Other Sources, “Height” Channels and Other Formats

Posted by Eric on 5/9/2014

Matrixed Surround Decoding for Older Units

If you use a stereo analog connection to your receiver, or are connecting older equipment like a VCR, your receiver may employ one of two types of processing to decode the signal. Dolby Pro Logic II includes two independent full-bandwidth surround channels, three matrixed surround channels, and a dedicated low-frequency channel for your subwoofer. Many recent home theater receivers also offer Pro Logic IIx processing, which can turn the same sources into even more fully enveloping 7.1-channel sound. Receivers with Dolby Pro Logic II and IIx provide extra intensity to the thousands of VHS movies and TV broadcasts recorded in either stereo or older 4-channel Dolby Surround. They also include special modes tailored to turning stereo music into realistic surround sound.

"Height" Channels

A few receivers offer a newer surround sound format called Dolby Pro Logic IIz. It adds two "height" channels to your front soundstage. These speakers typically mount on the wall above your existing front left and right speakers. A receiver with Pro Logic IIz can divide up the front soundstage audio. It sends directional sounds, like a car that is racing by, to your regular front speakers, and non-directional sounds, like the roar of a crowd at a stadium, to the height channels. The result is a larger, deeper front soundstage, and a more immersive experience.

When Your Receiver has Other Surround Formats

Sometimes manufacturers will put their own special processing in a receiver, often called Digital Signal Processing (DSP,) in addition to the formats described above. Many home theater receivers use Digital Signal Processing to create sound fields, which are simulated acoustic environments, like a concert hall or stadium, and for precise steering of multichannel soundtrack information. This feature may go by different names, depending on the manufacturer.