User Manual

Multichannel Monitoring Tutorial Booklet (M2TB) rev. 3.5.2

Masataka Nakahara : SONA Corporation

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1-2-1. 3-1 ch

This method is based on a two-channel system (L, R), and adds a center channel (C) and surround

channel (S).

Although there are two surround speakers, one each at left and right, the playback is monaural.

The “3” in “3-1” indicates L, C, and R, and the “–1” indicates S.

Note that if “3-1” is expressed as “3.1,” this means “L, C, R” + “LFE” .

1-2-2. 5.1 ch

This method is based on the 3-1 ch system, but changes the surround to stereo (LS, RS) and adds an LFE

(Low Frequency Effect) channel for low-frequency effects.

The LFE channel is played back through a dedicated subwoofer designed for low-frequency playback.

1-2-3. 6.1 ch

This method is based on the 5.1 ch system, and adds a new back-surround channel (BS).

If two speakers are provided to play back the back-surround channel, these are sometimes called BSl and

BSr, but the signal that is played back is a monaural signal where BSl = BSr.

1-2-4. Other

As other formats, there is 3-2 (without LFE) and 2-2 (without C and LFE), which are based on 5.1ch but

do not use specific channel(s) of them

As a format with a greater number of channels than 6.1ch, we have 7.1ch.

7.1ch can be subdivided into the SDDS format which is used in film, and Dolby ProLogic IIx which is

used in DVD-Video etc.

SDDS is a discrete 7.1ch format which adds LC and RC channels between L and C and between R and C

respectively, and is used in applications such as supplementing the center gap between screen speakers in

large movie theaters. Since the 7.1ch SDDS format is compatible with 5.1ch, we can say that SDDS

supports both 5.1ch and 7.1ch configurations.

Dolby ProLogic IIx uses matrix logic processing within the decoder to stereoize BS (BSl, BSr), and at

present is targeted for surround processing in the playback system of consumer decoders (receivers).

Current multi-channel systems were developed to maintain compatibility with previous systems, and have

not been researched or developed in order to reproduce a 360° virtual acoustic space.

This means that if you expect current multi-channel systems to deliver full virtual acoustic playback

capability, you will be at your wits end. In particular, sound images directly to the side (the phantom

sound image of L and LS, or the phantom sound image of R and RS) are difficult to portray with current

speaker configurations, due to the physiology of hearing.

The key to multi-channel production is how to make effective use of the newly-obtained channels to

create a product with the maximum “entertainment value.”