Let’s face it, power amps are the Rodney Dangerfield of pro audio equipment. They’re not particularly interesting to look at, they all sound great (or we get rid of ’em!), and they usually get placed away from all the other equipment. Do they get any respect? Not until they fail—at which point, they command all the attention. Isn’t it interesting how these black (okay, sometimes they come in different colors) boxes can bring the entire show/studio to its knees when they decide not to cooperate? Of course not! The point is, we depend on these vital components far more than we care to admit.

Now that we are thinking about power amps, how are they progressing from a technological perspective? What are we likely to see in future product designs? Considering their level of importance to virtually every studio, contractor installation, touring act and theater, it makes sense to consider what changes may be headed our way. During the course of my interviews with the key manufacturers in this area, several important trends in power amp design emerged. Whether you’re searching for an amp that is lighter, more efficient, or has a greater level of interactivity with other components in your production environment, there are some interesting developments worth examining.

ACTIVE DEVELOPMENTS IN POWER AMPS

Where is amplifier technology headed? Active loudspeakers are certainly a good place to begin. While the term “powered monitors” used to be a dirty word, much has changed recently and all indicators point toward numerous such products in the future.

Bill Calma, chief operating officer at Tannoy/TGI North America Inc., offered this perspective: “The biggest trend will be active loudspeakers, due to the reduced size and weight of switching power supplies and the latest amplification circuitry. While powered loudspeakers have been around for some time, the industry is on the verge of a proliferation of products. This is the result of significant advances in electroacoustics and DSP processing.”

There’s good reason for this development. This design approach is intended to give the end-user greater control of the overall system. Since many power amps have already reached the point where they deliver more power than the speakers can handle, the focus needs to shift toward more efficient systems design—that system, of course, being the combination of power amp and speakers.

David Solari, president of CyberLogic, concurs. “More and more, we see power amplifiers being integrated into loudspeakers—either as in-cabinet designs or dedicated ground support systems whereby the amp is specifically tailored to a specific speaker cabinet. Rather than trying to build amps that ‘do all things for all people,’ this trend will result in power amps being built and configured specifically for a particular task—resulting in improved cost efficiency for the manufacturer and better value for the customer.”

Switching power supplies are also a hot topic with manufacturers these days. Since nobody wants to drag heavy equipment around, a power amp’s weight is a major consideration for touring acts. Switching power supplies both reduce the amplifier’s weight and increase its efficiency.

Although they involve greater expense and more parts, switching power supplies offer distinct advantages. For example, it is easier to regulate the operation of the high-frequency transistors to compensate for variations in the AC voltage and load currents—thus improving power supply regulation. This, in turn, results in more consistent amplifier performance.

Stephen Morris, product line manager at Crown International, considers switching power supplies to be a critical issue for amplifier development. “I believe a large percentage of the focus for manufacturers will be on the power supply portion of the amplifier,” he says. “The market is now asking for lighter-weight amps that can also provide appropriate power under normal operating conditions, but with reduced current draw. One of the quickest ways to achieve this is to provide a switching power supply. This design requires much lighter and smaller magnetics, with the key benefit being significantly reduced weight.”

When a product is rated to meet a particular power specification relative to its impedance, the rating is based on the assumption that the unit will draw a designated amount of current. Now manufacturers are required to provide more efficient designs by reducing the amount of current the amplifier draws—largely because European countries have particularly stringent standards in this area. The issue is known as power factor correction (PFC)—with the crux of the matter revolving around the need to draw less power from the wall to get the same amount of power from the amplifier.

QSC’s PowerLight 9.0PFC, released in 1998, was the first to amp include Power Factor Correction in its power supply. PFC can reduce the amplifier’s average AC current consumption by as much as 40%, and peak requirements by as much as 80%.

REMOTE OPERATION

While a select number of currently available products can be remotely controlled, efforts are underway to improve connectivity via the Internet as well as local-area networks (LANs). The ability to monitor the diagnostics of equipment and provide updates will become even more important than they are now.

A major advancement in this area has been the development of CobraNet technology. This combination of firmware and a network protocol licensed by Peak Audio allows the transmission of multichannel digital audio signals across an otherwise standard Ethernet network. However, for the purposes of supplying data signals only in a networked system, standard 10Mbit Ethernet can handle hundreds of amplifier control channels with near-instantaneous response, at a fraction of the bandwidth required for multichannel digital audio. Although CobraNet has the capablility of combining audio and control data on a single physical network, existing control systems do not currently  use CobraNet for control and monitoring. Thus far, however, this aspect of CobraNet technology has yet to be realized, though key manufacturers are committed to improving the situation.

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Reprinted with permission from Mix Magazine, May 2000
© 2000, Intertec Publishing, A Primedia Company All Rights Reserved