Picking a excellent stereo amplifier for your speakers is not a trivial task. You want to ensure that your amp matches your speakers. I will clarify some basic amplifier terms and give some pointers to help you pick the best amplifier.
Audio amplifiers come in all different shapes and sizes. They use different technologies and have many technical specs. By following some simple guidelines, you will be able to pick the model that best fits your application and budget.
One vital criterion is the size of the amplifier. You can buy models which can fill half a room. In contrast, some of the latest miniature amplifier models are no larger than a deck of cards. Many amplifiers are rack sized. This allows them to be stacked on top of your other audio equipment.
There are some core amplifier technologies available. One technology is called “solid-state”. Solid-state amps now account for the majority of audio amplifiers. In the past, tube amplifiers have been well loved. Even today tube amplifiers are still available. Unfortunately, tube amplifiers have honestly high audio distortion which describes how much the audio signal is degraded by the amplifier.
Tube amps will have audio distortion of up to 10%. Solid state amplifiers will have lower audio distortion depending on the amplifier technology that is used. The most traditional amps use a “Class-A” and “Class-AB” technology. These amplifiers are also called “analog amplifiers”. While amplifiers using these technologies typically have low audio distortion, power efficiency is only 10% to 30%. Power efficiency describes how much of the electrical power is used to amplify the audio as opposed to being wasted as heat. Amplifiers with low power efficiency will require honestly large heat sinks because most of the power is radiated.
In contrast, “Class-D” amplifiers which are also called “digital amplifiers” offer a power efficiency of typically 80 to 90%. This allows the amplifier and power supply to be made much smaller than analog amplifiers. Due to the switching output stage, digital amplifiers typically have higher harmonic distortion than analog amplifiers. But, some of the latest models are able to reduce distortion to 0.05% and less by employing a feedback mechanism.
The amplifier should be able to deliver enough output power to sufficiently drive your speakers which will depend not only on how much power your speakers can handle but also on the size of your listening environment. Speaker power handling is given as peak power which describes the maximum amount of power during small bursts while average power refers to how much power the speakers can handle continuously.
If you have a honestly small listening environment then 20 to 50 Watts of power should be plenty even though your speaker may be rated for 100 Watts or more. Note though that speakers differ in their sensitivity. Typically a low-impedance speaker will be simpler to drive to high volume than a high-impedance speaker. Check your amplifier manual to ensure that your amp can drive your speaker impedance.
Two other vital parameters to look at when picking an amplifier are signal-to-noise ratio and frequency response. Signal-to-noise ratio describes how much noise the amplifier will introduce and should be at least 100 dB for a high-quality amplifier. The frequency response shows which audio frequency range the amplifier covers and should be at least 20 Hz to 20 kHz.
Gunter Fellbaum has been designing audio and electronic products for over a decade. You can get further information about t-amp models as well as power amplifier products from Amphony’s website.
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