Amplifiers

Tech » Audio » Amplifiers » Buying Guide

Amplifiers are generally the boring part of your sound system. But they are also the most important part of it. Without an amplifier you're not going to get very far. Many speakers come with amplifiers built in but if you want to be able to mix and match and generally have a cool set-up, getting a stand alone one is the way to go.

Power output is the most important feature of the amp but it's a long way from being the only important feature. Impedance is also important. These two together determine what your power output will be. You want a higher number when it comes to power and a lower number for impedance.

Most amps will have different power outputs at different impedances. Speakers are commonly 8 ohms impedance but top range and professional ones will often be 4 ohms and some may even be 2 ohms. Then again some may be 16 ohms. You need to make sure you know what speakers you are going to be plugging it to the amp before you decide which amp you buy (or, you could pick your amp and then pick your speakers – the point is, you can't make both decisions independently).

What connections the amplifier will take is also important. Generally you will want balanced XLR, 1/2” jack and RCA inputs though few amps will come with all three. It depends what you are going to be connecting it to. Home stereo equipment will probably have an RCA (phono) outputs. A good quality mixer however will have XLR outputs. You also need to consider outputs. This will usually be speakon outputs as these are now the standard connector for speakers though lower range speakers may use 1/2" jacks.

In terms of quality you can also look at the frequency range an the signal to noise ratio. The signal to noise ratio wants to be as low as possible to maintain high sound quality and the frequency range should be fairly standard unless you are looking at amps designed for a specific purpose.

Some amplifiers come with a ground lift switch to help problems if you are getting background noise. Also if you are designing a powerful sound system it is useful to have an amp which can be run in bridge mode so you can channel the entire amp's output to one channel. If you plan to use the amp in a tough environment like a club you should also consider how the amp keeps itself cool.