When selecting a brand new amplifier, you probably
An amplifier is designed to amplify an audio signal enough to drive a couple of speakers to medium or high sound level. Suppliers usually present the frequency range over which the amp works. This range is specified by listing 2 frequencies: a lower and upper frequency. For example, the lower frequency may be 20 Hz and the upper frequency 20 kHz. Using this spec it seems the amp could work as a HIFI amplifier. You may be lured to select an amplifier that offers the biggest frequency response. Yet, there is far more to knowing an amplifier's overall performance than simply understanding this simple range.
The fact is, an amplifier which has a frequency response from 10 Hz to 30 kHz can in fact have much worse sound quality than an amplifier which provides a frequency response from 20 Hz to 15 kHz. Different producers often make use of different methods to determine frequency response. The conventional convention is to display the frequency range inside of which the amplification is going to decrease at most 3 dB from the nominal gain.
However, some manufacturers push this standard to the limit and may show a maximum frequency where the amplifier is going to barely generate a signal anymore. In addition, just reviewing these 2 figures doesn't say a lot about the linearity of the frequency response. If possible you should make an effort to obtain a frequency response diagram from the maker. In this diagram, you'll find how the amplifier behaves inside the frequency response range. You can also spot any peaks or valleys the amp could have. Also you can wish to demand a phase response diagram which offers crucial clues in regards to the sound quality.
You additionally want to look at the conditions under which the frequency response was calculated. You typically are not going to find any kind of details about the measurement conditions, unfortunately, in the producer's data sheet. Actually amplifiers may have different frequency responses depending on the speaker which is attached.
Mostly current digital or 'Class-D' amps will show changes in the frequency response with various loads. The main reason is the fact that Class-D amps utilize switching FETs as the power phase which produce a great deal of switching components. These components are eliminated with a filter which is part of the amp. A changing speaker load is going to affect the filter response to some amount. Generally the lower the loudspeaker impedance the lower the highest frequency of the amp. Furthermore, the linearity of the amplifier gain will be determined by the load.
Various amplifier topologies offer a method to compensate for variations in the amplifier gain with various loudspeaker loads. One of these techniques makes use of feedback. The amplifier output signal after the interior lowpass is input to the amplifier input for comparison. If not created correctly, this technique might cause instability of the amp however. Different amps make use of transformers and offer outputs for several loudspeaker loads. Apart from improving the frequency response of the amplifier, this technique normally furthermore improves the amplifier efficiency.