How do you use it?īefore you start, make sure the amplifier has enough ventilation: if the slots are obstructed, or the amplifier is put in a small cupboard with the door shut, there is a danger it will overheat. Most PA amplifiers have two channels (Left & Right, A & B, or 1 & 2), providing independent level control over the signal on each. For this reason, power amplifiers in PA systems are almost always fitted with cooling fans and ventilation slots.

Typically the work is shared by a number of transistors (a dozen or more in most cases), and these can get very warm when the amplifier is running at full power. Most modern PA amplifiers use transistors to convert the signal from low to high power. Its main purpose is to reproduce a low-power signal at high power.

It converts a low-voltage, high-impedance waveform into a high-voltage, low-impedance waveform. A power amplifier takes a line-level signal and reproduces it in a form that will drive a loudspeaker. To distinguish it from other kinds of amplifier (such as preamplifiers or line amplifiers), the main amplifiers are often described as ‘power amplifiers’. Technically, any device that applies gain (even negative gain) to a signal is an amplifier. A few manufacturers have tried 1U models, but you won't find many of these in professional touring PA systems. Most modern amps are in 2U boxes unless they are very high-powered (over 1kW per channel into 4 Ohms), in which case the box may be 3U or even 4U. What it isĪ PA amplifier usually takes the form of a 19″ rack-mounted box. Crown's xps and xti ranges, and d&b's D6 and D12 - incorporate functions that have historically been the province of Crossovers and Controllers). It doesn't look very exciting, and usually has fewer knobs, lights or buttons than very basic effects or processors (although some - e.g. An amplifier is the workhorse of a PA system.

Power amplifier pa