Amplifier Buying Guide

Amplifiers are the engine in any sound system, without them you will not hear a thing. So what does an amplifier do exactly? An amplifier takes the low level signal from a source, such as a CD player or tape deck, and amplifies it to a very high level capable of driving a loudspeaker.

There are three basic types of amplifiers; a pre-amplifier, a power amplifier and an integrated amplifier. Let's look at what each one does...

The Pre-Amplifier

A pre-amplifier does two things; Firstly it is a switching unit that connects to all of your source components such as your CD player, Tape Deck, Set-Top-Box, Television, or even a Turntable. The pre-amplifier allows you to select which source you want to listen to. 

After selecting your source, the pre-amplifier uses a gain stage to control the overall volume you will hear through your speakers, but it needs some help to do that, namely a power amplifier. In simple terms the pre-amplifier drives a power amplifier.

The Power Amplifier

A power amplifier is a simple beast, it takes the signal from the pre-amplifier and amplifies it to levels that can be heard through your speakers. While the pre-amplifier takes a line level signal and amplifies it to a level that a power amplifier requires on input, the power amplifier increases the signal again to drive your loudspeakers.

Think of the pre-amplifier as the finesse, and the power amplifier as the grunt. And, at this point it is pretty clear that if you have a pre-amplfier, you have to have a power amplifier, one will not work without the other.

The Integrated Amplifier

An integrated amplifier is essentially a pre-amplfier and power amplifier in a single chassis. They share both the chassis and the power supply and can provide equal quality for a lower entry price. For years this industry has touted separates (pre and power) as the only way to go for high-end audio, but integrated amplifiers have come along way and rival many separates for both quality of sound and grunt.

The disadvantage of course is that you can not upgrade your power amplifier if you go out and buy a less efficient speaker for example, you have to change your entire amplification setup, separates allow you to upgrade one or the other at will.

So, Separates or Integrated?

For me personally I am more than happy with the quality of the modern day integrated amplifiers. Companies such as Aaron and Calyx have superb offerings, and all but the absolute audiophile tragics would not be happy with their performance.

But, if you want absolutely huge power, then separates will be your only choice as few integrates offer more than 200 watts per channel. This is when Bel Canto's 1000watt monoblock amplifiers are your best bet, budget permitting of course...

What to Consider when buying an amplifier

The obvious thing to keep in mind when selecting an amplifier, is the power output of the amplifier. Will it be enough to drive your loudspeakers to the levels you like to listen at, without damaging your speakers? And remember, too much power is better than too little! (See our Speaker Buyers Guide for more on this)

Impedance is a major specification to check. If your speakers are 8 ohms, then you should be fine as that presents a relatively easy load for most amplifiers. If however your speakers are 4 ohms, then you should check if the impedance 'curve' dips down below 3 ohms at any point.

The reason for this, is that very low impedance loads are difficult for all but the very best amplifiers, so matching your amplifier to the speakers is very important here. Also, the type of amplifier Class is important.

Now without going into depth on amplifier designs, there are three main classes; Class A, Class B and Class D. Class A is a very inefficient form of amplification but it offers a very musical sound. Class B is a little more efficient, and Class D is extremely efficient.

To put the efficiency into perspective, for every 100 watts of power an amplifier draws out of your wall socket, a Class A amplifier will output around 30 watts of power. A Class B amplifier around 40-45 watts of power, and a Class D amplifier over 90 watts of power. So what happens to the extra power? It is dissipated in heat, which is why Class A amplifiers get extremely hot, many of them too hot to touch.

Some amplifiers use what is called Class A/B, and these amplifiers operate in Class A up to a certain power output, and then switch to Class B mode for efficiency. Our range of Aaron amplifiers do this, and offer all the sweetness you could expect of Class A, but they never get hot at all.

Class D is what is taking the high-end world by storm, because it offers extreme efficiency, small size and little or no heat. Companies like Bel Canto and Calyx offer Class D amplifiers that provide extremely good sound quality, and are certainly the way forward in audio.

However, Class D has one problem; they do not like impedance loads below 3 ohms, so you need to check for speakers impedance curve to be sure it does not dip this low. If it does, then look at a Class B or Class A/B amplifier. Again, our range of Aaron amplifiers are perfect for these types of speakers, in fact they are stable down to 1 ohm loads which very very few amplifiers can handle.