Submitted for your approval...a trio of worthy power amps, all in competition for your hard-won bucks. Regardless of your persuasion, whether it be heavy metal, hard rock, folk rock, hard folk, punk, power pop, or light-heavyweight void, you all have at least one thing in common: you want people to hear you. So at some point along the way, things such as these must be dealt with. Assuming that the more you know about the game, the better you play, take a look at a few of the least glamorous but most important aspects of music that you will someday have to reckon with.

The new Model 600 from BGW Systems represents something of a departure from earlier models by BGW, primarily because it doesn’t cost as much as one would expect it to, and because it isn’t as elaborate an amp as BGW has produced in the past. This is perhaps because there are other amps, newer on the market, that have been successful in capturing a share of the market with a no-frills approach.

However, the basic solid construction and reliable performance that have characterized BGW to date are still a part of the new amp, The Model 600 delivers a strong 175 watts of power per channel (it is stereo with mono option—in the mono mode the amp yields 500 watts) under an 8-ohrri load. Drop it down to 4 ohms and the power is increased to 250 watts, with no more than 0,15% total harmonic distortion. In simpler terms, the sucker is plenty loud and it don’t make no noise that it ain’t supposed to!

. As I said, the basics of the BGW design, the 'things that make these amps so outstanding; are left intact on the Model 600. Things such as the high-speed Op-amp front end and redundant output stages that utilize ten 150-watt transistors each are a part of the BGW design philosophy. In fact, at a glance the amp looks much like the older amps in the line: only a few of the “convenience” features have been eliminated from the Model 600.

The 600 also has the massive heat sink assemblies that other BGW amps have; these devices help keep the amp cool during operation. One thing that has always impressed me about these amps is that the protection circuitry is such that it is virtually impossible to How up speakers, no matter how hard you. try! About the worst thing that can happen, except under the most extreme conditions (the kind usually brought on by human inadequacy!), is that the amp will get hot and temporarily shut itself off. When that happens, you simply wait for it to cool off, then turn it back on again—no real harm done.

BGW has always had a good reputation for performance—with the introduction of the Model 600, maybe their reputation concerning high prices will change for the better.

On the other hand, if you’ve got some cash that’s burning a hole in your pocket and you want to go out and-buy the “fully-loaded-factory-airwhite-sidewall-sunroof -AC -full-power-and-air” version of a power amp, the engineers at Yamaha have just the thing for you. It is the new M-2, a stereo power amp rated at 240 watts per channel.

Modern amplifier design has gotten to the point that undesirable factors such as THD (Total Harmbnic Distortion) have been reduced to extremely low levels in most pro quality amps. But Yamaha has an amp that has such low THD rating that they had to come up with a new measuring system, using a computer and a spectrum analyzer, just to measure the THD! The M-2 has a factory rating of 0.005% THD at 8 ohms. Factory engineers can provide you with a detailed explanation of how this is achieved, but unless you are an electronics expert yourself, it probably wouldn’t make a bit of sense to you anyway. Let’s just say that, according to information supplied by the manufacturer, the amp is virtually free from harmonic distortion.

Of course, THD is only one kind of distortion. Amplifiers have several kinds. Other forms of voodoo—crossover distortion, switching distortion and notch distortion—are all eliminated by the M-2's superior design.

The M-2 has two separate constant-voltage power supplies, a 3-stage power amp output and two independent protection circuits. A power subcurrent limiter protects the transistors from overload damage caused by shorted speaker terminals or impedance irregularities; in addition, a cutoff relay protects the speaker system from damage. A DC voltage of plus or minus one volt is all it takes to activate the relay. Like the BGW, the M-2 won’t blow your speakers. Another feature of the M-2 is the muting circuit. This withholds signals from the speakers for five seconds after the amp is activated, which prevents shock to speakers, the kind of shock that usually won’t blow the speakers right away, but is definitely not good for them and can be damaging in the long run.

Instead of VU meters on the front panel, the M-2 uses an LED (light-emitting diode; i.e., a little tiny light) to indicate the output level of each channel. The LED display is easier to read, especially from a distance and/or in the dark comers of nightclubs, and the lights change from green to red when the amp begins to clip.

The Yamaha M-2 is definitely a top-of-the-line product, and it might be unfair to compare it with the other two amps mentioned here on a strict one-to-one design basis. Besides, there is a vast difference in price among the three amps, which must be considered too. The^>oint is not to draw direct comparisons between the three, but rather to familiarize you with some of the options available in power amps. In the end it will be up to you, your group and your bank account to decide what to buy.

Before you make the decision to go with one of the more established names in high quality audio; it might be wise to consider a relative newcomer —the Peavey CS-800. This amp delivers 280 watts RMS into an 8-ohm load with less than 0.05% THD. Like the other two amps, the CS-800 has a speaker protection circuit and a “crowbar circuit,” which instantaneously halts the output to the speakers in the event of an amplifier failure. Also, the CS-800-is subject to temporary shutdown if the amp is overloaded for a long time, thereby protecting the rest of the system.

Usually when speakers and drivers are blown, it is because the power amp is being overdriven, thereby delivering a clipped waveform (a square wave) to the speaker system. Because of the high DC content and high harmonic content of square waves, they are very destructive to speakers.

The CS-800 combats the problem of clipping with a compression circuit called the DDT (Distortion Detection Technique). The DDT circuit acts as a monitor within the amplifier which electronically senses the clipped waveforms and compensates for the presence. Also, an indicator light on the front panel (one for each channel) indicates that the amp is clipping. It is a very useful feature, but the DDT compression circuit can be overridden if the user so desires, simply by pulling out the push/pull volume knob on each channel. Although the option is there, it would be best to use the DDT circuit all the time during live performance. When used as a home stereo amp, the compression might not be necessary; however, in that situation one would have to be very careful to select the proper speaker system, because that much power per channel (400 watts RMS into 4 ohms with both channels driven) will trash most home speakers easily.

A rear panel inspection of the CS-800 reveals some clever thinking on the (part of Peavey designers. By using an optional jumper plug (which is supplied with each unit), the balanced XLR input is rendered for use as an unbalanced input, so the user has the option of running high impedance or low impedance inputs^ Another jumperplug in the electronic crossover accessory socket makes the amplifier function as a full range amp in the normal mode; however, Vi” phone' plugs on each channel make possible the use of an external crossover. Therefore, the amp works well by itself, or with an electronic crossover and other power amps in a biamp situation. A two-speed fan keeps the amp cool during periods of long operation.

Performance capabilities, price, features, options—all these factors must be considered when choosing among, any power amps. Naturally, each manufacturer feels that the amp,they rhake is the best. Statistics can be impressively presented (and are) in each case. The potential buyer has to try to figure out, based on his own knowledge and experience, the advice of others he trusts, and in-the-field testing, which amp is the best for him. The main thing to remember is not to be influenced by what so-and-so group uses, or by a,fancy name and a high price tag, but to rely on good judgement in a dollar-per-watt-ofperformance evaluation of the product;