Receivers. Amplifiers, Preamplifiers - Their Functions
When beginning the process of starting a home theatre, sifting through all the jargon associated with the A.V industry could prove to be a daunting task, and one of the questions asked by the public is whether they should buy a receiver, preamp or amplifier without fully understanding what purpose they actually serve.
The critical difference between the three is based on their functions. Receiver connects input and output devices, whereas an amplifier boosts a signal so it can be played through speakers. A preamp, however, boosts a microphone signal to the level that it can be boosted through an amp.
A.V Receivers: The AV receiver is one of the major components in creating a home theatre system, because it acts as the central hub of your home theatre and fulfills a number of functions.
It’s the device that connects everything together, it’s where you hook up your input devices, such as DVD players, game consoles, etc. and your output devices, which would be your speakers, T.V’s and projectors. This being said, having so many devices connected to one device would require that device to be easy to use.
Another function of a receiver is that it gives you master control over your audio settings. Along with volume, a receiver would allow you to control the EQ, surround sound modes and such.
While these are the main functions of a receiver, they often have a number of other functions that are of varying benefit in a home theatre. These include:
- Decoding digital surround sound formats from the input source so they can be properly played on speakers.
- Works as the central interface for your home theatre (possibly through a mobile app). Many also have dedicated LED screens so you can adjust settings.
Amplifiers: Simply put, an amplifier is a device that turns a low voltage signal powerful enough to power speakers. However, the power of an amplifier will vary depending on its purpose.
The second function of an amplifier is that it allows you to collect multiple signals before converting them to a line-level signal. Line-level signal refers to the signal that’s sent to the speakers, and so is the level that all input signals need to be at.
In short, a receiver is an amplifier but not all amplifiers are receivers. The amp’s job is to
Boost signals so they have enough gain to play through speakers. Anything else is considered an extra function and is more likely to be found in a receiver than an amplifier.
Amplifiers can be split into two categories:
- Power Amplifier. This is simply an amplifier on its own that boosts input signals for speakers.
- Integrated Amplifier. This amp also contains a preamp, meaning it can boost signals and add enough gain to be played through speakers.
Amps are usually required if you have speakers that require a lot of power, or plan on using more speakers than your receiver can handle. Connecting power-hungry speakers to a receiver can cause it to overheat or break down, so this is when an amp comes in handy.
The bottom line is that if you've had success finding a receiver that has enough power to handle the high power system you may own, there may not be a need to have an amp as well.
Preamps: A preamp is one of the more ambiguous parts of a home theatre setup. At the most basic level, a preamp takes particularly weak input signals and boosts them so they’re in line with the other signals being processed in the amp.
The best example to explain this is recording equipment. A microphone has such a weak signal that it’s referred to as mic-level, which is considerably weaker than instrument-level signals.
All of these signals need to be boosted to a line-level signal, which is then boosted by the amp and sent out to speakers. Basically a preamp boosts the signal to the right level for the amp.
Hence, when choosing a preamp, it must work in line with your amplifier. The devices must have similar power levels so they don’t interfere or create unnecessary feedback or signal distortion.
Along with boosting weaker signals, a preamp has to modify the sound quality in line with boosting the volume. Without a level of audio processing, the signal received by the amplifier would be far too muddy and contain too much distortion.
Preamps aren’t really something we need to concentrate on much in home theatres. They are much more common in the recording world, which uses more devices like microphones.
In conclusion the most sensible option you could go for in a home theatre, particularly if you are looking for the best sound quality and if you're new to the AV scene is to invest in an AV receiver.
If you have some knowledge of AV equipment, going for an amplifier system would be alright, this is because amplifiers require more manual setup, along with more pieces of equipment.
Conversely, switching to a separate system can make quite a good project for the home theatre pro.