Building a 3.5mm 5.1 Surround Sound Switch / Splitter Box

I had a problem which needed solving.

I’ve just bought a Dell 2709w Monitor which takes DVI and has 5.1 output using the standard PC solution of three 3.5mm jacks, coloured Green, Orange and Black. I had hooked up my Xbox 360 via HDMI to the monitor, and the sound comes out of these (unfortunately only in Stereo since it’s in Dolby Digital, but that’s another story). This would be great, however there is no similar input, meaning that I have the issue that I had to keep swapping the jacks on my subwoofer if I wanted to get any sound from my PC or the Monitor. Having carried out much searching on the internet, I was unable to find a box that does this, and while many people seem to have similar problems, very few people have a solution.

My first test was to simply try a headphone splitter in reverse on each individual subwoofer channel. This didnt work, since the computer’s output always took presedence over the monitor’s output. It was then that I came across the following article on Bl3nd.com – 5.1 Audio Switch. It’s at this point that I decided to contact Joey Hazlett, the owner of the site to get some information and increase my knowledge on building such a device, with a mind to do it myself. I have to say that Joey was masses of help and the following guide wouldn’t be possible without him.

Joey’s guide was good, however in the UK I was struggling to find many of the parts. It was then I decided to use three switches to control each channed independently. So, here i a guide to building a box like I have now got…

Building a 3.5mm 5.1 Switcher Box

Basically, I needed to take two times three 3.5mm inputs, and send it to one three 3.5mm output. I ended up with this diagram (it’s rough, i know!)

G, O, B stand for Green Orange and Black, the three channels, and L, R, G stand for Left, Right and Ground. The things in the middle are three DPDT switches (Double Pole, Double Throw), which basically allow you to take two sets of 2 contact inputs and join them to an output.

Basically, all that happens is that you solder everything together and it works! The only thing that is tricky is making sure the wires all match up on the correct channels. The only place that this gets particularally difficult is on the 3.5mm socket. You need to look at this and work out which is which. On a 3.5mm jack, the tip is the left channel, the shaft is the right, so look at the connector and you can work out which point is which. Also, when looking at the switches, think of them as two sets of 4 points (with the middle 2 being in both set), and that each side of 3 is independent. When the switch faces one way, you are getting those 4 points connected, and when it faces the other, the other 4. This will help you to work it out. The rest is a doddle, if a little fiddly…

Finding the parts was a little tricky until I came arcross Rapid Online, and the parts i used are as follows:

In addition to the initial premise, I also decided to take a dual phono connector in. This was to allow my Wii to connect into the same box. I also wanted this to duplicate the front channels on the rear (with the option of turning the rear off). This in fact turned out to be the hardest part. A phono connector looks like this, with simply one wire and the ground coming out, so after buying some phono sockets from ebay and another DPDT switch from Maplin (although I’ll only use one side of it), I did the following

I had to split each phono cable into two – one for the back channel and one for the front. I then took the back channel ones (one from left (white), one from right (red)) and attached them to one side of the DPDT switch. The middle of the switch went directly to the back channel switch on the side of input 2 – this allowed for the breaking of the back channel for just this input. The reason I went to input 2 is because this is coming from the Monitor (i.e Xbox) and I will not be using the Wii and Xbox together. The other two leads went directly to the switch for the front channel.

Finally, every single one of the grounds was joined together in one big clump!

Once completed, everything is plugged in and works like a dream :)

Photos of the project are below.

If you have any queries about a similar project that you are doing, please feel free to contact me and I will do my best to help. Please e-mail me on surround-project at gambituk dot com

10 Responses to “Building a 3.5mm 5.1 Surround Sound Switch / Splitter Box”

  1. 1
    Wil Says:

    Thanks for this page please keep it up, as i assume i will have to be constructing up the same thing for a similar problem of two 5.1 inputs into a 5.1 system that only takes one input.
    Its so frustrating that there is no mass manufactured one of these, i thought it would be a relatively common problem!!

  2. 2
    Gambit Says:

    No problems Wil – i have no plans to take it down anytime soon, so it should still be here :)

  3. 3
    Wil Says:

    How bigger box would you recommend?
    What size did you use?

    thanks Gambit

  4. 4
    Gambit Says:

    My box is around 10cm Long, 7cm wide and 4cm high (off the top of my head). I think they come in fairly standard sizes, so look for the one that is 10cm long

  5. 5
    James Says:

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  6. 6
    Lanzarek Says:

    Wow, I can’t believe you can’t buy these anywhere. I’ve been looking for something like this, too. I was wondering if this would work in reverse (one input -> switch between two outs). I have a set of 5.1 headphones as well as a 5.1 speaker system, and even before ever having them both I knew there was going to be a problem..The idea was to use the speaker system for music and videos, and the headphones for gaming, but there’s no convenient way to change between them without messing with wires! It looks like I may have to build my own.
    Nice guide by the way!

  7. 7
    Gambit Says:

    I see no reason why you couldnt wire it up to work in reverse! There *are* however commercial solutions for that – far more common…

  8. 8
    pc satellite tv Says:

    pc satellite tv…

    Great information. I will surely drop by again soon….

  9. 9
    Yoav Says:

    i tried to contact you before…
    would you be intersted in building and selling me one of those?

    plsease answer my email – pacificasnake@gmail.com

  10. 10
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