Analogous means similar, that is, the electrical current that passes through a circuit, such as an audio amplifier or mixing console, varies similarly to the variations in air pressure that sound represents.
In the case of a vinyl record, the groove shape is similar to the sound waveform.
When the sound presses the membrane of a microphone it produces an alternating electric current (which permanently changes polarity or direction of movement through the conductor or cable). If we plot the sound pressure variations as a function of time it will give a curve similar to the one we get if we plot the alternating current variations. In turn, the speaker that reproduces the sound will move forward or backward following that graph.
In an analog audio system there are no calculations or more processes than simply converting a mechanical energy (sound waves) to electrical energy and vice versa.
In an analog mixing console, the sound undergoes simple processes by crossing circuits that attenuate or amplify it, at most according to each frequency (equalizers or filters), delay it, add it to other sounds, etc.
The old analog synthesizers were called in this way because the resulting sound followed the voltage variations of electronic oscillators or combinations thereof.
Digital sound
Digital systems convert the audio signal into data that can be processed by numerical calculations.
The numbers that are handled are not given in the commonly used decimal system but in the binary system in which a number can be represented as a succession of ones and zeros; a one means “there is voltage” (for example, more than 3 volts), while a zero means “there is no voltage” (or is less than, for example, 3 volts).
When an analog audio signal enters a digital device, the level or amplitude is measured at small intervals of time by assigning a binary number to each one.
This is called the Analog / Digital Converter (A / D).
If you want to recover the sound wave a circuit called Digital / Analog Converter will put in its output a voltage (voltage) that will correspond to the binary numbers that had been measured. This output signal is filtered to smooth out sudden changes in levels and get closer to the original waveform.
When we have the sound represented with binary numbers we can with these do calculation processes as do the DSP (Digital Signal Processor) effect processors to give the sound reverberance, echo, chorus, etc.
The advantage of working with digital equipment is that the noise does not affect the information because its level (voltage) is much lower than that of a binary digit. On the contrary, in an analog system the noise has a level very close to the softer sounds that are handled, for example, in a mixing console in which noises from different sound sources and circuits are added.
Resolution
It is the amount of bits (binary digits) that are used to obtain each binary number that corresponds to each point of the curve.
With 8 bits we can represent values or levels from 0 to 255. With this you get a very precise and noisy digital wave, not at all true to the original sound.
With 24 bits, the most commonly used resolution in professional sound, we can represent the wave with values between 0 and 16,777,215, which gives an extremely accurate sound wave. The 32-bit resolution is also commonly used.
Sample Rate
It is another parameter that determines the quality of digital audio and measures the number of samples (level measurement) that are taken per second. The higher the sampling rate, the higher the audio quality because less time elapses between one measurement and another allowing us greater accuracy.
It is measured in Kbits / sec (kilobits per second – kilo = 1000)
In CD quality 128 kbit / s are taken
