Audio transmission: digital vs analog
Today we will talk about a topic that is familiar to many folks, but not everyone understands the difference. If you look at any modern technology, such as your home receiver, you will see that it has an analog and digital input. Everyone seems to agree that “digital is better”, but why do manufacturers still offer analog audio transmission inputs?
Before the era of digitalization, there was only an analog signal to be talked about. Signals with different amplitudes were transmitted in one direction or another, and at the output the coil in the speakers produced vibrations that a human ear could catch. Generally speaking, the mechanism of delivering sound to people in the audience has not changed -- it still comes from the speakers that contain the coils. So why do we need a digital signal if we still get an analog output?
As our tech experts at Big Screen Pro often like to point out: the quality of an AV system is a function of its worst component. We have already touched and will continue to expand on the topic of speaker cables, their quality and how to pick the right speaker wires, but now about the digital.
Nowadays, all modern sound sources store material in digital form -- recorded in a studio, compressed using algorithms and translated into 0 and 1 of which a digital signal consists.
Any audio player has an analog-to-digital converter (ADC) which also, guided by algorithms, puts out the sound signal through the audio output, for example, headphones. Here we encounter the first problem: which ADC is installed in the audio device? If it is of poor quality then even well-recorded output material will be far from the original sound.
Most professional and semi-professional players have both a classic audio output and a digital one. Similarly, your receiver/amplifier has two inputs. When you use an analog channel, the sound is determined first of all by the ADC in the source, transmitted through the audio cables (another weak point that can distort the sound) and comes to the amplifier where this signal needs to be received, equalized and amplified. That is, the chain of converters complicates the signal delivery path and adds its adjustments to the final sound quality.
If you connect your signal source via a digital channel it delivers a signal in the form in which this signal is present on the digital channel, and in the same form it is received by your receiver/amplifier. If you are using quality equipment your receiver has a quality analog-to-digital converter and it already works with this signal directly. Additionally, a specific trait of digital signal is noise immunity -- such a signal either exists or not. It won't come out distorted.
So why do manufacturers keep offering an analog input?
There are several reasons here: for instance, if you are a turntable fan, then analog is your sound channel of choice. Or if you want to connect a source where there is no digital output the analog input of the amplifier will come in handy.
We have just figured out what analog and digital audio transmission channels are for and what the difference between is. Yet, some folks may still wonder about the difference between digital coaxial and digital optical inputs.
True, modern devices offer optical and coaxial digital channels. At their core, both coaxial and optical digital channels rely on the same algorithm of 0s and 1s. In the case of a coaxial transmission channel, data is transmitted over a two-wire cable in digital form. In the case of the optical channels, signal is transmitted by a beam of light, through optical fiber wires. Such light can be seen with a naked eye when the optical wire is unplugged, it usually has red color.
What then is the difference -- why not offer just one type of digital transmission?
A coaxial wire is still a wire -- and in situations when a long coaxial wire is used -- signal attenuation will begin inside of it and -- depending on the quality of the cable -- your receiver will simply have nothing to receive at a certain length. No doubt, such cables are cheaper, much easier to use and switch. As a matter of fact, you can take any RCA cable and it will work (even the cheapest one), if the distance from the sound source to the amplifier is not large.
An optical cable is a cable in which a special fiber is laid under the insulation which transmits light and does not scatter it. The length of such an optical cable can be much longer than coaxial and the signal strength (light power) will be sufficient.
Normally, optical cables are sold ready-made, with special connectors for audio equipment installed at the cable's two ends. This makes it challenging to shorten or lengthen such wires, calling for special tools and skills. The disadvantage of such a cable is its fragility. Optical cables can easily break, which renders them dysfunctional.
We hope that this article was useful to you, in the future we will still touch on the features of analog and digital signals, so watch this space!