Sound Cards - CompTIA A+ 220-1101 – 1.18

Let’s have a look at how sound is produced in a computer and how sound cards work. It is unlikely you will get an exam question on the information in this video, so this information is aimed at helping you configure and support sound in your organization.

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PC Speaker
I’ll start by doing a quick history lesson. The first personal computers had a large speaker, referred to as the PC speaker. It allowed the computer to make basic sounds like beeps and basic music. Since there was only one PC speaker, it was limited to mono sound. Back in those days the PC speaker was very CPU intensive to operate. More on that later in the video.

In modern computers, the PC speaker has been shrunk down. Its purpose in modern computers is to make beep sounds when the computer starts up to indicate everything is o.k. or that there is an error.

Thus, although the PC speaker is only used nowadays for making beeps, these beeps are very valuable when something goes wrong with the computer and you need to troubleshoot what is causing the problem. Nowadays, the vast majority of motherboards come with a sound chip embedded on the motherboard which provides superior sound quality over the PC speaker. You may want to replace this embedded sound chip with a dedicated sound card; however, to know if this will meet your needs there are a few things to understand first.

Digital To Analog (DAC)
The first thing to consider is Digital to Analog otherwise known as a DAC. A DAC converts a digital signal to an analog signal. To understand this process better, consider that you have a digital signal entering the DAC. This digital signal at some stage originated from the CPU. Nowadays, in most cases, the sound mixing is performed by the CPU. In order for humans to hear the sound it needs to be played through some speakers; however, speakers don’t work using digital signals; they work using analog signals. Thus, it is the DAC’s job to convert the digital signal to analog so that it can be played on a speaker.

The DAC will support one or multiple resolutions. This is essentially the number of possible levels it is designed to reproduce. This is generally defined in bits. The higher the number of bits the better quality the sound will be; however, as the number of bits increases, it gets harder to notice the difference.

The point to remember is that a digital signal needs to be converted to analog somewhere. If this occurs in a location where there is electrical interference, this interference will be heard as noise in the speakers. So now we are starting to understand one of the first things to consider if you are planning on purchasing a sound card rather than using the embedded sound chip on the motherboard. That is, the location of the DAC and is it subject to interference in that location.

Prime Z490M-PLUS
Let’s consider an example motherboard. This motherboard has an embedded sound chip on it like the vast majority of motherboards do nowadays. Even though it is a chip on the motherboard, you may hear it referred to as a sound card. In the early days of computers motherboards did not have embedded sound chips and thus to have good sound quality, a dedicated sound card needed to be installed. Therefore, sometimes a sound chip may be called a sound card because they are used to using that terminology.

In the old days, motherboard manufacturers did not put much thought into where these chips were put on the motherboard. Thus, if the chip was placed near an electromagnetic source, it would be subject to interference. Interference can be heard as background noise such as the sounds you are hearing now. When the computer is under load the noise may change as electromagnetic sources in the computer also change under load.

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References
“The Official CompTIA A+ Core Study Guide (Exam 220-1101)” pages 29 to 30
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