This Instructable describes how I built a surround sound system for use with a 3.5 mm stereo output. The goal is to extend surround sound experience from any 3.5 mm stereo headphone output with quality and simplicity. Works great with PCs, MP3 players, CD players, tape recorders etc. This is a low power (around 1 Watt) version of the ABC surround sound decoder.

You will need the following items to build 3.5 mm surround sound:
- Parts shown on attached schematic.
- Plugboard.
- 4 heatsinks (1.5" x 2" copper or aluminum sheet metal).
- 4 speakers (4 - 8 Ohm, about 3 Watt nominal power). Almost any type of speaker works:
Computer speakers, satellite speakers, small speakers, big speakers, etc.
- Wire.
- 4 phillips 6-32X1/4 nylon machine screws.
- 4 nylon 6-32 hex nuts.
- Heatsink grease.
- 12V, 500mA or more power supply.
- 3.5 mm plug to 3.5 mm plug cable.

Drill, solder gun and soldering accessories, cutters, tweezers, wirestripper.

Step 1: Making the Circuit

The circuit I used consists of a power amplifier with 3.5 mm jack input and the surround sound decoder. 3.5 mm input jack can be replaced by cable with 3.5 mm plug if desired.

Mark future hole center by placing T3 transistor at lower left corner of the heatsink. Drill hole in each heatsink.

Assemble circuit shown on schematic. This step requires some assembling and testing skills.

Apply a small amount of heatsink grease on T3, T4, T7, T8 transistors and secure heatsink on each of them using screw and nut. Warning: heatsinks should not touch each other!

3_5 mm ABC.pdf
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Step 2: Speaker Preparation

I used pair of low power Phillips speakers available at Walgreens and pair of old PC speakers.

Attach wires to each speaker paying attention on polarity.