Introduction: Surround Sound From Stereo

Picture of Surround Sound From Stereo

This instructable describes how I converted stereo into surround sound using my decoder and two satellite speakers. The goal is to extend "home theater" surround sound experience to any place with quality and simplicity. Works great with all stereo equipment including TVs.

You will need the following items to convert stereo into surround sound:
1 Surround Sound Decoder Kit
2 Satellite speakers (4 - 8 Ohm, about 3 Watt nominal power). Almost any type of speaker works: Computer speakers, satellite speakers, small speakers, big speakers, etc.
Cables to connect satellite speakers
Pliers, cutters, and heat gun to strip and terminate cables

Step 1: Choose Place for Satellite Speakers and Prepare Cables

Picture of Choose Place for Satellite Speakers and Prepare Cables

The satellite speakers should create a trapezoid, rectangle or square shape with the front speakers. Two short cables are needed to connect amplifier output with the decoder and two long cables are needed to connect satellite speakers to decoder.

Step 2: Terminate Cables

Picture of Terminate Cables

Strip 3/8 of insulation from the ends of all cables. Place cable end on the snap-on terminal, allowing 1/8 of insulation to reside within terminals tail. Fix cables end in place by squeezing the terminals tail around cables insulation. Squeeze terminals neck around wire with pliers. Bend excess wire toward the terminals tail. Attach terminals to all cable ends going to decoder. Mark cable ends with heat shrink tubes. Place red tube on + or red wire. Place white tube on - or black wire. Apply hot air to shrink the tubes. Snap-on terminals and heat-shrink tubes are included in the kit.

Step 3: Final Connection

Picture of Final Connection

Snap terminals to decoder using directions on the label. Connect other ends of cables to amplifier and satellite speakers, maintaining proper polarity for all connections.


jaxboy (author)2012-08-12

The center channel can be created by simply running a wire from the + terminal of the 2 front speakers to the terminals of the center channel speaker. The same could also be done for the rear speakers. This causes only a slight reduction in volume.

rb118 (author)2010-06-24

This is cool! What about center channel?

RRC (author)2009-05-09

Got chance to hook up ABC surround sound to High-end system, everyone was impressed. No digital system can beat it up for linearity.

computer_freak_8 (author)RRC2010-05-28

What do you mean? Digital systems are inherently more linear than analog; besides that, the sound you hear is analog, whether or not the processing equipment is digital.

RRC (author)computer_freak_82010-05-29

Spurious free dynamic range of digital to analog converter the major linearity limitation for digital processing (guess why there is significant price difference between digital systems). Passive ABC decoder will over-perform any active analog/digital one.   

Gooru (author)RRC2010-05-31

"Spurious free dynamic range..."??? Do you make this up as you go along?

computer_freak_8 (author)Gooru2010-06-01

No, RRC is using real terminology. It's just not anywhere close to being used properly.

Gooru (author)computer_freak_82010-06-01

My apologies... I didn't make myself clear.  "Spurious free dynamic range" is a valid term when dealing with the fidelity of an analog to digital conversion (not DAC as RRC suggests).  It has absolutely nothing to do with this particular circuit.  There is nothing "digital" about it, and using the term here is a smoke screen. 

RRC (author)Gooru2010-06-02

 Let me remind that conversation was started from digital linearity versus ABC (passive) linearity. There is a significant difference between performing surround sound math using digital circuitry and analog (particularly passive), in case of digital processing it is much harder maintain linearity. 
DAC also has linearity issues, output signal contains steps producing very rich spectrum falling into audible region. Steps unfortunately is not equal creating even more harmonics (spurs).  

Gooru (author)RRC2010-06-18

More smoke....

I stand corrected: "Passive ABC decoder" is not a real term. At least, if it is, then Google is running behind...

RRC (author)Gooru2010-05-31

This is a basic concept of digital audio processing, study it to understand or just enjoy.

computer_freak_8 (author)RRC2010-06-01

What is a "Passive ABC decoder", other than a term you invented?

RRC (author)computer_freak_82010-06-02

 Passive means all additions and subtractions are performed using passive (resistors) components.  

computer_freak_8 (author)RRC2010-06-02

Yes, I know what "passive" means, and I know what "decoder" means; but I cannot find anywhere that there is a type of decoder that's passive and known as an "ABC" variant.

Others following this discussion: run a Google search for "abc passive decoder", "passive abc decoder", or "abc decoder circuit". The quotes are needed for it to search for the phrase (rather than just containing all three on the same page).

I still can't find any, which leads me further to believe that this is simply a Hafler circuit (or some variant thereof) in a box, and thus incapable of "decoding" anything apart from the difference of the left and right channels.

To RRC: So, how do I make a sound play on the one of the rear speakers, but not any of the other three, via this Instructable?

RRC (author)computer_freak_82010-06-02

You should use different language and search engine for ABC surround sound.

Hafler circuit is incapable of decoding more than left/right difference since it does not have weighting.

You can get discrete sound from rear speaker by proper encoding. Encoding method is beyond this instructable. 

I have shared simple quality surround sound from stereo method, this instructable is good for someone handy to connect wires, while another instructable is good for someone willing to build from schematic.  

Gooru (author)2010-03-27

Sorry, but this is "pseudo" surround sound.  If you want to see how the really works, look for the article titled "Simulated Surround Sound".

RRC (author)Gooru2010-03-28

This is true 360 degree surround sound system with appopreate recording.
It acts as 180 degree surround sound for regular stereo and x.1 formats.  

Gooru (author)RRC2010-05-25

No sir, it is not "true 360 degree" sound.  That requires at least one and preferably two discrete signals for the rear channels.  With your setup, some component of the left and/or right signal will always exist in the other channels.  At best, this device will widen the stereo field, but it can never derive a discrete sound source from the existing two channels of audio.

RRC (author)Gooru2010-05-29

Any surround sound system has processed components cross penetration.

As I mentioned before appropriate recording (incoding) will create two rear discrete sound sources. Any surround sound system creates 360 degree only with matched incoding/decoding.

Proposed system creates 3 stereo zones covering 180 degree for regular stereo and x.1 source formats. 

computer_freak_8 (author)RRC2010-06-01

This makes no sense whatsoever. If it is encoded, it will require decoding. Like you said, "set of formulas". Very ambiguous; not useful for me to know how I need to "encode" my audio to have it "decoded" by this Instructable. Probably because it doesn't really "decode" anything, (at least not in the sense that I normally hear that word used) other than what's already there: the stereo signal. It's not like it carries any "extra" data, is it? Is this device compatible with four discrete channels? If so, please correct me.

Since your device is passive, my guess is that it's simply a Hafler circuit, no?
For others following this discussion, look here and here. If I understand correctly, RRC's box is simply a pre-wired Hafler circuit (or a variant thereof). Essentially, it would me the "rear" channels are just the difference of the left and right stereo ("front") channels.

RRC (author)computer_freak_82010-06-02

 You don't need to encode anything it is already done (stereo, x.1 etc.) by record companies unless you want to get whole 360 degree out of ABC decoder. Half of the formulas is used during recording, second half is implemented inside ABC box. Encoding (any type: stereo, x.1 etc.) by record companies is good enough for ABC, well, sound sources will not be in exact place (they are not in exact place even with Dolby due to listener position and speakers constellation). 
 In general each surround sound system has signals from the front speakers in the rear speakers to simulate reflections from the walls.
 I'm using ABC since 1982, ABC decoder schematic is presented in my instructables "Surround Sound from 3.5mm stereo".
 Hafler's circuit suffers from having non-weighted channels difference in rear speakers (reflected from the wall signal cannot have the same level as original signal).  

computer_freak_8 (author)RRC2010-05-28

Two questions:
1. What do you mean by the appropriate "recording"?
2. What encoding does this device "decode"?

RRC (author)computer_freak_82010-05-29

1. Appropriate recording processes signals from microphones to insure creation of discrete rear sources during decoding.
2. There is the set of formulas for encoding and decoding.  

HarleyDK (author)2009-08-10

I once saw a schematic of a 5.1 surround processor, and there the rear fill was the difference in output on front-speakers, so you could just use an amplifier with common negative, and hook the rear fill up in parallel to the positive output from your amp. I have used the system myself, and got a pretty good sound impression when I first saw T2

srhadaham (author)2009-07-26

so does it have the proper delays that surround sound uses to create depth?

RRC (author)srhadaham2009-07-27

Yes, it creates depth by using other than delay method.

About This Instructable




Bio: Electronics expert
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