Guitarists have been trying for the past few years to condense their onstage contraptions. One way to achieve this is to purchase an amplifier which will serve the purpose of Special effects devices like sustain, fuzz, and other distorting feedback mechanisms. If you want that English flash rock ’n roll hoochie koo, getting an amplifier with enough meat to feed an army is a way out. But the problem becomes "how much meat does it take to feed an army?”

Many moons ago when Randy California was playing lead for Spirit, he figured out a relatively cheap way of getting endless sustain and distortion. He used an old Silvertone electric, which had contact pickups — you backof-the-shop type people might like to know that pickups are really “electromechanical transducers” — but anyway, contact pickups, known as “cheapos” by guitar players, are simply microphone elements placed under the guitar’s strings, and they tend to pick up any surface vibration caused by the strings (clothing rubbing on the surface of the guitar, for example). But due to the high gain required to make this type of pickup function, it is ideal for feedback and distortion and weird mike squeals even through a low powered amplifier, thus feeding an army on soybeans. Today, most pickups are of the magnetic breed, as opposed to this contact type system.

Since most guitars do incorporate this type pickup, a powerful amp becomes more of a necessity for putting out a powerhouse Sound. And when you go shopping for a powerhouse, blow’em-down type output amp to produce the effects of special effects devices, the next problem becomes what ratings to look for.

Because there are several ways to measure wattage, an amp rated at 250 watts could possibly have little more than 100 watts of actual output, when rated by another measurement. That is, if you are a shuck and jive manufacturer who wants all the kiddies to buy a dog amp, you could rate the output of your amp using the peak music power system. An amp with 100 watts of peak music power usually has around 50 watts RMS actual output. Thus you’ve got an amp you can call a 100 watt-er, when in actuality, it’s only 50. It’s a good game to play on the unsuspecting, novice guitar player.

The main ways used to measure wattage in today’s music industry are RMS (sine wave power), peak power, and music power (EIA or IHF). Out of these three, RMS comes the closest to the true measure of the amp’s ability to perform, since peak power and music power measurements are more flexible and have too much latitude in the measuring process.

If you’re confounded by the RMS rating of an amp, the next logical step would be to use the famous ’ol side-byside measurement of an amp’s output. While this is a little primitive, it usually gets the job done, and the decision made. This is particularly good since there is one flaw inherent in all three methods of measuring wattage — all three systems fail to take into consideration the loudspeaker’s efficiency. A 200 watt amp may not be as loud as an amp with 100 watts and an efficient speaker. Thus, the move is on for an acoustical sound level rating which would incorporate a combined evaluation of the amp’s electrical output and the speaker’s efficiency. Until that day does come, the ’ol side-by-side is definitely where your ear should be at when looking for flash-loud sound.

The side-by-side method consists of simply getting a long instrument cord and standing back away from the amps as you blurp out their loudest sounds with guitar in hand. The best way is to begin playing at a lower volume and gradually crank on it, doing the same with the other amp. Don’t pay too much attention to the numbers on the volume knobs, since most amps generate about three-quarters of their high output sound when they’re turned up only half-way. It’s also handy to have a friend along who can play the knobs while you give your undivided attention to the amp’s output and sound qualities.

Feedback is a circle of sound which begins when the guitar’s strings are played; it is then picked up by the pickup, and put into the amp. Then it comes out of the amp’s speaker (s), reaches the guitar, vibrates the strings, and keeps them vibrating until another string is played or you cover the strings with your hand (palm it). If you want to test the amp’s feedback qualities, you’ll have to stand a little closer to the amp and turn up the volume. If you start by facing your guitar directly into the speaker cabinet about a foot away and with the amp on a fairly low volume, you can gradually raise the volume until feedback sets in. Then you’ll have a good idea about where feedback occurs. Since feedback produced through a magnetic pickup usually requires a good deal of power output, you can use a feedback itself as a power rating. Unless some anti-feedback features are incorporated into either the guitar or the amp, this can be a good system of measurement. Remember, though, that feedback is a building process and many times if you don’t give the guitar and amp a chance to build up the volume (automatic) and create the whining noise, you won’t have a good indication of what are the feedback qualities of that amp.