From basic 5.1 Dolby Digital speaker solutions to full-blown 11.2 ATMOS systems that offer the latest object-based 3-dimensional sound, home theatre sound options are staggering! Read on to explore the possibilities.
Surround Sound History
The 1974 blockbuster disaster movie Earthquake—In Sensurround, audiences experienced bone rattling bass, forever sealing the equal importance of sound into an immersive movie experience. Later, four channel Dolby Stereo was featured in the 1975 block-buster film Star Wars. But this was not the first surround sound. Walt Disney’s 1940 movie Fantasia featured the 54-speaker Fantasound system; the first application of surround sound in a commercial theatre!
In 1982 Dolby Laboratories introduced its first surround technology for home use. Surround sound has since evolved in today’s “object based” Dolby Atmos & DTS:X formats, offering truly 3-dimensional big-theatre sound quality in studio-master audio resolution.
Modern Surround Sound
To deliver modern surround sound content, movie audio is encoded digitally, often with multiple types of CODECs, which then must be decoded and converted back into discrete channels of audio information by your home theatre equipment.
Broadcast TV content is almost always encoded in basic 5.1Dolby Digital surround. Blu-ray discs support the most and the best quality audio formats. Video streaming services have advanced surround like ATMOS, but they compress data to send it over the internet, so it typically will not sound as good as the same audio content found on a Blu-ray disc.
Sound Bars vs. Component Home Theatre Systems
While some premium Sound Bars decode advanced surround sound like Atmos, most Sound Bars offer only 5.1 Dolby Digital surround, and maybe a few “virtual” options. These systems typically combine the left/right/center channels into the Sound Bar, and may have two separate rear surround speakers, plus a powered sub woofer for bass .
For a fuller surround sound experience, a component home theatre system is required. These typically consist of a speaker package and A/V electronics that combine all of the control, processing, audio/video switching, and amplification for powering up to 13 separate speakers. Premium models support a wider variety of decoding than Sound Bars and often including advanced surround formats such as ATMOS and DTS:X. AVRs also offer microphone calibration (room-correction) to tune the system to the acoustics and speaker layout. Calibration options are not generally offered in today’s Sound Bar systems, and never to the same extent as in an AVR-based set up.
When an AVR Upgrade is Required
While this series is about mostly about audio, it is important to know that not only has the types of surround sound technologies become increasingly more advanced, video resolution and processing has changed too. Older AVRs may not have the inputs and/or decoding to be able to accept the newest high resolution audio and video formats.
HDMI standards have changed 6 times since inception! This means some HDMI cables will not be capable of passing these higher quality signals properly, if at all. For many with existing systems, upgrades are often required to experience the newest home theatre technologies, or when changing to today’s 4K & 8K Televisions.
Audio Video Receiver Types
Basic Surround Sound 5.1 AVRs
5.1 AVRs have speaker outputs for left, right, center, rear left & right surround speakers, plus a RCA type output for the (.1) Powered sub woofer.
7.1 Surround Sound AVRs
7.1 AVRs adds two more left/right “surround back” speakers for a more immersive sound field.The AVR can process 7.1 content or expand 5.1 content to include the extra speakers.
5.1.2 Atmos/DTS:X Surround
Some 7.1 AVRs support the newest Atmos and DTS:X processing. The two extra amplifiers are used with one pair of ceiling or height speakers in a 5.1.2 configuration instead of using surround back speakers.
Alternatively with a 5.1 theatre system, the 7.2 AVR’s two extra channels can also be assigned to a B-channel, or a 2nd zone (independent source and volume control), or assigned to Bi-Amp the front main speakers for improved sound, when speakers offer bi-amping and bi-wiring capability.
9.2 & 11.2 Surround Sound AVRs
9.2 & 11.2 AVR systems allow you to use 4 ceiling or height speakers for Dolby Atmos and DTS:X. These systems can be configured as 5.2.4 with up to 2 individually managed sub woofers. Alternatively these can be configured for 7.2.2 offering 7 surround speakers plus 2 ceiling/height speakers.
Most 9.2 AVRs also offer than ability to add an external 2-channel amplifier to expand to 11 channels so a full 7.2.4 can be enjoyed.
Like 7.2 AVRs, the unused channels in more basic surround sound configurations can be re-assigned to bi-amplify front speakers or to power speakers located in other multi-room “zones”.
5.2.4 Atmos/DTS:X Surround
11.2 AVR Separates
For the ultimate in surround sound, the A/V processor and power amplification are separated. The audio quality of separates is generally superior to most AVR’s and the amplifiers often offer greater power and current delivery to the attached speakers. Some of these A/V electronics systems offer 11 amplifier channels in the power amp box. Other combinations offer 2, 3 or 5-channel amplifiers for a virtually infinite combination of powering options. These types of home theatre electronics are typically reserved for the best home theatre and dedicated media rooms.
7.2.4 Atmos/DTS:X Surround