It is easy to be puzzled by the terminology that amp makers employ in order to describe the performance of their products. I will explain the meaning of one regularly used amplifier specification: "signal-to-noise ratio" in order to help you make an informed decision when getting a brand new amp.
Whilst looking for an amplifier, you initially are going to check the cost, power amid other fundamental criteria. However, after this initial selection, you are going to still have a number of models to choose from. Now you will focus more on some of the technical specs, such as signal-to-noise ratio as well as harmonic distortion. Every amp will create a certain level of hiss as well as hum. The signal-to-noise ratio will help quantify the level of hiss created by the amp.
Evaluating the noise level of different amps can be accomplished rather simply. Simply get together a couple of versions which you want to evaluate and short circuit the inputs. Then put the amplifier gain to maximum and verify the level of hiss by listening to the speaker. The hiss that you hear is created by the amp itself. Make sure that the volume of the amps is set to the same amount. Otherwise you will not be able to objectively compare the amount of noise between several amps. The general rule is: the smaller the level of static which you hear the higher the noise performance. Whilst taking a look at the amp specification sheet, you want to look for an amp with a large signal-to-noise ratio number which indicates that the amplifier outputs a low level of static. One of the reasons why amplifiers generate noise is the fact that they use elements including transistors and resistors that by nature create noise. The overall noise is dependent on how much hiss each element creates. Nonetheless, the location of those elements is also significant. Elements that are part of the amplifier input stage will in general contribute the majority of the noise.
Most of latest amps are based on a digital switching architecture. They are referred to as "class-D" or "class-T" amplifiers. Switching amplifiers incorporate a power stage which is continuously switched at a frequency of approximately 400 kHz. As a result, the output signal of switching amplifiers have a rather large level of switching noise. This noise component, though, is generally impossible to hear because it is well above 20 kHz. Though, 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 used while measuring switching amps in order to eliminate the switching noise.
Makers measure the signal-to-noise ratio by means of setting the amplifier such that the full output swing may be achieved and by feeding a test signal to the amplifier that is generally 60 dB below the full scale of the amp. After that, the noise floor between 20 Hz and 20 kHz is calculated and the ratio to the full-scale signal calculated. The noise signal at other frequencies is removed via a bandpass filter throughout this measurement.
Frequently you will discover the term "dBA" or "a-weighted" in your amp spec sheet. A weighting is a technique of expressing the noise floor in a more subjective manner. In other words, this technique attempts 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 hardly noticed. The A-weighted signal-to-noise ratio is frequently larger than the unweighted ratio and is published in a lot of amplifier spec sheets.
Whilst looking for an amplifier, you initially are going to check the cost, power amid other fundamental criteria. However, after this initial selection, you are going to still have a number of models to choose from. Now you will focus more on some of the technical specs, such as signal-to-noise ratio as well as harmonic distortion. Every amp will create a certain level of hiss as well as hum. The signal-to-noise ratio will help quantify the level of hiss created by the amp.
Evaluating the noise level of different amps can be accomplished rather simply. Simply get together a couple of versions which you want to evaluate and short circuit the inputs. Then put the amplifier gain to maximum and verify the level of hiss by listening to the speaker. The hiss that you hear is created by the amp itself. Make sure that the volume of the amps is set to the same amount. Otherwise you will not be able to objectively compare the amount of noise between several amps. The general rule is: the smaller the level of static which you hear the higher the noise performance. Whilst taking a look at the amp specification sheet, you want to look for an amp with a large signal-to-noise ratio number which indicates that the amplifier outputs a low level of static. One of the reasons why amplifiers generate noise is the fact that they use elements including transistors and resistors that by nature create noise. The overall noise is dependent on how much hiss each element creates. Nonetheless, the location of those elements is also significant. Elements that are part of the amplifier input stage will in general contribute the majority of the noise.
Most of latest amps are based on a digital switching architecture. They are referred to as "class-D" or "class-T" amplifiers. Switching amplifiers incorporate a power stage which is continuously switched at a frequency of approximately 400 kHz. As a result, the output signal of switching amplifiers have a rather large level of switching noise. This noise component, though, is generally impossible to hear because it is well above 20 kHz. Though, 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 used while measuring switching amps in order to eliminate the switching noise.
Makers measure the signal-to-noise ratio by means of setting the amplifier such that the full output swing may be achieved and by feeding a test signal to the amplifier that is generally 60 dB below the full scale of the amp. After that, the noise floor between 20 Hz and 20 kHz is calculated and the ratio to the full-scale signal calculated. The noise signal at other frequencies is removed via a bandpass filter throughout this measurement.
Frequently you will discover the term "dBA" or "a-weighted" in your amp spec sheet. A weighting is a technique of expressing the noise floor in a more subjective manner. In other words, this technique attempts 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 hardly noticed. The A-weighted signal-to-noise ratio is frequently larger than the unweighted ratio and is published in a lot of amplifier spec sheets.
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