amplier parameters are
displayed via DeviceControl software, and remote control of chan-
nel mutes and power on/off is under network control. (NomadLink®
requires the separate NLB 60E NomadLink® Bridge & Network Con-
troller.)
▸Auditoriums
▸Performing Arts Centers
▸Convention Centers
▸Stadiums and Arenas
▸Theme Parks
▸Hotels
▸Houses of Worship
▸Restaurants
▸Clubs
▸Educational Establishments
▸Boardrooms
▸Museums
▸Ofces
▸Shopping Malls
▸Transportation Facilities
Applications
C 28:4
* C Series high-power models are:
C 88:4, C 68:4, C 48:4, C 24:4 and C 16:4
▸Unprecedented power density – Total output of 2800 W
(4 ohms) in a 2U cabinet
▸Four channels – All channels bridgeable for 2- or 3-channel
congurations
▸Lo-Z or Hi-Z (70 V / 100 V) – Selectable per channel, normal or
bridged
▸Patented Class TD amplier topology
▸Voltage Peak Limiter (VPL) – Congurable per channel to
optimize each output for connected loads
▸Phoenix-type input connectors
▸Screw terminal output connectors
▸Comprehensive protection and warning – Excessive output
current, DC, high temperature, very high frequency (VHF), short
circuit, open load, mains fuse protection, and soft start
▸Efcient and uniform Intercooler® cooling
▸NomadLink® network ready
Technical Data
C Series: Dedicated Installation Amplifiers

General
Number of channels 4
Peak total output all channels driven 2800 W
Peak output voltage per channel 141 V
Max. output current per channel 12 Arms
Max. Output Power 16 ohms 8 ohms 4 ohms 2 ohms Hi-Z
Per ch. (all ch.’s driven) 600 W 700 W 700 W 300 W 700 W (70 Vrms / 100 V peak)
Bridged per ch. 1400 W 1200 W 600 W n.r. 1400 W (140 Vrms / 200 V peak)
Performance with Gain: 35 dB and VPL: 100 V
THD 20 Hz - 20 kHz for 1 W <0.1%
THD at 1 kHz and 1 dB below clipping <0.05%
Signal To Noise Ratio >112 dBA
Channel separation (Crosstalk) at 1 kHz >70 dB
Frequency response (1 W into 8 ohms) +0/-3 dB 6.8 Hz - 34 kHz
Input impedance 20 kOhm
Input Common Mode Rejection, CMR 50 dB
Output impedance @ 100 Hz 30 mOhm
Voltage Peak Limiter (VPL), max. peak output
VPL, selectable per ch. 3) 141, 118, 100, 85, 71, 59, 50, 42 V
VPL, when bridged 3) 1) 282, 236, 200, 170, 142, 118, 100, 84 V
Voltage Peak Limiter mode (per ch.) Hard / Soft
Gain and Level
Amplier gain selectable (all channels) 1)
– rear-panel switches 23, 26, 29, 32, 35, 38, 41, 44 dB
Default gain 35 dB
Level adjustment (per ch.) Front-panel potentiometer, 21 position detented from -inf to 0 dB, hidden behind security panel/dust filter grille
Connectors and switches
Input connectors (per ch.) 3-pin Phoenix, electronically balanced
Output connectors (per ch.) Barrier strip 2-pole screw terminals
Output bridge mode A+B and/or C+D, inputs A and C are input source
NomadLink® network On board, 2 x RJ45 connectors
Intelligent fans (on/off) Yes, depending on presence of output signal
Power on/off and Remote enable on/off Individual switches on front-panel
Cooling Two fans, front-to-rear airflow, temperature controlled speed
Front-panel indicators
Common NomadLink® Network; Power Average Limiter (PAL) 2); Power on
Per channel Signal present / High-impedance; -10 dB and -4 dB output signal; Voltage Peak Limiter (VPL); Current Peak Limiter (CPL);
Very High Frequency (VHF); High Temperature; Fault; Mute
Power
Operating voltage, 230 V / 115 V nominal 130 -265 / 65-135 V 4)
Minimum power-up voltage, 230 V / 115 V 171 V / 85 V
Power Average Limiter (PAL) 2) Yes
Soft start / Inrush Current Draw Yes / max. 5 A
Mains connector 230 V CE: 16 A, CEE7; 115 V ETL: 20 A / NEMA 5-20P
Dimensions (W/H/D) W: 483 mm (19”), H: 88 mm (2 U), D: 343 mm (13.5”)
Weight 12 kg (26.4 lbs.)
Finish Black painted steel chassis with gray painted steel front
Approvals CE, ANSI/UL 60065 (ETL), CSA C22.2 NO. 60065, FCC
Note 1): Automatic -6 dB gain compensation when bridging channels. Ch.’s A+B and/or C+D, can be bridged individually.
Note 2): PAL can reduce the maximum output power to keep the power supply operating safely, and/or to prevent excessive current draw tripping the mains breaker.
Refer to Operation Manual.
Note 3): For sine waves, peak voltage output values translate to Vrms with the formula V/1.41 = Vrms. E.g. 100 V peak equals app. 70 Vrms.
Hence, outputs can be set for high-impedance loads without requiring a transformer.
Note 4): Separate 230 V or 115 V versions available. Not selectable on the amplifier.
All specifications are subject to change without notice.
Item no. TDS-C284_V5
L a b . g r u p p e n a b ▸ S w e d e n
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Specifications C 28:4