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

i n t e r n a t i o n a L c o n t a c t ▸ i n f o @ L a b g r u p p e n . c o m | u S & c a n a d a c o n t a c t ▸ i n f o @ t c g - a m e r i c a S . c o m