When you think of home audio, you might imagine listening to music using streaming services like Spotify or Amazon Music, or perhaps using your CD player or vinyl record turntable. For some, home audio is all about entertainment through the TV. Regardless of how you view home audio, we all know that we need a speaker to produce the sound. This speaker is the physical device that moves the air in rhythm, and this change in air pressure is what our ears perceive as sound.
In the gif above, I am attempting to show you all the major components that go into reproducing audio for you. In the market, you can source all the components built into one device, a combination of features in a device, or individually source all the components with separate devices.
Now let’s dig into the components to understand their function in reproducing audio.
Audio Source
When you hear audio at home, it is coming from a stored source of audio. Audio can be stored in two different formats: Analog and Digital.
Digital Format: This is the new technology where audio information is stored in combinations of 1s and 0s. Common examples include streaming sources like Spotify or Netflix, CDs, DVDs, and Blu-ray.
Analog Format: This is the old-school way of storing audio. Examples include cassette tapes, vinyl records, and VHS videos.
| Analog Audio Source | Digital Audio Source |
| Theoretically more information is stored in this format, but with less signal-to-noise ratio. | Some information is lost when encoding audio into digital format, but high resolution can ensure the lost information is beyond human hearing capability. |
| Low storage density. A vinyl disc can hold approximately 20 minutes of audio on one side. | High storage density. A CD can store hours of music and is much smaller than a vinyl disc. |
| Enthusiasts say analog sounds more natural. | Digital audio can be sterile or clinical. |
| Sound is analog when recorded and reproduced. | Sound is never digital; it is converted to digital for storage and manipulation. Eventually, it has to convert back to analog for humans to hear. |
Pre-Amplifier / DAC
The job of a pre-amplifier or DAC is to convert the audio source signal to an analog line signal for an amplifier. This output can contain volume information for the amplifier but not necessarily always.
- Analog Source: You have to amplify the signal received by the media reader to a line signal. For example, in a vinyl record player, a phono cartridge converts the small grooves on the vinyl disc into a small electrical signal. We then feed that raw signal into a “phono preamp” to boost the signal to a line signal. In this example, no volume information is available in the phono preamp output.
- Digital Source: This kind of source needs to first convert from digital to analog signal using a DAC (Digital to Analog Converter). The output of the DAC is then pre-amplified to line voltage. For example, your CD player will have a DAC that converts digital bit info on the CD to an analog signal, which can then go to an amplifier as a line signal. The same is true for your smartphone.
The output of a pre-amplifier/DAC will be either balanced or unbalanced. Balanced cables have three wires and are better at suppressing noise induced by long cable lengths, while unbalanced cables have two wires and if noise gets into the cable, it will show up in your audio signal. For home use, the length of cables is short, and the electronic noise in your house is too small to see a difference in the signal. Examples of balanced cables are TRS and XLR cables, and examples of unbalanced cables are RCA and 3.5mm audio cables.
Learn more about the difference between balanced and unbalanced from this external blog.
Amplifier
The job of an amplifier is to boost the line-level signal to a signal that is powerful enough to drive a speaker. The power needed by the speaker to produce the desired sound varies based on speaker size, components used, and design. Amplifiers usually boost the line-level signal about 20 times.
Amplifiers are rated by watts delivered per channel (at a given speaker impedance). For example, you can buy an amplifier that does 20W per channel impedance vs. an amplifier that does 100W per channel.
Please note that an amplifier’s power rating is based on the speaker impedance value. For example, a Crown XLS1000 amplifier is rated for 215W (watt – unit of power) at 8Ω (ohm – unit of impedance) but is rated for 250W at 4Ω.
If you want to learn more about the relationship between speaker impedance and amplifier power please refer to this external blog.
Speakers
Speakers are the end device that reproduces the audio into real sound that humans can hear. They come in many shapes and sizes. In the picture above, I am showing examples of popular speaker types you will see in the home audio space.
- Bookshelf Speaker: The most versatile speaker type. It can be used for anything from reproducing music from your vinyl recorder to your TV.
- Floor Standing Speaker: Used in a larger room to fill the whole room with sound.
- Center Channel Speaker: Specially designed to be placed between two speakers for reproducing dialogues from the center while watching TV.
Speakers can also be broadly categorized as passive and active speakers. Passive speakers need an external amplifier to power them, while active speakers have an amplifier built into them. Some modern active speakers will also have a DAC and pre-amplifier built into them as well.
In the home audio world, you can have anywhere from one speaker (standalone Bluetooth speaker) to a combination of 11 speakers (Dolby 5.2.4 setup) and more.
Conclusion
To reproduce audio that was recorded in the past, you need a medium in which the audio is stored. In this article, we call this an audio source. We need to use an appropriate device to read this signal and convert it into a line signal using a DAC and/or pre-amplifier. This line signal then needs to be amplified into a speaker-level signal and then fed to a speaker to reproduce the audio.
Home audio is a field that allows you to buy one device that does everything for you to start enjoying the audio, or you can get into a rabbit hole where you are obsessed with sourcing individual components and fine-tuning their output to meet your home requirements.
Please note that we have only touched on the active components needed to reproduce audio. There is a whole passive component in perfecting audio reproduction, which involves room treatments and speaker placement techniques that can influence how sound is propagated in your listening area.
In the comment section below, please share your journey in home audio and don’t hesitate to ask any questions that you may have in this space.
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