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Just as with speakers, every hifi system requires an amplifier. You 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 a pair of speakers. A source unit, such as a CD player, only produces a low voltage/current signel. This low voltage signal is nowhere near strong enough to power a set of speakers; this, of course, is the role of the amplifier, to add the required voltage to this signal. It's fair to say that an 'amp' is the 'heart' or 'engine' of a system, and will impact largely on the quality of the sound produced by a hifi system. Alongside the sound signal an amplifier can juice up, there are other factors to consider, one of which is the inputs supported. Not all amplifier's support record players, now that CD players are the most common source unit. Whether you're after a laid back or an assertive amplifier, you should narrow your decision down to the build quality, musical talent and useful features found upon an amplifier. Types of Amplifiers Integrated - Combines a preamplifier and power amplifier in one box. The purpose of separating a power and pre amplifier, is that the power amplifier can produce some sonic signals which can impact upon the delicate components of a preamplifier. Preamplifier - As the name would suggest, a preamp controls the signal produced by a source unit and routes the signal to a power amp. Some source units, like a CD player, 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. Anatomy To begin with, the construction of amps included vacuum tubes. While it's still possible to purchase amplifiers made with vacuum 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 required, they use low voltage, and produce a high current. All of which is the opposite of tube amps, which many audiophiles swear by. The positive attritributes of a vacuum tube amp is the robust handling of electrical voltage, the buffer capabilities of the transformer, and the 'unique' sound produced. 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 up to 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 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. It's interesting to note that a 200 watt amplifier is not twice as powerful as a 100 watt amplifier. For an amplifier to be twice as powerful as a 100 watt amplifier, it would need to produce 1000 watts. This is all somewhat confusing and misleading to a novice consumer of hifi equipment. The power of an amplifer has nothing to do with it's quality. Key features to look for - Watts per channel - An above average amp will produce between 65 - 85 watts of output; which does not signify a powerhouse amp, but should create enough grunt to power speakers to a good 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 - Inputs for a tuner, CD player etc. - Parallel phono connectors- Enables a user to daisy chain amps and any preamplifiers. - A phonostage - Which means the amplifier supports a turntable, ideally it should be accurate and have plenty of space. - Headphone input - Self explanatory. - Uprated power supply - For integrated amps with a built-in preamp, the poweramp section provides a mono module for the right and left speakers.
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Hifi Amplifier
