What is the difference between Digital volume control and Analog volume control?

[GUOJIMIAO]

Hi, All!
Newbie here. I've been trying for a few days now to understand the difference between Digital volume control and Analog volume control but to no avail. I've tried to read about it on Youtube and find an example of CS3308, even this article with some details about Analog volume control:https://www.utmel.com/components/cs3308-analog-volume-control-pinout-features-and-datasheet?id=324 but they don't really explain the difference in them. Too many long words Could somebody here please explain the difference? All help will be much appreciated. Thanks in advance

 

[danadakk]

Analog control means you supply an analog V or I to a circuit or module which alters its
gain to a signal.

Digital control means you supply a digital byte or word to a controller which uses that
value to set gain. Internally how it does that can take many forms, one common tech-
nique using a D/A internally to change the digital byte/word into a V or I that alters circuit G.
Another technique is digital byte/word sent to multiplying DAC to alter the signal path G.

New High-Resolution Multiplying DACs Excel at Handling AC Signals | Analog Devices

A look at resistance-ladder multiplying DACs and their inherent suitability for ac signal-processing applications.

www.analog.com

Regards, Dana.

 

[betwixt]

I'll try to explain in small words

There are several ways to vary volume. The simplest is a potentiometer that passes on a proportion of the audio depending on the position of the control. It is an adjustable voltage divider, as you turn the control or move the slider, the ratio of resistances between its pins changes and that changes how much is allowed to pass through.

There are also shunt volume controls that are less commonly used where a fixed resistance is placed in series with the audio and it is followed by a device (usually a FET or LDR) that is voltage controlled but produces a variable resistance to ground. It works the same way as a potentiometer but only the lower part of the total resistance is changed.

Digital control can do the same thing but in two different ways. The easiest to visualize is a DAC (Digital to Analog Converter), it uses a line of fixed resistors with the full volume applied at the top and ground at the bottom. A proportion of the full volume is available at the junction of each resistor. The digital part is a circuit that uses the number you pass to it to open an analog switch. That switch couples the selected resistors junction to the output pin. Changing the digital input opens a switch nearer the top of the chain for more volume or lower in the chain for less volume.

The other digital method is similar but instead of dividing the full signal to give a lower level, the switched resistors are in the negative feedback path of an amplifier. The selected resistance sets the gain of the amplifier and hence the output level.

Brian.