Electronic Circuits and Projects Forum

Originally Posted by carloscapitao

Hy, I need circuit, diagram, schematic 5.1 decoder system.

I have surround theory, but with one surround channel output.

I want 5.1 sistem whit two surround channel output , Ls and Rs.

Dolby 5.1 is a digital system (used on DVD players and digital satellite receivers), presumably all you need is the correct I/C (and all the support components), for which you have to pay Dolby a licence fee.

I would have thought it's totally impractical to try and build one, you can buy DVD players and amplifiers with Dolby 5.1 built-in for very little money.

Originally Posted by carloscapitao

In dolby site there is all about surround sound system and because this
I could project, to build and to set up with success a prototype.

I sought information about 5.1 system but they are superfluous and I could not project an appropriate system.

I am sure that as soon as I discover the origin of the channels Sr and Lr I can project a circuit with great efficiency.

As far as I know they are simply individual channels in the digital data stream - which is why it can have two rear channels, and the analogue Pro-Logic can only have one.

Before I could afford a decent surround amp - in the days when even dolby surround processors seemed expensive (never mind pro-logic!) I connected a pair of speakers in series between the two 'right' output terminals of my amplifier's 'speakers b output'. i.e. nothing connected to the negative terminals.

I then switched the nicam and channel 'a' speakers off (mono sound, no front speakers) to balance the L+R channels until I could here minimum sound from the rear speakers. this was accomplished through VCR and amplifier balance controls.
This left me with rear speakers that only displayed left and right information and gave a very atmospheric surround effect! Surround sound which in my opinion was as good as the sherwood pro-logic amp I purchased a few years later!
I think that is possibly one of the more realistic approaches to making your own surround setup because as Nigel implied, Dolby are very protective over the technical details of their surround systems.
Even if you could get hold of the processors, making even a simple circuit would be no simple task!

Connecting the rear speakers in series and to both hot terminals of the stereo amplifier is The Hafler Method of cheap and simple surround sound. it was invented in the early 70's. I used it with vinyl records. Its front to back separation is very low but it is audible.

No speaky zee English?

Here you go! Good luck building one!