Surround Sound Decoder

Small Surround Sound Decoder

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�� Surround �� , �� . �� . � �� Stereo Dolby Surround �� DTS, Dolby 5.1 �� , �� . �� .2 �� surround �� Lch �� IC1A �� Rch �� IC1B, �� . �� [IC2C], � �� L+R �� [IC2D], �� L-R �� , � �� . � �� IC2D �� . �� IC5, �� 512 ��. � �� IC5 �� IC4, �� . � �� C17. �� , �� 8KHZ �� 100 �� , �� . � �� 100�� 8��, �� . �� IC6A/B, �� . �� (��), �� . �� 15V.

The particular circuit does�t have the requirement to replace the trade decoders Surround, because this they have many more facilities and possibilities. It give however the possibility in many try with this article of decoding. The coding in Stereo Dolby Surround show the tendency to be abandoned and is replaced with digital DTS, Dolby 5.1 etc, that is supported in the digital level of management and transport, sound signal. In order that appears also in the Fig.2, the stereo sound signal that transport the surround information, is drive for the Lch in the IC1A and Rch in the IC1B, that is input buffer with the next stages. Then follow the stages of summing [ IC2C ], which add up the signals of channels L+R and him drive to the output for central loudspeaker and a differential amplifier [ IC2D ], that rise the difference of phase L-Rch with which is written in the two channels, the information for Rear loudspeakers. The exit of IC2D drive one regulated delay unit of sound to Rear loudspeakers, so that are created the sense of space and her adaptation in the size of our own room. It�s constituted by the IC5, that is a opamp. sound delay signal of 512 stages. The timing of IC5 becomes from the IC4, that is a oscillator. The delay time is regulated by variable capacitor C17. In order to we cut the noise that is produced by this process exist certain filters then, regulated they cut the frequencies above 8KHZ and under 100 HZ roughly, after we behind did �t need bigger frequencies bandwidth, to drive the Rear loudspeaker. The Rear information is written with bandwidth of 100HZ until 8KHZ, for this reason Rear loudspeaker has small size. These filters are found round the IC6A/B, that is output buffer, too. In all the outputs exist potesometer that help in the right level regulation of amplifiers and loudspeakers, that follows. Obvious it�s that each exit should drive single power amplifier .The circuit is supplied by symmetric voltage � 15V.

	Part List

R1-2-7-8-12-13-18-19-20=47Kohm	C11-12-15=10uF 25V	RV1-RV2=2X10Kohm Log. pot.
R3-4-5-6-21-22-34-35=10Kohm	C13=82nF	RV3-4=10K Log pot.
R9-10-11-14-15-16-17=15Kohm	C16=18pF 100V	D1=1N4148
R=23-24-25-33-36=100ohm	C17=100pF mini adjustable capacitor	IC1-6=TL072
R26-27-28-31-32=100Kohm	C18=2.2nF	IC2-3=TL074
R29-30=5.6Kohm	C19=4.7uF 25V	IC4=MN3101
C1-8=47uF 25V	C20=100nF 100V	IC5=MN3004
C2-7-9-14-23=47nF 100V	C21=10nF	JI.....J6=RCA female jack
C3-6=1uF 100V	C22=180pF
C4-5-10=33pF 100V	C24=150nF

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Sam Electronic Circuits 5/02

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