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To reproduce the movie theatre sound experience at home, today’s emphasis on home theatre surround sound necessitates new audio formats, receivers, and more speakers. One of the most significant differences between stereo and home theatre surround sound is the requirement for a dedicated center channel speaker.
Stereo and Center Channel Speaker
Stereo audio was meant to split recorded sound into two channels (the term “stereo” means “two channels”), with left and right channel speakers placed in front of the room. Although some sounds are only heard through the left or right channel speakers, the majority of singing and conversation is blended through both speakers.
The vocals are mixed to originate from both the left and right channels, resulting in a “sweet spot” that is equidistant between the left and right channel speakers. The voices appear to be coming from a phantom middle place between the left and right channel speakers, giving the listener the impression that they are emanating from there.
Although this is an effective way to present vocals, as you move your listening position from the sweet spot to the left or right, the position of the vocals will (or should) move with you, even though the dedicated left and right sounds stay in their relative positions dictated by the left and right channel speaker. The balance setting on a stereo receiver or amplifier can also be used to hear this effect. You can hear the vocals shift position as you adjust the balance control to the left or right.
As a result, because the vocals come from both the left and right channels in a standard stereo arrangement, you can’t alter the position or loudness (volume) of the centre channel vocals separately from the left and right channels.
Surround Sound with Center Channel Speaker
Surround sound is a good way to solve the centre channel problem that two-channel stereo listening causes. In contrast to stereo, a real surround sound configuration requires a minimum of 5.1 channels, with the following speakers assigned: front L/R, surround L/R, subwoofer (.1), and dedicated centre.
Sound is mixed into each of those channels in surround sound codecs like Dolby and DTS, including noises that are expressly intended for a centre channel. DVDs, Blu-ray/Ultra HD Blu-ray Discs, and some streaming and broadcast programmes support this encoding.
Instead of being placed in a phantom centre location, the vocals/dialogue are placed in a dedicated centre channel as a result of how surround sound is blended. The centre channel requires its own speaker due to its positioning.
Although the addition of a centre speaker adds a little more clutter, there are some definite benefits.
Changing volume levels:
Because the centre channel is distinct from the left and right front channels, its volume level can be modified without affecting the left and right front channels’ volume levels.
This is useful for compensating for either low or too high dialogue/vocals in a music or movie soundtrack because the volume coming out of the centre channel speaker can be adjusted independently of the other speakers.
Despite having its own “sweet spot,” surround sound offers a more flexible listening experience.
While sitting in the surround sound sweet spot is ideal, the vocals/dialog will still look to come from the centre position as you alter your listening position from left to right (although at an angle off-center from the sweet spot).
This is closer to how it would sound in real life if someone were chatting or singing in that location while you moved around the room…
Without a Center Channel Speaker, Surround Sound
If you don’t have (or don’t want) a centre channel speaker in your surround sound configuration, you may “inform” your home theatre receiver that you don’t have one by using its speaker setup options. When you select this option, the receiver “folds” what would normally be the centre channel sound into the left and right front main speakers, much like a stereo arrangement.
As a result, the centre channel lacks a designated centre anchor location and is subjected to the same restrictions as vocals and analogue in stereo settings. You wouldn’t be able to modify the volume level of the centre channel independently of the left and right front channels…
How Does a Center Channel Speaker Look?
You can use any speaker for your centre channel (except a subwoofer), but you should look for one with a horizontal cabinet design rather than a vertical or square one, like the one shown below from Aperion Audio. The reason for this is more cosmetic than technological. A centre channel speaker with a horizontal shape can be simply placed above or below a TV or video projection screen.
What Else Should a Center Channel Speaker Have?
If you’re replacing a centre channel speaker, try to get one that’s the same brand as your main left and right speakers and has a similar mid-range and high-end frequency response capability. The reason for this is that your ear should hear the identical sound from the left, centre, and right channels. “Timbre-matching” is the term for this.
If your home theatre receiver has an automatic speaker configuration system, it may be able to adjust utilising its equalisation capabilities if you are unable to find a centre channel speaker with identical characteristics to your left and right front channel speakers. Another alternative is to acquire a speaker system that includes the whole speaker mix—front left/right, surround left/right, subwoofer, and centre channel—if you’re putting together a basic home theatre setup from scratch.
It’s up to you whether you use a centre channel speaker if you’re upgrading from two-channel stereo to a full home theatre surround sound system, but here are some things to think about:
An audio anchor point is a speaker in the centre channel that serves as a distinct anchor point for speech and voices.
Adjust volume individually: A centre channel speaker’s volume can be adjusted independently of the other speakers in a system, giving you more options for adjusting the overall sound.
Invest in a speaker that works well with your other speakers: Consider a centre channel speaker with similar acoustic qualities to your left and right front main speakers while buying.
Consider a horizontal speaker: A horizontal speaker can be placed above or below a TV or projection screen and is preferably positioned at an equal distance from the front left and right channel speakers, allowing for optimal centre channel placement.