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1

PRELIMINAR

Y

TECHNICAL

DA

TA

a

Circle Surround 5-Channel

Soundfield Generator

SSM2005

FEATURES

Generates True 5-Channel Soundfield

No Pre-Encoding Required—Only Stereo L and R

Excellent Surround Image At All Positions

Superior Sound in Automobiles

Distinct Left Rear vs. Right Rear, Full Bass Response

No Delay Required—Natural Ambiance Preserved

4 or 5 Speaker Operation

Full Bandwidth on All Channels

Optimized for Music Reproduction

Superior Decoding of Dolby* Surround Material

Excellent Decoding of "Pre-Encoded" Sources

Usable in Home Theater and Video Games

+7 V to +20 V Operation

GENERAL DESCRIPTION

tor produces a true 5-channel surround soundfield using only

standard unencoded left/right stereo sources. Left front, right

front, center, and differentiated left and right rear channels are

generated providing a realistic ambiance effect with either 4 or 5

speaker configurations. Unlike previous designs, Circle Sur-

round is optimized for music reproduction with full bandwidth

on all channels and proper separation of the front channels. The

differentiated rear channels provide excellent imaging, especially

in automotive applications. Listener position is not critical; well-

balanced sound is obtained anywhere within the soundfield.

The Circle Surround process does not require the audio

signal to be encoded, as it uses the ambiance and directional in-

formation already present in the original media to generate the

multidimensional effects. Circle Surround does not add any ar-

*Dolby is a registered trademark of Dolby Laboratories, Inc.

†Circle Surround is a registered trademark of Rocktron Corporation and

is protected by patents granted and applied for.

REV. 0

tificial ambiance or reverberation, nor does it require any delay

generators. The fully differentiated rear channels provide rear

stereo separation for enhanced spacial perception while main-

taining full bass response, especially important in automotive

applications.

CIRCLE SURROUND SYSTEM BLOCK DIAGRAM

OUTPUT

MATRIX

VCSs

& SWITCHING

STEERING

SIGNAL

GENERATOR

REFERENCE

GENERATOR

F

B

CROSSOVER

C

R

L

L+R

L–R

INPUT

MATRIX

CONTROL

LOGIC

STEREO/

SURROUND

CENTER

PHANTOM

REAR

STEERING

WIDE/NORMAL

TIME

CONSTANTS

(DOTTED BOX = EXTERNAL TO IC)

SSM2005

NOISE

SOURCE AND

SEQUENCER

OBSOLETE