Welcome to 'Amplifier for me'

Introduction

Just as with speakers, every hifi system needs an amplifier. Some may ask why?, what's so important about an amplifier. Well, you simply cannot listen to stereo music without it being amplified and passed onto your speakers. Otherwise your speakers will not understand what's being sent to it. It's fair to say that an 'amp' is the 'heart' or 'engine' of a system, and will have a major say in the quality of the sound produced by a hifi.

Alongside the sound quality an amplifier can produce, there are other factors to consider. The inputs an amp can offer is also another essential element. Depending on the source unit (cd player etc) you intend to use, recording devices, and speakers, you will need to consider the inputs you will need. Finally, there is the power output to consider, this will dictate if your amp can control your speakers properly.

Whether your after a laid back or assertive amplifier, you should narrow your decision down to the build quality, musical talent and useful features.

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Integrated - combines a preamplifier and amplifier in one box.

Preamplifier - originally they were simple a pickup unit with inputs, they have since been modified to amplify signals of a low-level and provide voltage gain. However, many source units like CD players are producing a flat line signal, so a preamp is not always necessary.

Power - The term may be incorrect in a technically sense. However, it usually refers to an amplifier that takes the signal from a preamp or source unit, increases it's current, watts or 'power' and makes it suitable for being passed onto the speakers.

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Anatomy

Initially the construction of amps included vacuum tubes, whilst it's still possible to purchase amplifiers made with tubes, most manufacturers have transferred to using transistors. The advantage of a design using transistors is the lower amount of heat they generate, no transformers are needed, the low voltage they use and the high current they produce. All of which is the opposite of tube amps, however, many audiophiles still swear by tube amplifiers. Some positives of the tube vacuum include their robust handling of electrical voltage, the buffer capabilities of a transformer and their 'unique' sound.

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Power

All amplifiers have a 'power' grading, which is in watts, or for load impedance's in ohms. Whatever the power grading is, manufacturers will give the maximum watts the amp can provide. In reality, the amp will provide wattage from zero upto it's maximum level.

Amplifiers use alot of energy from the mains socket, which is needed to give a weak signal enough watts to power a pair of loudspeakers. Therefore, amplifiers by their nature produce alot of heat. The more efficient they are, the more energy they will put to good use, and the less heat they will create.

It's also true to say that the more watts an amp can create, the more power and heat they can potentially generate. Therefore, it's vital for a powerful amp to have a good airflow and a shutdown procedure for the occurrence of overheating.

Key features to look for

- Watts per channel. An above average amp will produce around 65 - 85 watts output, which does not signify a powerhouse amp, but should create enough grunt to power speakers to a high level.

- Frequency Response. Indicates the accuracy of an amp to reproduce a music recording. A response spectrum of 1 Hz - 65 kHz should ensure a high level of accuracy.

- Harmonic Distortion. In a perfect world an amplifier would pass on a pure signal with no harmonics whatsoever. Most amps are rated for 'Total Harmonic Distortion' or THD, less than 0.05% is coveted.

- Plenty of line level inputs, e.g. for tuner, CD player etc.

- Parallel phono connectors, enables you daisy chain amps and any preamplifiers.

- A phonostage, ideally should be accurate and have plenty of space.

- Headphone input.

- For integrated amps with a built-in preamp, an uprated power supply. And for the poweramp section a mono module for the right and left speakers.

- Provides enough details for complex classical and jazz pieces, the deep bass of rap, and the delicate emotion of a ballad.