It is easy to be bewildered by the terminology that amplifier manufacturers use in order to describe the performance of their models. I am going to explain the meaning of one usually used amp spec: "signal-to-noise ratio" in order to help you make an informed decision whilst purchasing a new amplifier.
Comparing the noise level of several amplifiers may be accomplished rather easily. Just gather a couple of models which you wish to evaluate and short circuit the inputs. Afterward put the amplifier gain to maximum and verify the amount of static by listening to the loudspeaker. The noise that you hear is created by the amp itself. Make certain 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 different amps. The general rule is: the lower the amount of hiss which you hear the better the noise performance.
If you prefer an amp with a small level of hissing, you may look at the signal-to-noise ratio number of the data sheet. Most producers are going to display this number. Amplifiers with a high signal-to-noise ratio will output a small level of noise. There are a number of reasons why power amps will add some form of noise or other unwanted signal. Transistors and resistors which are part of every modern amp by nature produce noise. Generally the components that are situated at the input stage of an amp will contribute most to the overall noise. Thus suppliers generally are going to pick low-noise components when designing the amp input stage.
The majority of today's power amps are digital amps, also referred to as "class-d amps". Class-D amplifiers make use of a switching stage that oscillates at a frequency between 300 kHz to 1 MHz. As a result, the output signal of switching amplifiers exhibit a moderately big level of switching noise. This noise component, however, is usually inaudible since it is well above 20 kHz. However, it can still contribute to loudspeaker distortion. Signal-to-noise ratio is usually only shown within the range of 20 Hz to 20 kHz. As a result, a lowpass filter is utilized when measuring switching amps to eliminate the switching noise.
The signal-to-noise ratio is measured by feeding a 1 kHz test signal 60 dB underneath the full scale and measuring the noise floor of the amplifier. The amplification of the amplifier is set such that the full output wattage of the amplifier can be realized. Next the noise-floor energy is calculated in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.
Time and again you are going to discover the expression "dBA" or "a-weighted" in your amplifier specification sheet. A weighting is a technique of expressing the noise floor in a more subjective manner. This technique tries to evaluate in how far the amp noise is perceived by human hearing which is most responsive to signals at frequencies at 1 kHz. The A-weighted signal-to-noise ratio is usually higher than the unweighted ratio and is shown in a lot of amp specification sheets.
Comparing the noise level of several amplifiers may be accomplished rather easily. Just gather a couple of models which you wish to evaluate and short circuit the inputs. Afterward put the amplifier gain to maximum and verify the amount of static by listening to the loudspeaker. The noise that you hear is created by the amp itself. Make certain 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 different amps. The general rule is: the lower the amount of hiss which you hear the better the noise performance.
If you prefer an amp with a small level of hissing, you may look at the signal-to-noise ratio number of the data sheet. Most producers are going to display this number. Amplifiers with a high signal-to-noise ratio will output a small level of noise. There are a number of reasons why power amps will add some form of noise or other unwanted signal. Transistors and resistors which are part of every modern amp by nature produce noise. Generally the components that are situated at the input stage of an amp will contribute most to the overall noise. Thus suppliers generally are going to pick low-noise components when designing the amp input stage.
The majority of today's power amps are digital amps, also referred to as "class-d amps". Class-D amplifiers make use of a switching stage that oscillates at a frequency between 300 kHz to 1 MHz. As a result, the output signal of switching amplifiers exhibit a moderately big level of switching noise. This noise component, however, is usually inaudible since it is well above 20 kHz. However, it can still contribute to loudspeaker distortion. Signal-to-noise ratio is usually only shown within the range of 20 Hz to 20 kHz. As a result, a lowpass filter is utilized when measuring switching amps to eliminate the switching noise.
The signal-to-noise ratio is measured by feeding a 1 kHz test signal 60 dB underneath the full scale and measuring the noise floor of the amplifier. The amplification of the amplifier is set such that the full output wattage of the amplifier can be realized. Next the noise-floor energy is calculated in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy.
Time and again you are going to discover the expression "dBA" or "a-weighted" in your amplifier specification sheet. A weighting is a technique of expressing the noise floor in a more subjective manner. This technique tries to evaluate in how far the amp noise is perceived by human hearing which is most responsive to signals at frequencies at 1 kHz. The A-weighted signal-to-noise ratio is usually higher than the unweighted ratio and is shown in a lot of amp specification sheets.
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