What Is A Surround Sound Processor

Stereo systems that come with different types of speakers and presets can have interference with the different types of audio/video processing, volume levels, and sound formats. A surround sound processor is basically the brain of the sound system. It decodes the different sound formats and volume control. Some of them are basic, but others which are more expensive can be updated with new software to keep up with new technology.

How does a surround sound processor work

Surround sound processors essentially decode different audio formats and multiple channels from different audio/video sources. Common formats such as Dolby Digital or DTS have the audio data packed into a single channel of data referred to as a bitstream, which needs to be decoded for the correct sound to reach each different speaker.

The sound processor is also able to calculate a surround sound input for a lower number of speakers and split it between a higher number of speakers. For example, if a bitstream for five speakers is inputted but the system has seven speakers plugged in, the surround sound processor can divide the sound so all seven of the speakers will output the correct sound.

Commonly, audio formats are only really shown to the average person in the beginning of movies. Widely recognized formats are Dolby and DTS.

Dolby Digital

This type of format was originally released on Laserdiscs, and then became more mainstream when it was used for DVDs. It can support from only one channel, all the way to six different channels. Each channel of digital sound can function independently. The arrangement for this format includes: Low Frequency Effects (LFE), Front Left (L), Front Center (C), Front Right (R), Rear Left (LS), and Rear Right (RS). Dolby Digital uses algorithms to include and eliminate different sounds in the bitstream to produce exceptional sound. Today, almost every sound processor includes a decoder with Dolby Digital.


This format, also known as Digital Theater System, was invented for theaters but has also found its way to home theater systems. The compression is less than Dolby Digital with only a 5:1 ratio. There are some people who think that due to the lower compression with this format the sound output is better than Dolby Digital, but since the codecs are different, the bitrates can’t be compared fairly.

What is a processor in home theater

The first sound processors for surround sound were used in theaters. As home theaters gained popularity, people realized that the normal sound system did not give the same experience as surround sound and looked for something more substantial to satisfy their audio needs for viewing at home. In order to upgrade to a surround sound system however, they needed the same technology that was used in theaters; the sound processor. Since then, the surround sound processor coupled with a receiver has become the central hub of home theater systems.

What does a sound processor do

Now that we’ve understood what a sound processor is, let’s look into what it actually does. It can perform several functions which may be necessary to have a new or upgraded sound system functioning optimally.

Sound equalization

Many times, stereo systems (especially in vehicles) have lower quality speakers and use equalization to make them sound better. Equalization, also known simply as EQ helps remove imperfections in audio by adjusting volume level, frequencies, and other options for modification.

Summing music back into a single channel

Factory audio systems generally divide the signal for audio for the speaker sizes in the sound system. If speakers are upgraded, a new sound processor can combine the signal back into a single channel and equalize the audio so it’s optimized for each speaker.

Adding digital delay

Sometimes if the sound leaves the speakers at the same time and they’re placed different distances from the person listening, the sound arrives at different times which creates a less optimal listening experience. The sound processor can delay sound coming out of a speaker closer to the listener so that it arrives at the same time as the sound from a speaker farther away.

Customizing sound going to each speaker

High quality sound processors are able to equalize the sound going to each individual speaker, increasing the sound quality coming from each individual speaker.

Sound processor brands

There are several sound processor brands out there, each with their advantages and disadvantages for their price points. Here are a few brands that have made a name for themselves in the audio world:


Rotel is a brand that’s been around the audio world since 1961 and has consistently produced quality products. It has won a few Best Buy awards for its line of sound processors. It’s a family owned company based out of Japan that specializes in audio and video equipment. Rotel prides itself on having products with life cycles which outlast their competition. They cater towards people who have an emotional and equipment investment in high quality audio.


Emotiva aims to deliver high quality products at an affordable price. The company is a collection of product specialists, enthusiasts, and engineers running a lean organization which is able to produce affordable products.


Trinnov processors are installed in some of the world’s most advanced audio and video production and viewing equipment. One of the most notable partnerships is between Trinnov and Harman International.

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