Surround Sound Decoder

The following schematic diagram is a small surround sound decoder circuit. You may use this decoder surround sound systems for your home audio system to make the audio system sound more “alive”.

Surround Sound Decoder circuit diagram

Parts List:

C1-8=47uF 25V
C2-7-9-14-23=47nF 100V
C3-6=1uF 100V
C4-5-10=33pF 100V
C11-12-15=10uF 25V
C16=18pF 100V
C17=100pF mini adjustable capacitor
C19=4.7uF 25V
C20=100nF 100V
RV1-RV2=2X10Kohm? Log. pot.
RV3-4=10K Log pot.
JI…..J6=RCA female? jack

How the circuit works:
The circuit’s operation starts as the stereo sound signal transports surround sound information on the master volume part of the circuit. This will drive the Left channel Lch attached to Model TL072 IC1A and IC1b in which Right channel Rch is attached. The outputs on these operational amplifiers would serve as the input buffer to the following stages of the circuit. IC2C is responsible for summing up the signals from the left and right channels that will power the central loudspeaker output while IC2D is responsible for increasing the phase difference between left and right channels which is encoded in the two channels and will be fed to the rear loudspeakers. It is necessary to ensure that the negative terminals between the rear speaker is not earthed because they will simply function in parallel with the main speakers.

The output of IC2D will power regulated delay unit of audio to the rear loudspeakers. This would lead to the creation of proper sense of spacing in accordance to the size of the room. This will incorporate op-amp sound delay signal IC5 MN3004 which has 512 stages. Since IC4 MN3101 is a clocking signal, it provides timing to IC5 as it functions as an oscillator in the circuit. Variable capacitor C17 regulates the delay time in the circuit. The presence of filters in the circuit is for the purpose of preventing noise that will be produced during the process. These filters can be regulated to cut the frequencies above 8 KHz and under 100 Hz, to be able to drive the rear speaker. The rear loudspeaker is small in size because its input is encoded with a bandwidth of 100 Hz up to 8 KHz. The filters are built around the IC6A/B which is also an output buffer. A potentiometer is placed in every output to aid in the adjustment and regulation of loudspeakers and amplifiers. The supplied power in the circuit is 15 V and every output can drive a single power amplifier.

Surround Sound Decoder circuit

3 thoughts on “Surround Sound Decoder

  1. The decoder features an analog time delay, implemented with several cascaded all-pass networks and it improves sound system quality by eliminating out-of-phase information.

  2. Surround sound is a technique for enriching the sound reproduction quality of an audio source with additional audio channels from speakers that surround the listener (surround channels), providing sound from a 360? radius in the horizontal plane (2D) as opposed to “screen channels” (centre, [front] left, and [front] right) originating only from the listener’s forward arc.,

Leave a Reply

Your email address will not be published. Required fields are marked *