Power AmplifiersTraditionally, 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 a 4/08/2010 8:00 AM Eastern
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.
Apr 8, 2010 12:00 PM, By Bennett Liles
The Crown Audio CDi series is designed especially for installation, and the CDi 6000 can output on barrier strips 3000W into each of two channels with a 2Ω load, 2000W per channel with a 70V system, and 5000W into a 140V system in bridged mono mode. The CDi 6000 also features proportional fan-speed cooling; output short and thermal protection circuits; and onboard DSP including crossovers, EQ filters, delay, and output limiting.
Designed for permanent installations using 70V/100V loudspeaker systems, the AXYS PB800 from Duran Audio is composed of eight separate AB class power amplifiers and a two-in, eight-out digital-signal-processing unit. The amplifier features soft-knee over current protection, and a low-power standby switch mode allows networked shutdown of the main supply. The 32-bit floating-point DSP includes attenuate, delay, equalization, filters, compression, and limiting on the individual channels.
For mobile and club sound systems, the Dynacord SL 2400 is the most powerful amplifier in the SL series with 2400W into each channel at 2Ω and 3600W at 4Ω in bridged mono mode. The unit incorporates protection for thermal, overload, short circuit, HF, and DC faults along with a patented LPN filter for switchable phase response correction on the loudspeaker load. The SL2400 has a 1kHz referenced gain of 32dB and a maximum input level of +21dB.
Intended for continuous duty cycle applications in paging and sound reinforcement, the CAZ2500 from EAW provides a continuous power level at 8Ω of 575W per channel into its two channels and 1500W in bridged mode. With a 4Ω load, the amplifier pushes 750W per channel and 2500W in bridged mode. It features a switchable low-cut filter at 30Hz and a switchable limiter. The front panel includes gain knobs along with signal presence and gain overload LEDs.
The PA4150L from Electro-Voice is made for multichannel applications using a minimum of rack space with four channels in a 2RU frame. The rear panel features marked level controls along with Phoenix connectors on all inputs and outputs. Front-panel LEDs indicate signal presence, 0dB, and limiting, and each channel includes a selectable 50Hz/300Hz high-pass filter. The unit provides 160W into each of the four channels.
Extron Electronics’ answer for high-power multichannel sound in a 1RU case is the XPA 2004, an Energy Star-qualified amplifier that puts 200W at 4Ω into each of its four channels. A class-D design with a 100dB signal-to-noise ratio, the XPA 2004 is convection-cooled for quiet operation. It goes into standby mode using less than 1W after 1 hour of no signal, and it has protection circuits for limiting, thermal overload, shorts, and DC.
The solution for multichannel amplification in a 2RU enclosure from Lab.gruppen is the C 20:8X, with continuous output power of 250W per channel into outputs of 70V, 4Ω, 8Ω, and 16Ω. Each channel is individually configurable for a specific application or load condition. The unit’s gain may be configured in 4-channel groups along with a 35Hz high-pass filter, and the Voltage Peak Limiter (VPL) feature permits each channel to be configured for the reactive characteristics of the connected load.
The FRS2800 from Mackie is at the top of the FRS line, with 2800W continuous power in mono bridged mode into 4Ω. Like the others in the line, it features a front-panel, six-segment LED meter for each channel along with a defeatable clip limiter and short, thermal, over-current, and under-impedance protection. The multispeed cooling fans change speed automatically according to operating temperature, and there is a third Neutrik Speakon connector carrying the bridged mono output.
Apr 8, 2010 12:00 PM, By Bennett Liles
The Nady Systems SPA 2400 provides a range of running mode options including a user-defeatable clip limiter, continuously variable-speed fan, switchable 30Hz low-cut filter, and XLR and TRS input connections, along with dual-channel, parallel input, and bridged mono operating selection. Outputs feature both binding post and Neutrik Speakon connections, and there is a ground-lift switch. The unit puts 750W into each of two channels at 4Ω and 2400W into 4Ω in bridged mono mode.
A resonant switch-mode power supply, two channels with independent 100Hz crossovers, and high-speed class-D topology typify the IPR series amplifiers from Peavey. The IPR DSP 6000 puts 200W RMS into each channel at 4Ω, and it includes built-in 32-point digital signal processing, program-specific EQ presets, crossover and stereo/mono operation with setup wizard, and lockable security settings that are adjusted using a front-panel LCD screen. Protection circuitry includes Peavey’s DDT loudspeaker protection with multipoint clip sampling along with DC, temperature, signal, and active safeguards.
Introduced at InfoComm 09, the Duecanali5204 from Powersoft is an installation version of the K3 amplifier. The class-D unit puts 1400W into an 8Ω load and 2600W into 4Ω. In bridged mono mode, the output is 3900W into 8Ω and 4800W into 4Ω. It also incorporates the patented Powersoft automatic voltage-selection feature. Integrated DSP provides up to 16 EQ filters per channel and a delay in each channel of up to 2 seconds.
For applications requiring maximum channel density in minimum space, the QSC CX168 has eight channels and is equipped with QSC’s PowerWave switching power supply technology to run with less noise. Safety circuits include protection from DC, infrasonic, thermal overload, and short-circuit faults. QSControl, QSC’s audio networking system, can be used through four HD-15 data ports to control the CX168’s gain levels and to monitor clipping, thermal status, and other system parameters.
When a higher degree of remote control is needed in a multichannel amplifier, the MA 4 from Rane can provide four areas of sound control with 100W into each with terminals for remote level control and built-in load monitoring, adjustable high-pass filters, fault reporting, and redundancy switching. Optional 70V/100V transformers are available, and there is adjustable dynamics control for temperature, sensitivity setting, and load impedance.
The SX3200 power amp from Samson is a 2-channel unit delivering 800W at 8Ω and 1100W at 4Ω, and in bridged mono mode, it provides 2200W into an 8Ω load. LED indicators display power levels for each channel, and combination input connectors allow for the use of either 1/4in. or XLR connectors. Protection circuits avoid overheating or damage from bad connections and prevent thumps in the loudspeakers when the amp is powered up. Two temperature-sensitive, variable-speed fans provide cooling.
For seven-zone sound control through a 70V or 25V loudspeaker system, the Speco Technologies PL200M 160W commercial amplifier features front-panel zonal on/off buttons and source selection buttons with the ability to play different sources in different zones at the same time via one unit. There is also a preamp input and auxiliary and booster outputs, three combination 1/4in./XLR mic/line/phantom inputs, and two RCA auxiliary inputs. The output terminals include 4Ω, 8Ω, and 16Ω loudspeaker terminals and a music-on-hold feature.
At the other end of the power scale and offering compact, low-cost push for sound is the CVA-50-1 from Stewart Audio. The ace for this model is getting power into small places, and the unit’s plenum rating and remote control feature are key to this. Using Signal Sense Power Technology, the amp is only powered when there is an audio signal on the input. The unit delivers 100Hz to 20kHz sound with a signal-to-noise ratio better than 90dB. The level control is screwdriver-adjustable, and the front panel includes LED indicators for power, signal presence, and clipping.
Top of the Juice line of power amps from Tapco, the J∙2500 delivers 575W into each of its two channels in an 8Ω load and up to 2500W into 4Ω in bridged mono mode. It offers switchable low-cut filters and switchable limiters on each channel. Detented rotary gain controls are calibrated in decibels, and the front panel includes signal presence, power, and overload-warning LEDs. Cooling is handled by variable-speed fans with back-to-front airflow.
The TOA DA-550F is an installation amplifier delivering 550W into each of four channels at 4Ω and 350W per channel into an 8Ω load. The channels can be bridged, enabling an output of 1100W into each of two channels at 8Ω. The input signal to channel 1 can be routed to all channels with individual gain control on each channel output. All channels offer input/output status LED indication, and input connections feature both removable terminal blocks and XLR terminals.
Most powerful of the Yamaha TXn series amplifiers, the TX6n offers 2-channel analog input and includes AES/EBU signal capability with its digital input MY card feature, which supports a variety of other audio formats. Through a connected computer running the Amp Editor software application, control and monitoring functions—including switching the amplifier’s on/standby and mute status along with considerable DSP features—can be done in addition to handling these functions on the unit’s front panel. The TX6n delivers 1100W per channel into 8Ω and up to 5980W into 4Ω in bridged mono mode.