C 28:4

The C 28:4 is one of two mid-power, four-channel amplifiers in the C Series family. Attractively packaged in a 2U chassis, it provides 4 × 700 W output into 4 ohm loads.

C Series amplifiers are uniquely capable of adapting to a wide variety of demanding load conditions. Each channel has an individually configurable Voltage Peak Limiter (VPL™), which allows the output to be optimized for any loudspeaker load – whether a single large subwoofer or a series of small 100/70 V loudspeakers. VPL works in combination with adjustable input gain to achieve maximum headroom regardless of input levels or output impedances.

Every C Series is ready for the NomadLink® network right out of the box. With NomadLink, key amplifier parameters are displayed via DeviceControl software, and remote control of channel mutes and power on/off is under network control.

TECHNICAL SPECIFICATIONS

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 all channels driven  16 ohms:  600 W    8 ohms:  700 W    4 ohms:  700 W    2 ohms:  300 W  Hi-Z per ch. (all ch.’s driven):  70 Vrms / 100 V peak 700 W

Max output power bridged  16 ohms:  1400 W    8 ohms:  1200 W    4 ohms:  600 W    2 ohms:  Not recommended (*1)  Bridged per ch.:  140 Vrms / 200 V peak 1400 W

Performance  THD 20 Hz - 20 kHz at 1W:  <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  Common Mode Rejection (CMR):  >50 dB, 20 Hz - 20 kHz  Output impedance @ 100 Hz 30 mOhm

Gain, Sensitivity and Limiters  VPL, selectable per ch (*2):  141, 118, 100, 85, 71, 59, 50, 42 V  VPL, when bridged (*2 -*3):  282, 236, 200, 170, 142, 118, 100, 84 V  Voltage Peak Limiter mode (per ch.):  Hard / Soft  Amplifier gain selectable (all channels) – rear-panel switches (*3):  23, 26, 29, 32, 35, 38, 41, 44 dB  Default gain:  35 dB  Level adjustment (per channel) Front-panel potentiometer, 21 position detented from -inf to

Connectors and Buttons  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 IN and OUT  Intelligent fans (on/off):  Yes, depending on presence of output signal  Power Individual switches on front panel  Cooling:  Two fans, front-rear airflow, temperature controlled speed

Front-panel user interface  Common NomadLink Network; Power Average Limiter (PAL) (*5); 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 V / 65 -135 V (*4)  Minimum power-up voltage, 230 V / 115 V 171 V / 85 V  Power Average Limiter (PAL) (*5):  Yes  Power Factor Correction (PFC):  No  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; C16:4: 15A/NEMA 5-15P

Dimensions - Weight - Finish Dimensions:  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  Approvals CE, ANSI/UL 60065 (ETL), CSA C22.2 NO. 60065, FCC   

Notes *1: Regarding n.r. (not recommended) notes: The amplifier will be fully operational in bridge-mode into 2 ohm and high impedance (Hi-Z) loads, but due to physical constraints in the construction, the max. output power will not be significantly higher than running individual channels and therefore this mode of operation is not recommended. *2: 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. *3: Automatic -6 dB gain compensation when bridging channels. Ch.’s A+B and/or C+D, can be bridged individually. *4: Separate 230 V or 115 V versions available. Not selectable on the amplifier. *5: 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.