It is easy to be bewildered by the terminology that amplifier producers employ to depict the performance of their models. I am going to clarify the meaning of one regularly utilized amp spec: "signal-to-noise ratio" to help you make an informed decision whilst purchasing a new amp.
You can make a simple assessment of the amp hiss by short circuiting the amp input, setting the gain to maximum and listening to a speaker attached to the amplifier. You will hear some amount of hissing and/or hum coming from the speaker. This hiss is created by the amp itself. Be certain that the gain of the amps is set to the same amount. Otherwise you will not be able to objectively compare the level of static between different amps. The general rule is: the smaller the level of static which you hear the higher the noise performance.
One way in order to accomplish a simple test of the noise performance of an amplifier is to short circuit the amplifier input and then to crank up the amp to its utmost. Then listen to the loudspeaker that you have connected. The noise that you hear is produced by the amplifier itself. Make certain that the volume of the amps is set to the same amount. Otherwise you will not be able to objectively evaluate the amount of hiss between different amps. The general rule is: the smaller the amount of noise that you hear the higher the noise performance. In order to help you compare the noise performance, amplifier makers show the signal-to-noise ratio in their amplifier spec sheets. Simply put, the larger the signal-to-noise ratio, the smaller the level of noise the amp produces. Noise is produced due to a number of reasons. One reason is that today's amps all use components like transistors plus resistors. These elements will produce some amount of noise. Typically the components that are located at the input stage of an amp will contribute most to the overall hiss. Consequently suppliers generally will select low-noise components when designing the amp input stage.
A lot of of today's amplifiers are based on a digital switching architecture. They are named "class-D" or "class-T" amps. Switching amplifiers include a power stage which is constantly switched at a frequency of approximately 400 kHz. This switching noise may cause a certain amount of loudspeaker distortion but is frequently not included in the the signal-to-noise ratio which only considers noise between 20 Hz and 20 kHz.
A lot of today's power amps incorporate a wattage switching stage which switches at a frequency around 500 kHz. As a result, the output signal of switching amps contain a rather big level of switching noise. This noise component, though, is generally impossible to hear since it is well above 20 kHz. Though, it can still contribute to loudspeaker distortion. Signal-to-noise ratio is typically only shown within the range of 20 Hz to 20 kHz. As a result, a lowpass filter is used while measuring switching amps to eliminate the switching noise. The most widespread technique for measuring the signal-to-noise ratio is to set the amp to a gain which permits the maximum output swing. After that a test tone is fed to the amp. The frequency of this signal is generally 1 kHz. The amplitude of this tone is 60 dB below the full scale signal. Then, only the noise between 20 Hz and 20 kHz is considered. The noise at other frequencies is eliminated through a filter. Then the amount of the noise energy in relation to the full-scale output wattage is calculated and shown in decibel.
Time and again you are going to find the expression "dBA" or "a-weighted" in your amplifier specification sheet. A weighting is a technique of showing the noise floor in a more subjective fashion. This method was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most perceptive to signals around 1 kHz. However, signals under 50 Hz and higher than 13 kHz are hardly noticed. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is normally larger than the unweighted signal-to-noise ratio.
You can make a simple assessment of the amp hiss by short circuiting the amp input, setting the gain to maximum and listening to a speaker attached to the amplifier. You will hear some amount of hissing and/or hum coming from the speaker. This hiss is created by the amp itself. Be certain that the gain of the amps is set to the same amount. Otherwise you will not be able to objectively compare the level of static between different amps. The general rule is: the smaller the level of static which you hear the higher the noise performance.
One way in order to accomplish a simple test of the noise performance of an amplifier is to short circuit the amplifier input and then to crank up the amp to its utmost. Then listen to the loudspeaker that you have connected. The noise that you hear is produced by the amplifier itself. Make certain that the volume of the amps is set to the same amount. Otherwise you will not be able to objectively evaluate the amount of hiss between different amps. The general rule is: the smaller the amount of noise that you hear the higher the noise performance. In order to help you compare the noise performance, amplifier makers show the signal-to-noise ratio in their amplifier spec sheets. Simply put, the larger the signal-to-noise ratio, the smaller the level of noise the amp produces. Noise is produced due to a number of reasons. One reason is that today's amps all use components like transistors plus resistors. These elements will produce some amount of noise. Typically the components that are located at the input stage of an amp will contribute most to the overall hiss. Consequently suppliers generally will select low-noise components when designing the amp input stage.
A lot of of today's amplifiers are based on a digital switching architecture. They are named "class-D" or "class-T" amps. Switching amplifiers include a power stage which is constantly switched at a frequency of approximately 400 kHz. This switching noise may cause a certain amount of loudspeaker distortion but is frequently not included in the the signal-to-noise ratio which only considers noise between 20 Hz and 20 kHz.
A lot of today's power amps incorporate a wattage switching stage which switches at a frequency around 500 kHz. As a result, the output signal of switching amps contain a rather big level of switching noise. This noise component, though, is generally impossible to hear since it is well above 20 kHz. Though, it can still contribute to loudspeaker distortion. Signal-to-noise ratio is typically only shown within the range of 20 Hz to 20 kHz. As a result, a lowpass filter is used while measuring switching amps to eliminate the switching noise. The most widespread technique for measuring the signal-to-noise ratio is to set the amp to a gain which permits the maximum output swing. After that a test tone is fed to the amp. The frequency of this signal is generally 1 kHz. The amplitude of this tone is 60 dB below the full scale signal. Then, only the noise between 20 Hz and 20 kHz is considered. The noise at other frequencies is eliminated through a filter. Then the amount of the noise energy in relation to the full-scale output wattage is calculated and shown in decibel.
Time and again you are going to find the expression "dBA" or "a-weighted" in your amplifier specification sheet. A weighting is a technique of showing the noise floor in a more subjective fashion. This method was developed with the knowledge that human hearing perceives noise at different frequencies differently. Human hearing is most perceptive to signals around 1 kHz. However, signals under 50 Hz and higher than 13 kHz are hardly noticed. An A-weighted signal-to-noise ratio weighs the noise floor according to the human hearing and is normally larger than the unweighted signal-to-noise ratio.
About the Author:
Read the article about digital amplifiers. Additionally, stop by http://amplifiershifi.com/.
Aucun commentaire:
Enregistrer un commentaire