A Few Guidelines To Help Comprehend The Noise Performance Of Recent Audio AmpsTo help you select an audio amp, I will explain the expression "signal-to-noise ratio" which is commonly utilized to describe the performance of audio amps. As soon as you have selected a range of amplifiers, it's time to investigate a few of the specs in more detail in order to help you narrow down your search to one model. Every amp is going to produce a certain amount of hiss and hum. Then listen to the speaker that you have attached. However, keep in mind that you have to set all amplifiers to amplify by the same amount to compare different amps.
If you prefer an amplifier with a small amount of hissing, you may look at the signal-to-noise ratio figure of the data sheet. A lot of makers are going to show this figure. Amps with a high signal-to-noise ratio will output a small amount of static. Transistors and resistors which are part of each modern amp by nature make noise. Therefore makers usually will pick low-noise components whilst designing the amplifier input stage.
The majority of modern power amps are digital small audio amps, also known as "class-d amplifiers". Class-D amplifiers utilize a switching stage which oscillates at a frequency between 300 kHz to 1 MHz. On the other hand, modern amplifier specifications typically only consider the hiss between 20 Hz and 20 kHz. Manufacturers measure the signal-to-noise ratio by means of setting the amplifier such that the full output swing can be realized and by feeding a test signal to the amp which is normally 60 dB below the full scale of the amplifier. Subsequently the noise-floor energy is measured in the frequency range between 20 Hz and 20 kHz and compared with the full scale signal energy. You are going to spot these terms in a lot of amp specification sheets. 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. Thus an A-weighting filter is going to amplify the noise floor for frequencies that are easily heard and suppress the noise floor at frequencies that are barely noticed.