The reports of the demise of power amplifiers have been greatly exaggerated. The recent advent of powered loudspeakers from several leading manufacturers had led many to predict that the golden days of the good ol' power amp were numbered. While powered loudspeakers ideally meet many sound design needs, it's also pretty obvious that they will not be eliminating the more "tried and true" solution any time soon.
In fact, there have been dozens of new amplifier models introduced in just this past year, along with a wide range of enhanced technologies. What's a sound professional to do, given all of these choices?
For starters, we've put together a brief overview of the most recent power amp developments. And as part of this report, we've included website addresses for each company mentioned, so you can do more homework if you choose. Virtually all manufacturers have really taken to the web, understanding that it's a great vehicle to provide easily accessible, detailed product information.
Also during our research for this report, we came across a wide range of solid reference materials. For example, John Roberts of Peavey has put together a summary of current amplifier technologies and topologies ("Class Act: The Pros and Cons of Amplifier Design," www.peavey.com/html/class_act.html). Another is "Anatomy of an Amplifier," (www.qscaudio.com/support/library/papers/papers.htm), written by QSC Audio founder and chief technical officer Pat Quilter. Both of these articles, and several others written or sponsored by manufacturers, are definitely worth a look.
Finally, many of these latest introductions go beyond the scope of amplification, providing enhancements such as built-in digital signal processing, multiple channels, and computer control that can be quite useful in many applications. Note where we quote power ratings, we are talking about number of watts delivered per channel at an 8ohm load, unless otherwise stated. So without further ado, here's a look.
Renkus-Heinz (www.renkus-heinz.com) designs its power amplifiers as components of its fully integrated Reference Point Systems. The P2400, P2700, P2750 and P2950 amplifiers (250W to 750W) are designed to accept plug-in C12 or C22 Series Loudspeaker Specific Controller modules, providing crossover, equalization, phase alignment and limiting protection functions. The controller module monitors the current and voltage output of the amplifier, so all driver protection functions are independent of front-panel input gain adjustments. All signal processing parameters are set by Renkus-Heinz engineering to provide optimum performance.
BGW (www.bgw.com) has debuted the Millennium 3 TMC-2 (330W) and Milennium 2 TMC-2 (220W) include internally mounted cards providing crossover and other adjustable processing functions such as equalization, attenuation, equalization and delay. The Millennium 3 was nominated for a 1998 Mix magazine TEC Award.
JBL (www.jblpro.com) continues to develop modules--offering processing functions--for their premium MPA Series amplifiers (several models ranging from 175W to 820W). The IM10 module supplies 10 crossover frequencies, four transducer delays, and horn correction, all selectable via internal dip switches. XLR output connectors can be programmed to transmit either the high-pass signal or the low-pass signal. The internal crossover to amplifier connection can also be programmed as either high-pass or low-pass using a simple dip switch.
Crown (www.crownintl.com) offers a wide range of cards that plug into the rear of many of its premium amplifiers, providing a host of processing functions. The new USP2 module provides full 24-bit signal processing, including eight independent, fully adjustable filters, second-order parametric EQ, first- through fourth-order crossover, second-order shelving, signal delay, and more. Another feature of the USP2 is an enhanced graphical user interface, which, in tandem with the IQ for Windows v4.0 computer control software, allows for convenient and intuitive graphical editing and setting of all processor parameters.
The recent Electro-Voice (www.electrovoice.com) P1250 (370W) amplifier includes built-in processing utilizing EV's patented Dynamic Signal Processing circuitry to ensure that transient response and phase distortion in loudspeakers are minimized. The processing provides enclosure tuning (12 or 24dB per octave, and adjustment of the "notch" frequency, closely corresponding to the 3dB downpoint of the loudspeaker. Other features include clipping prevention and peak power limiting.
Crest Audio's (www.crestaudio.com) NC-Class input modules provide a selection of in-amplifier signal processing modules for the CK Series. These range from digitally controlled attenuators, analog equalizers, and crossovers through to DSP-based delay, crossover, equalization, and limiting. NC-Class input modules can be configured (with settings stored permanently) via N-Coder (a handheld programming device) or by a laptop running the N-Coder/PC software.
Rane (www.rane.com) was one of the first manufacturers to bring a viable multichannel amplifier to the professional marketplace: the MA 6 (now the MA 6S), offering 100W (per channel), with each pair of channels bridgeable for three higher-powered channels. Recently, the company has introduced the MA 3, a handy little amp offering three channels, each supplying 40W with up to three optional (internal) 70V or 100V distribution transformers.
The brand-new Miles Technology (www.milestech.com) MPR-1K offers six channels (170W each), modular construction allowing a choice of various input configurations and connector options. And each of the six output modules is like a separate power amplifier with a multi-detent gain control, compressor, limiter, low-cut filter, and input selector. Each pair of channels is bridgeable in the compact 2U unit. A half-size version, the MPR-500X, is also now available.
CyberLogic (no website yet) has been on the amp scene for a while now, taking an approach to design best described as "industrial." Also featuring a modular approach, both the NC800 (eight channels) and NC400 (four channels) are ideal for high-end, high-power applications, especially to drive the heavy loads presented by certain larger loudspeakers.
A relative newcomer to the US market, C Audio (www.c-audio.com) offers the Pulse 4x300 four-channel (170W each) amplifier that can also operate as a bridged stereo amp. It also includes a microprocessor controlled power-up feature, and, like the other two new Pulse Series amplifiers (two-channel models), it can be networked via C Audio's CONNECT proprietary network which runs on Category 5 cable. Which leads us to our next category . . .
Crown introduced the first viable method of computer control of power amplifiers to the market almost a decade ago, and the company continues to advance this technology. Of course they're not alone anymore. Getting back to C Audio for a moment, a dedicated interface module interfaces their amplifier network to a PC running Windows 95 or NT. This can then be used to monitor and display input signal voltage, output voltage and current as bargraph meters, as well as monitor the critical protection circuitry. Individual channel level and mute controls and standby power on/off can be controlled remotely using the mouse. Double-clicking any amplifier icon opens up its own control panel with a wide range of controls.
QSC Audio (www.qscaudio.com) continues to expand their QSControl system for controlling and monitoring professional audio equipment over a 10base-t ethernet network. It includes five basic elements: a System Controller (Pentium-based PC), operating software, an ethernet network, QSC CM16 MultiSignal Processors, and QSC amplifiers equipped with a data port. QSControl can be operated with standard System Manager software, or the user can create a custom application for more specific needs. "Open architecture" allows integration of third-party devices using RS-232, RS-485, MIDI, ethernet or other interfaces.
Renkus-Heinz power amplifiers are optionally available with the R-Control Remote System Supervision Network. Based on standards such as Echelon LonWorks and Microsoft Visual Basic, R-Control allows free network topologies using twisted-pair wiring, and networks can be up to 2,700m (8,910') long; longer if readily available LonWorks routers are used. Some capabilities of R-Control include: real-time load monitoring, amp power status, input and output signal levels, power on/off with sequencing, event scheduling, and more.
Crown has recently debuted IQ for Windows v4.0 software, a Windows 95 or Windows NT 4.0 application for operating an IQ System. In addition to control and monitoring of IQ components in a Windows 95/NT environment, it also offers TCP/IP network support and numerous other enhancements. And, it supports the new USP2 module mentioned earlier, as well as all other IQ2 components and original hardware IQ-P.I.P. products. Developed for the 32-bit environment, it also automatically supports new products as they are developed and brought to market, with the simple addition of support files.
Apogee (www.apogeesound.com) now offers the DA Series, employing built-in computer control and a unique electrical topology. Digital control and monitoring is achieved by an on-board microprocessor that measures internal and external conditions such as heat sink temperature and load impedance. Information is displayed on front-panel LCD screens. Additional displays are available to aid in setup and trouble shooting a number of parameters. Diagnostics can be performed in real-time and no external hardware is required for true load impedance measurements. And, DA Series amps can be monitored and controlled when linked to a PC loaded with Apogee's AmpNET software. AmpNET has additional features such as subgrouping, statistical reporting, and remote operation of all functions including sequential power control, gain control, phase state, and more.
Crest NexSys software (and accompanying hardware) have been around for several years, providing a practical and reliable network that allows Crest CK and Professional Series amplifiers to be controlled and monitored via one or more remote PCs. NexSys software version 3.4 features an upgraded interface with new organizational, scheduling, and data manipulation tools. Other features: amplifier channels can be named and treated individually; any number of groups can be created to suit the needs of a system or venue; any combination of amplifier channels, signal processing, or sequential turn-on devices may be grouped together.
Peavey Electronics (www.peavey.com) Architectural Acoustics IA Series amplifiers accommodate a variety of Peavey input and control modules. Some are accessible on the back panel of the amplifier, while others are factory-installed only. One newer module is called AmpWare, which offers Peavey MediaMatrix on-screen monitoring facilities for model IA200, IA400, and IDC150TII models. AmpWare, providing the interface with MediaMatrix, offers fault and clip metering, real-time impedance measurements, and sequential power-up features.
There's likely more than a thousand viable choices for straight-ahead, traditional two-channel power amplification. Suffice to say that whatever your needs, at least one if not several products exist that perfectly fit your specification. We'll kick off this section by focusing on a few of the newest players, particularly in the North American marketplace.
Chevin (www.chevin-research.com) A Series amplifiers employ switching power supplies, but the company notes that their design utilizes a greater number of capacitors for energy storage in comparison to other models. The result is no "running out of steam" complaints common to switching amps. In addition, the company notes that the A Series offers a very high slew rate, similar to that found for high-end recording and live touring applications.
Long known for providing superior studio amplifiers, Hafler (www.hafler.com) has just introduced a new series specifically for commercial (CCA Series) and live sound applications (LSA Series). Both series offer three models--300W, 600W, and 1,200W--based on the same basic amplifier platform. The 300W and 600W units are a new Class G circuitry based around the company's patented Trans.nova platform. With this design, Hafler notes that power is the same regardless of impedance. Meanwhile, the 1,200W version, expected to be available within months, will feature Hafler's own twist on Class D design, which the company claims will allow the amplifier to produce its quoted maximum output level for extremely long periods, rather than just at peak times. Crossovers will be available for the live sound (LSA Series), with digital amplifier control circuitry down the road.
Samson (www.samsontech.com) offers two new workhorse amplifiers, the S1000 (500W per channel at 4ohms) and the S700 (350Wper channel at 4ohms), both with input level controls with 42 precision detents as well as relay-controlled outputs. Parallel outputs allow several of these amplifiers to be linked together.
Yorkville (www.yorkville.com) has continued to foster an ever-growing line, including the new AP6040. Delivering 2,000W per channel at 4ohms, it's particularly good for driving subwoofers. The AP6040 also includes stereo and mono switches, high-pass filter and advanced protection circuitry, as well as a user-defeatable limiter to prevent audible clipping. Another recent addition is the CR5, providing 180W at 8ohms.
The new Carvin (www.carvin.com) DCM2000 is also a good choice for subwoofers, supplying 2,000W, bridged, at 4ohms and 450W per channel at 8ohms. Linear feedback circuits featuring the Motorola(TM) bipolar power device reduces distortion to a near theoretical zero limit. With modular interior construction, the DCM2000 headlines several other DCM amplifiers ideal for a number of professional applications. All offer XLR and 1/4-inch I/O ports and advanced protection circuitry.
The Stage Accompany (www.stageaccompany.com) PPA 1200 is a digitally controlled amplifier providing 350W and equipped with Dynamic Damping Control (DDC). This special circuitry measures the voltage on the loudspeaker terminals by means of extra sensor cables, which is then compared with the amplifier's input signal. If discrepancies are registered, corrections are made, ensuring that the amplifier has almost infinite damping.
Crest Audio continues to expand its impressive line of amplifiers, with the new Pro II Series offering several models ranging from the 4802 Pro II (370W) up to the 8002 Pro II, with an impressive 800W per channel at 8ohms. All of these models include Crest's PowerLok circuit design as well as twin tunnel (rear-to-front) cooling.
QSC Audio has extended its renowned PowerWave switch-mode power supply technology, found in the premium PowerLight line, to two recent lines: PLX and CX Series. Designed to meet the specialized needs of sound contractors, the CX Series includes eight two-channel models (200W to 700W, with five low-impedance models and three 70V models.) One feature of note is Active Inrush Limiting, which eliminates AC in-rush current, removing the need for expensive power sequencers. CX Series amps also include HD15 DataPort connectors for QSControl computer control or signal processing accessories.
Crown's CE Series packs a lot of power into a cost-effective package. Both the CE1000 (275W) and the CE2000 (400W) offer straight-ahead professional features like front-panel detented level controls, useful function indicators, proportional fan-assisted cooling, short circuit protection and more. In addition, a new SST (System Solution Topologies) module which allows the user to customize CE Series amps with features like fixed-point crossover cards.
LAX Sonic Solution (laxaudio.com) has entered the fray with a line of quality professional amplifiers, ranging from the MA 2400 Mk11, supplying 270W to the MA 5200 MK11, which produces 700W. All include forced-air cooling systems with two auto speed-controlled and low noise fans, as well as built in limiter logic output circuitry which generates large voltage swings while avoiding electrical stress on the output stages.
Mackie Designs (www.mackie.com) offers the M1400 (250W) and the M2600 (500W), both ideal for commercial applications. Both include a second-order, 18dB-per-octave Linkwitz-Riley electronic selectable subwoofer crossover. A smaller model, the M800, was just added, equipped with Bessel low-cut, variable filters.
Carver (www.carverpro.com), a long-time player in the amp arena, has introduced the PXm900 (300W), the PXm450 (150W) and the PXm250 (75W). Each includes selectable high-pass filters, clip limiters, and input sensitivity controls, along with over-current, thermal, and DC protection.
Yamaha (www.yamaha.com) offers two new amplifiers with built-in variable subwoofer and low-cut filters. Both the XS250 (170W) and the XS350 (230W) also include rear-mounted, dB-calibrated attenuators as well as variable-speed cooling fans.
The new Electro-Voice Q66 (380W) and Q44 (280W) both offer Neutrik Speakon output connectors along with XLRs. And, they also include rear-mounted level controls and I/O comparator-driven limiters.
Peavey continues to add to its cadre of power solutions, including the CS500A (125W) which can be outfitted with a family of input and output modules. Another amp of note is the DPC1400X, providing 1,400W in bridged-mono mode.
Last, but certainly not least, Sony (www. sony.com/professional) now also offers an amplifier product. The new SRP-P50, delivering 50W, is an ideal problem-solver for low-power applications. The 1U package includes a toroidal transformer and high-supply voltage rejection ratios. Input levels are switchable between 0dB and -10dBu.