To help you pick a stereo amplifier model, I will explain the term "signal-to-noise ratio" that is commonly utilized in order to describe the performance of audio amplifiers.
Once you have narrowed down your search by looking at several fundamental criteria, including the amount of output power, the size of the amplifier and the price, you are going to still have quite a few models to choose from. Now it is time to take a look at a few of the technical specifications in more detail. An important parameter of power amplifiers is the signal-to-noise ratio. To put it simply, the signal-to-noise ratio shows how much hum or hiss the amp is going to add to the audio signal. This ratio is commonly shown in decibel or "db" for short.
You can make a simple comparison of the amp noise by short circuiting the amp input, setting the gain to maximum and listening to a loudspeaker attached to the amp. By and large you will hear two components. The first is hissing. In addition, you will frequently hear a hum at 50 or 60 Hz. Both of these are components which are produced by the amplifier itself. Then compare several amps according to the following rule: the smaller the amount of noise, the higher the noise performance of the amp. Though, keep in mind that you should put all amps to amplify by the same amount to compare several amplifiers.
If you prefer an amp with a small level of hissing, you may look at the signal-to-noise ratio figure of the specification sheet. Most makers are going to publish this number. amplifiers with a large signal-to-noise ratio are going to output a small amount of static. One of the reasons why amplifiers generate noise is the fact that they utilize elements such as transistors as well as resistors which by nature create noise. Typically the components which are located at the input stage of an amp will contribute most to the overall noise. Consequently makers typically will pick low-noise components when developing the amplifier input stage.
Many of modern amplifiers are based on a digital switching architecture. They are referred to as "class-D" or "class-T" amps. Switching amplifiers include a power stage that is always switched at a frequency of approximately 400 kHz. This switching noise may result in a certain level of loudspeaker distortion yet is frequently not included in the the signal-to-noise ratio which merely considers noise between 20 Hz and 20 kHz.
The most common method for measuring the signal-to-noise ratio is to set the amplifier to a gain which allows the maximum output swing. Subsequently a test signal is input to the amp. The frequency of this signal is typically 1 kHz. The amplitude of this signal is 60 dB below the full scale signal. After that the noise-floor energy is measured in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.
Frequently the signal-to-noise ratio is shown in a more subjective method as "dbA" or "A weighted". This technique was designed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. Then again, signals under 50 Hz and above 13 kHz are hardly heard. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is typically higher than the unweighted signal-to-noise ratio.
Once you have narrowed down your search by looking at several fundamental criteria, including the amount of output power, the size of the amplifier and the price, you are going to still have quite a few models to choose from. Now it is time to take a look at a few of the technical specifications in more detail. An important parameter of power amplifiers is the signal-to-noise ratio. To put it simply, the signal-to-noise ratio shows how much hum or hiss the amp is going to add to the audio signal. This ratio is commonly shown in decibel or "db" for short.
You can make a simple comparison of the amp noise by short circuiting the amp input, setting the gain to maximum and listening to a loudspeaker attached to the amp. By and large you will hear two components. The first is hissing. In addition, you will frequently hear a hum at 50 or 60 Hz. Both of these are components which are produced by the amplifier itself. Then compare several amps according to the following rule: the smaller the amount of noise, the higher the noise performance of the amp. Though, keep in mind that you should put all amps to amplify by the same amount to compare several amplifiers.
If you prefer an amp with a small level of hissing, you may look at the signal-to-noise ratio figure of the specification sheet. Most makers are going to publish this number. amplifiers with a large signal-to-noise ratio are going to output a small amount of static. One of the reasons why amplifiers generate noise is the fact that they utilize elements such as transistors as well as resistors which by nature create noise. Typically the components which are located at the input stage of an amp will contribute most to the overall noise. Consequently makers typically will pick low-noise components when developing the amplifier input stage.
Many of modern amplifiers are based on a digital switching architecture. They are referred to as "class-D" or "class-T" amps. Switching amplifiers include a power stage that is always switched at a frequency of approximately 400 kHz. This switching noise may result in a certain level of loudspeaker distortion yet is frequently not included in the the signal-to-noise ratio which merely considers noise between 20 Hz and 20 kHz.
The most common method for measuring the signal-to-noise ratio is to set the amplifier to a gain which allows the maximum output swing. Subsequently a test signal is input to the amp. The frequency of this signal is typically 1 kHz. The amplitude of this signal is 60 dB below the full scale signal. After that the noise-floor energy is measured in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.
Frequently the signal-to-noise ratio is shown in a more subjective method as "dbA" or "A weighted". This technique was designed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most sensitive to signals around 1 kHz. Then again, signals under 50 Hz and above 13 kHz are hardly heard. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is typically higher than the unweighted signal-to-noise ratio.
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You can find further information about power amplifier models as well as t-amps from Amphony's website.
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