Archive 'Amplifier'

In the light of what we have seen up until now, we are now ready to analyze the sampling process in all its various phases.

There are audio signal generators that have very high internal impedance values, and are therefore difficult to manage by the means we have mentioned up until now and with common amplifiers. A high internal impedance in fact means loss of voltage on the transferred signal; very rarely will an amplifying stage have an input impedance which equals at least 10 times the one inside the signal generator.

In our case, let's take an amplifier's output which supplies a signal with voltage V and power P. As mentioned, amplifiers have an output impedance Zu. In this case what we're interested in is to guarantee maximum power transfer from the amplifier to the loudspeaker.

As with other components in the audio world, an amplifier also is given a frequency response through which we can evaluate its quality. What we want from an amplifier is that it returns the signal band that we send at the input without any alterations, in other words, we want a flat response on the entire frequency band we're interested in.

It describes the amplifier's action on the input signal. The following diagram illustrates a voltage amplifier's possible amplification curve.

For a complete study of amplifying circuits we advise the reader to refer to specialized textbooks on the subject. Here we will be looking at the main aspects of the functions and characteristics that relate to the correct calibration of an audio amplifying system.

An electric signal that is generated by an acoustic source, such as a signal issuing from a microphone, must be correctly amplified before it reaches the diffusers.

What we've said up to now with regards to sinusoids is a fundamental truth upon which we will base the rest of our sound reality. An aspect which contributes a lot to the characteristics of sound is its harmonics.