When purchasing a new amp, you almost certainly are going to take a look at the technical features. An often found specification is the frequency response. This specification while significant doesn't tell the entire story with regards to how good the amp is going to sound. I am going to make clear the meaning of this phrase and even offer a few recommendations on how to interpret it whilst looking for an amp.
It seems there are various approaches that manufacturers utilize whilst specifying the frequency response. Usually, the frequency response shows the normal operating range of the amplifier. Inside this range, the amp gain is largely constant. At the upper and lower cutoff frequencies the gain is going to decrease by at most 3 decibels.
On the other hand, several makers push this standard to the limit and tend to show a maximum frequency where the amplifier is going to barely produce a signal anymore. In addition, simply reviewing these 2 numbers does not say a lot concerning the linearity of the frequency response. A complete frequency response graph, however, will show if there are any kind of peaks or valleys and in addition show the way the frequency response is to be understood. Peaks and valleys can result in colorization of the music. Ideally the amplifier should have a constant amplification within the complete frequency response except for the drop off at the upper and lower limit. Apart from the frequency response, a phase response diagram may also say a great deal regarding the overall performance and sound quality of the amplifier.
To better understand the frequency response behavior of a certain model, you should make an effort to find out under which conditions the response was measured. You will probably find these details in the data sheet of the amp. Then again, many makers are not going to show those in which case you should make contact with the manufacturer directly. One condition which can effect the frequency response is the impedance of the loudspeaker connected to the amplifier. Standard speaker impedances range between 2 to 16 Ohms. The lower the speaker impedance the greater the load for the amplifier. The frequency response of Class-D amps shows the biggest change with different speaker loads due to the integrated lowpass filter that removes switching noise from the amplifier's signal. However, the frequency response of the amplifier now varies according to the loudspeaker load considering that the behavior of this lowpass filter is affected by the load impedance. Usually the lower the speaker load impedance the lower the upper cut-off frequency of the amplifier
This change is most detectable with a lot of digital amps, otherwise known as Class-D amps. Class-D amplifiers have a lowpass filter inside their output as a way to reduce the switching components that are produced through the internal power FETs. A varying loudspeaker load is going to impact the filter response to some degree. Commonly the lower the speaker impedance the lower the maximum frequency of the amp. Moreover, the linearity of the amplifier gain will be determined by the load. Various amplifier topologies offer a mechanism to compensate for changes in the amplifier gain with various loudspeaker loads. One of these methods employs feedback. The amplifier output signal after the interior lowpass is input to the amplifier input for comparison. If not designed adequately, this approach could cause instability of the amp though. A different technique is to offer dedicated outputs for different loudspeaker impedances that are attached to the amp power phase by way of audio transformers.
It seems there are various approaches that manufacturers utilize whilst specifying the frequency response. Usually, the frequency response shows the normal operating range of the amplifier. Inside this range, the amp gain is largely constant. At the upper and lower cutoff frequencies the gain is going to decrease by at most 3 decibels.
On the other hand, several makers push this standard to the limit and tend to show a maximum frequency where the amplifier is going to barely produce a signal anymore. In addition, simply reviewing these 2 numbers does not say a lot concerning the linearity of the frequency response. A complete frequency response graph, however, will show if there are any kind of peaks or valleys and in addition show the way the frequency response is to be understood. Peaks and valleys can result in colorization of the music. Ideally the amplifier should have a constant amplification within the complete frequency response except for the drop off at the upper and lower limit. Apart from the frequency response, a phase response diagram may also say a great deal regarding the overall performance and sound quality of the amplifier.
To better understand the frequency response behavior of a certain model, you should make an effort to find out under which conditions the response was measured. You will probably find these details in the data sheet of the amp. Then again, many makers are not going to show those in which case you should make contact with the manufacturer directly. One condition which can effect the frequency response is the impedance of the loudspeaker connected to the amplifier. Standard speaker impedances range between 2 to 16 Ohms. The lower the speaker impedance the greater the load for the amplifier. The frequency response of Class-D amps shows the biggest change with different speaker loads due to the integrated lowpass filter that removes switching noise from the amplifier's signal. However, the frequency response of the amplifier now varies according to the loudspeaker load considering that the behavior of this lowpass filter is affected by the load impedance. Usually the lower the speaker load impedance the lower the upper cut-off frequency of the amplifier
This change is most detectable with a lot of digital amps, otherwise known as Class-D amps. Class-D amplifiers have a lowpass filter inside their output as a way to reduce the switching components that are produced through the internal power FETs. A varying loudspeaker load is going to impact the filter response to some degree. Commonly the lower the speaker impedance the lower the maximum frequency of the amp. Moreover, the linearity of the amplifier gain will be determined by the load. Various amplifier topologies offer a mechanism to compensate for changes in the amplifier gain with various loudspeaker loads. One of these methods employs feedback. The amplifier output signal after the interior lowpass is input to the amplifier input for comparison. If not designed adequately, this approach could cause instability of the amp though. A different technique is to offer dedicated outputs for different loudspeaker impedances that are attached to the amp power phase by way of audio transformers.
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