Apr 8, 2010 12:00 PM, By Bennett Liles
Traditionally, one of the most vulnerable points in any sound system has been the power amplifier. Operating at high temperatures for long periods, the power amp has always been a target for shorts and overloads, but the technology advances in the past few years have met the challenge and created a new breed of power amps offering a greater degree of local and remote control, more durable and dependable components, and better design for safety and high-quality sound. With a variety of applications, the models seen here are typical of this trend.
The Alesis RA500 uses advanced convection cooling techniques for quiet operation and provides 250W RMS power per channel with a 4Ω load and 500W RMS at 8Ω in bridged mono mode. The unit exhibits an audio frequency response of 10Hz to 70kHz +0 -3dB with a damping factor of 200. With the input control at maximum, the input sensitivity is +4dBu (1.23V) for rated output and the maximum input level is +26dBu.
The SRA-4150 from Ashly Audio has a fanless design for low-noise operation offering four channels with 150W per channel at 4Ω. The SRA line features Euroblock input connections and screw terminal outputs, signal presence and clip alert status LEDs, and individual channel audio-level controls. Amps in the STA line also have remote on/off ability and an adjustable turn on delay of up to 8 seconds. There are two choices of input sensitivity selectable by a switch on the rear panel.
For medium-sized clubs or mobile PA systems, the Europower EP4000 from Behringer features individual channel gain controls, signal and clip LEDs, selectable low-frequency filters, Toshiba/Fairchild power transistors, independent DC and thermal overload protection, and a back-to-front ventilation system with air filter. The 2-channel unit delivers 2000W into each channel at 2Ω, 1400W per channel at 4Ω, and 4000W in mono bridged mode. The inputs include both XLR and TRS jacks, and the outputs have Speakon-compatible connections.
The new AudiaFusion from Biamp Systems is a multichannel amplifier and more with open architecture DSP, 16x16 CobraNet I/O, and dual CobraNet ports. The unit is TCP/IP network-controllable and customizable with eight amplification modules per frame and either 70V/100V or low-impedance outputs. Front-panel LEDs show signal presence, peak level, clipping, heat sink temperature fault, amplifier failure, and fan stuck-rotor fault.
Capable of driving a variety of loudspeaker systems, the Bogen HTA250A has 4Ω, 8Ω, 25V, and 70V outputs and delivers 250W continuous power with 20Hz to 20kHz frequency response ±1dB. The amplifier employs MOSFET circuitry to provide high efficiency, less heat, and more power with less weight. The rear panel includes a level-setting control, AC line fuse, and auxiliary AC receptacle along with the input connections, and the front panel has an illuminated power switch and an overload/short warning LED that resets when the trouble has been fixed.
The Camco Q-Power 10 is a class-D amplifier delivering 2500W RMS into each of four channels with a 4Ω load in a 2RU chassis. The unit offers switchable limiters for channels A/B and C/D along with automatic voltage selection for 120V or 230V operation. There is also protection on inrush current, power on/off transients, and output DC along with temperature monitoring of heat sinks and transformers. Output connections include two 4-pole Speakon terminals and a covered barrier strip.
With a switched-rail class-H output stage and triple compound design, the Crest Audio CC 5500 is one of three CC Series amplifiers based on Crest’s Pro 200 Series technology. The CC 5500 features a toroidal power transformer; magnetic circuit breaker power switch; mode-selector switch for stereo, mono, or bridged operation; variable-speed fan; and balanced XLR/TRS combination jacks. It can deliver 1550W into each channel at 8Ω and 5550W in bridged mono mode.
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