It is easy to be puzzled by the terminology which amp makers use in order to explain the performance of their products. I am going to clarify the meaning of one frequently used amplifier specification: "signal-to-noise ratio" to help you make an informed choice while getting a new amplifier.
You can do a simple comparison of the amp noise by short circuiting the amplifier 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 noise is produced by the amp itself. Make sure that the volume of the amplifiers is set to the same level. Otherwise you will not be able to objectively compare the level of noise between several amplifiers. The general rule is: the smaller the amount of static which you hear the better the noise performance.
You can do a straightforward 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. The noise which you hear is created by the amplifier itself. Be certain that the volume of the amplifiers is set to the same amount. Otherwise you will not be able to objectively compare the level of hiss between different amplifiers. The general rule is: the smaller the amount of static which you hear the higher the noise performance.
When looking at the amplifier specification sheet, you want to look for an amplifier with a large signal-to-noise ratio figure which suggests that the amplifier outputs a low level of noise. One of the reasons why amps produce noise is the fact that they utilize elements such as transistors as well as resistors which by nature create noise. Because the amp overall noise performance is mostly determined by the performance of components situated at the amp input, producers will try to select low-noise parts while designing the amplifier input stage.
The majority of modern power amps are digital amplifiers, also known as "class-d amplifiers". Class-D amplifiers employ a switching stage which oscillates at a frequency in the range of 300 kHz to 1 MHz. This switching noise can result in a certain amount of speaker distortion yet is typically 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 enables the maximum output swing. Next a test tone is fed to the amplifier. The frequency of this tone is generally 1 kHz. The amplitude of this tone is 60 dB below the full scale signal. Next, the noise floor between 20 Hz and 20 kHz is measured and the ratio to the full-scale signal calculated. The noise signal at different frequencies is removed by a bandpass filter during this measurement.
Time and again 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. In other words, this technique tries to express how the noise is perceived by a human being. Human hearing is most perceptive to signals around 1 kHz while signals under 50 Hz and above 14 kHz are barely noticed. The A-weighted signal-to-noise ratio is generally higher than the unweighted ratio and is shown in the majority of amplifier specification sheets.
You can do a simple comparison of the amp noise by short circuiting the amplifier 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 noise is produced by the amp itself. Make sure that the volume of the amplifiers is set to the same level. Otherwise you will not be able to objectively compare the level of noise between several amplifiers. The general rule is: the smaller the amount of static which you hear the better the noise performance.
You can do a straightforward 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. The noise which you hear is created by the amplifier itself. Be certain that the volume of the amplifiers is set to the same amount. Otherwise you will not be able to objectively compare the level of hiss between different amplifiers. The general rule is: the smaller the amount of static which you hear the higher the noise performance.
When looking at the amplifier specification sheet, you want to look for an amplifier with a large signal-to-noise ratio figure which suggests that the amplifier outputs a low level of noise. One of the reasons why amps produce noise is the fact that they utilize elements such as transistors as well as resistors which by nature create noise. Because the amp overall noise performance is mostly determined by the performance of components situated at the amp input, producers will try to select low-noise parts while designing the amplifier input stage.
The majority of modern power amps are digital amplifiers, also known as "class-d amplifiers". Class-D amplifiers employ a switching stage which oscillates at a frequency in the range of 300 kHz to 1 MHz. This switching noise can result in a certain amount of speaker distortion yet is typically 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 enables the maximum output swing. Next a test tone is fed to the amplifier. The frequency of this tone is generally 1 kHz. The amplitude of this tone is 60 dB below the full scale signal. Next, the noise floor between 20 Hz and 20 kHz is measured and the ratio to the full-scale signal calculated. The noise signal at different frequencies is removed by a bandpass filter during this measurement.
Time and again 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. In other words, this technique tries to express how the noise is perceived by a human being. Human hearing is most perceptive to signals around 1 kHz while signals under 50 Hz and above 14 kHz are barely noticed. The A-weighted signal-to-noise ratio is generally higher than the unweighted ratio and is shown in the majority of amplifier specification sheets.
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