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To help you decide on an audio amp, I will explain the expression "signal-to-noise ratio" which is regularly used to describe the performance of audio amps. Once you have chosen a range of amplifiers, it's time to investigate a few of the specs in more detail in order to help you narrow down your search to one product. One important parameter of power amplifiers is the signal-to-noise ratio. To put it simply, the signal-to-noise ratio describes how much hum or hiss the amplifier is going to add to the music signal. This ratio is usually shown in decibel or "db" for short.
You can make a simple comparison of the amplifier noise by short circuiting the amplifier input, setting the volume to maximum and listening to a speaker connected to the amplifier. The noise which you hear is produced by the amplifier itself. Next compare different amplifiers according to the next rule: the smaller the level of hiss, the higher the noise performance of the amp. Though, bear in mind that you have to set all amplifiers to amplify by the same level in order to compare several amps.
Comparing the noise level of several amplifiers may be done fairly easily. Simply gather a couple of versions which you want to evaluate and short circuit the inputs. Then put the amp volume to maximum and verify the level of noise by listening to the loudspeaker. You will hear some amount of hissing and/or hum coming from the loudspeaker. This noise is created by the amplifier itself. Make sure that the gain of the amplifiers is set to the same amount. Otherwise you will not be able to objectively evaluate the level of noise between several amplifiers. The general rule is: the smaller the amount of hiss which you hear the higher the noise performance. While glancing at the amp spec sheet, you want to look for an amplifier with a large signal-to-noise ratio number which indicates that the amp outputs a low amount of noise. There are several reasons why power amplifiers will add some form of hiss or other unwanted signal. Transistors and resistors which are part of every modern amp by nature make noise. The overall noise is dependent on how much noise each element creates. Nonetheless, the position of these components is also significant. Components that are part of the amplifier input stage will generally contribute the majority of the noise.
A lot of of modern amplifiers are based on a digital switching architecture. They are known as "class-D" or "class-T" amplifiers. Switching amplifiers incorporate a power stage that is always switched at a frequency of around 400 kHz. As a result, the output signal of switching amplifiers have a moderately big amount of switching noise. This noise component, though, is usually impossible to hear as it is well above 20 kHz. On the other hand, it may still contribute to speaker distortion. Signal-to-noise ratio is normally only shown within the range of 20 Hz to 20 kHz. For that reason, a lowpass filter is utilized when measuring switching amplifiers to remove the switching noise.
The most common technique for measuring the signal-to-noise ratio is to set the amplifier to a gain that allows the maximum output swing. After that a test tone is fed to the amplifier. The frequency of this signal is usually 1 kHz. The amplitude of this tone is 60 dB underneath the full scale signal. After that, the noise floor between 20 Hz and 20 kHz is measured and the ratio to the full-scale signal computed. The noise signal at different frequencies is eliminated via a bandpass filter during this measurement.
Frequently you are going to discover the expression "dBA" or "a-weighted" in your amp parameter sheet. A weighting is a technique of showing the noise floor in a more subjective manner. This technique tries to examine in how far the amplifier noise is perceived by human hearing which is most responsive to signals at frequencies at 1 kHz. Consequently an A-weighting filter is going to magnify the noise floor for frequencies which are easily perceived and suppress the noise floor at frequencies which are hardly noticed. The majority of amplifiers will show a higher A-weighted signal-to-noise ratio than the un-weighted ratio.
You can make a simple comparison of the amplifier noise by short circuiting the amplifier input, setting the volume to maximum and listening to a speaker connected to the amplifier. The noise which you hear is produced by the amplifier itself. Next compare different amplifiers according to the next rule: the smaller the level of hiss, the higher the noise performance of the amp. Though, bear in mind that you have to set all amplifiers to amplify by the same level in order to compare several amps.
Comparing the noise level of several amplifiers may be done fairly easily. Simply gather a couple of versions which you want to evaluate and short circuit the inputs. Then put the amp volume to maximum and verify the level of noise by listening to the loudspeaker. You will hear some amount of hissing and/or hum coming from the loudspeaker. This noise is created by the amplifier itself. Make sure that the gain of the amplifiers is set to the same amount. Otherwise you will not be able to objectively evaluate the level of noise between several amplifiers. The general rule is: the smaller the amount of hiss which you hear the higher the noise performance. While glancing at the amp spec sheet, you want to look for an amplifier with a large signal-to-noise ratio number which indicates that the amp outputs a low amount of noise. There are several reasons why power amplifiers will add some form of hiss or other unwanted signal. Transistors and resistors which are part of every modern amp by nature make noise. The overall noise is dependent on how much noise each element creates. Nonetheless, the position of these components is also significant. Components that are part of the amplifier input stage will generally contribute the majority of the noise.
A lot of of modern amplifiers are based on a digital switching architecture. They are known as "class-D" or "class-T" amplifiers. Switching amplifiers incorporate a power stage that is always switched at a frequency of around 400 kHz. As a result, the output signal of switching amplifiers have a moderately big amount of switching noise. This noise component, though, is usually impossible to hear as it is well above 20 kHz. On the other hand, it may still contribute to speaker distortion. Signal-to-noise ratio is normally only shown within the range of 20 Hz to 20 kHz. For that reason, a lowpass filter is utilized when measuring switching amplifiers to remove the switching noise.
The most common technique for measuring the signal-to-noise ratio is to set the amplifier to a gain that allows the maximum output swing. After that a test tone is fed to the amplifier. The frequency of this signal is usually 1 kHz. The amplitude of this tone is 60 dB underneath the full scale signal. After that, the noise floor between 20 Hz and 20 kHz is measured and the ratio to the full-scale signal computed. The noise signal at different frequencies is eliminated via a bandpass filter during this measurement.
Frequently you are going to discover the expression "dBA" or "a-weighted" in your amp parameter sheet. A weighting is a technique of showing the noise floor in a more subjective manner. This technique tries to examine in how far the amplifier noise is perceived by human hearing which is most responsive to signals at frequencies at 1 kHz. Consequently an A-weighting filter is going to magnify the noise floor for frequencies which are easily perceived and suppress the noise floor at frequencies which are hardly noticed. The majority of amplifiers will show a higher A-weighted signal-to-noise ratio than the un-weighted ratio.
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