Surround sound systems have evolved rapidly over recent years, and with all the different configurations available, it can be difficult to keep track of. However, by the end of this article, you will have a better understanding of what all those numbers mean and how to determine the optimal setup for your space.
Firstly, you may have encountered numbers like 5.1, 7.1.2, and so on. These numbers indicate the number of audio channels in a surround sound speaker system. The first number represents the number of primary channels, including left and right channels, center channel, surround channels, and wide and rear channels. One of the most basic configurations is the two-channel stereo, which consists of a left channel and a right channel. For the best results, the listener should sit to form an equilateral triangle between the speakers and the listening position.
As you add more primary speakers, the canvas is expanded so that sounds can appear to originate from all around you on a horizontal plane. The second number indicates the number of LFE (low-frequency effects) channels. It’s important to understand that these numbers represent the number of channels, not necessarily the number of speakers. For instance, in a 2.1 system, there’s a dedicated signal for the subwoofer.
With a 3.1 configuration, we add the center channel, which is probably the most important speaker for film sound, as most of the dialogue will come through that center channel. Another common format is the 5.1, where we have LCR channels (left, center, right), two additional surround channels, and an LFE channel.
The third number tells us how many overhead channels there are in the system. Overhead channels allow the listener to hear sounds from above, extending beyond just the horizontal plane. In a 9.2.2 system, there are nine primary channels, two LFE channels, and two overhead channels. The overhead channels can be played through speakers placed above the listener, such as a pair of ceiling speakers. Alternatively, the overhead channels can play through floor-standing or bookshelf speakers with up-firing drivers.
Dolby Atmos changes the paradigm from channel-based mixing to object-based mixing. Rather than routing the sirens to the left and the helicopter to the right, the engineer places each source in a virtual 3D space. Each sound source is considered an object and will be placed in the same spot when played back through any Dolby Atmos system, regardless of the physical configuration.
It’s important to maintain surround compatibility throughout the signal chain. For example, connections like HDMI and optical are capable of transmitting discrete surround channels, while stereo RCA connections only support stereo. It’s also important to adhere to the standards of speaker placement to ensure the best experience.
In conclusion, understanding the different configurations and maintaining compatibility throughout the signal chain will allow you to make all speakers work on surround sound. You can download a free speaker placement guide from audio audiouniversityonline.com to help you configure your system for the most common formats.