3.5mm 5.1 Surround Sound Switch / Splitter Box





Introduction: 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.

So, I was going to build a splitter box which takes two 3 x 3.5mm Inputs and allows you to switch between them to one similar output.
This would be suitable for connecting two 5.1 surround sound PC cards / PC's to the same subwoofer.

Step 1: Tools and Parts

To complete this project you will need the following tools:

Soldering Iron
Insulating tape
Drill and various sized bits
Stanley knife

You will also need the following parts:
Speaker Wire (I already had this)
1 x Box
9 x 3.5mm Sockets
3 x DPDT Switches

Thanks to Rapidonline.com for the parts - I really struggled to find these in the UK!

Step 2: Designing the Circuit

Initially, I wanted to do ths project with a single switch, but after not being able to find one big enough, I decided to separate the channels out. This turned out to be a better solution anyway, since i can have two different audio sources on at the same time.

So, in the end I came up with this circuit.

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.

Step 3: Making the Box

The next step is to actually drill the holes for the box.
This is fairly simple, just make sure you measure everything to lay them out neatly and start with a smaller hole and work bigger so as not to crack the plastic.

I didnt have a large enough bit for the switch holes (and if i had it wouldn't have fitted in the drill!), so I needed to drill smaller holes and file out the remainder.

Step 4: Building the Circuit

Basically, all that happens now is that you solder everything together, fit them into the box 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 final thing to remember is that every single one of the grounds needs to be joined together in one big clump! My grounds were all labelled with insulation tape so i knew which they were.

Mostly, it's a doddle, if a little fiddly...

Step 5: Optional Extra Step

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.

Once again, join the grounds with everything else.



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    ***** Just made an improved version and put it on eBay! Search for "3.5mm 5.1 Surround Sound Switch". *****


    Love the instructable, it is just what I need. I have currently finished it but I am getting a high pitch noise when in use, so this is when sound is playing or not. It might be due to interference but I've made sure all wires are not touching. Do you have any idea what could be causing this sound?

    Many thanks!

    2 replies

    Also, the noise disappears when I take one of the speakers away (so unplug one of the speakers completely) So the speakers seem to be interferring with each other.

    Glad you have found this useful!

    If I had to hazard a guess, it might be that the grounds are not connected correctly for that speaker, or as you say, some wires are touching...

    Glad I've helped some people. Incidentally, I no longer have need for my device, so if anybody would like to buy it, pm me and we can arrange something reasonable...

    Hi Guys,
    i'm really happy that i found this site.
    I was looking for various days fpr a solution to switch from 2 5.1 sources ( i have a tv box with a 5.1 adapter and my pc as input sources and my 5.1 speakers as the one output)
    i would have been happier if i would have found this splitter (http://www.hardwareluxx.de/akaspar/reviews/creative_ddts100/connector_s.jpg) , but no chance there!

    so what really confuses me about your switch is that you have 3 on/off switches...why that? i thougt you would need only 1 on/on switch (for source 1 or 2)

    thanks and please excuse my english ;)

    1 reply

    Okay after trying to understand your circuit i think i understood why the 3 switches, when you switch all 3 on ist source 1 and when you switch all 3 off it is source 2 right?

    Hi there,

    I wanted to try using Y splitters first to connect my 2 computers. Would I run the risk of damaging my sound cards or the speakers if I had both systems on at the same time? Would this setup work only if only 1 system was powered at a time? Any help is appreciated. Thanks.

    1 reply

    This was my first attempt, but one system always too prescience, so it didnt work. You may be luckier, but for me it was a no go...

    Hi, thanks so much for this instructable. I have a media center with a small media PC hooked up, and I'm thinking of getting some 5.1 speakers. However, I also have several devices that take the old Phono switch as well as a larger computer for more serious gaming. At first I was going to ask you what modifications I would have to make to have a 3 in 1 out. I was going to do that with this little connector: http://www.amazon.com/Logitech-Console-Adapter-Convert-Single-Pc/dp/B0006U3ACY/

    However now that I see your optional step, am I to believe that this does the same thing?? So it takes 2 real 5.1 inputs and one RCA input that just gets cloned to the other speakers? Or are you saying that it just takes over input 2? I wouldn't ever be using two of these devices at once, however what signal takes precedence? The two computers would almost always be hooked up and on and I'm afraid that would take over the phono input.

    I guess the two questions I have are: Does this step eliminate the need for the gaming adapter? And: If I have two switching inputs that are always on, how do I make sure I can use the phono in as well?

    If this requires 3 inputs do you have any ideas on how to modify this instructable to do that?

    1 reply

    The optional extra step means it takes 2 5.1 and 2 RCA, yes, effectively taking over input two. Regarding precedence, I havent really tested it - one is my xbox and one is my Wii, so these was never any chance they would both be on at the same time (because my monitor turns the sound off from the xbox channel if it's not set to that video channel...
    So, yes, i would say the extra step eliminated the need for the gaming adaptor, in theory. In practice, it's been a little temperamental - it works 100% fine if i just have it going to the front two channels - trying to get it to the rear channels hasn't really worked, although i suspect this may be due to my bad wiring!

    3 inputs would be an extension of this, but you'd need a three way switch, making it significantly more complicated in wiring, and I suspect you'd need a bigger box... (since mine is crammed as it is!)

    Love this instructable, and I'm having a crack at one myself using a single 6PDT switch. Two things to clarify if I may impose:

    Firstly, you say "just bunch all the ground wires together". Do they actually need to go anywhere, or just solder all the ground ends into a single point?

    Second, I see your switches are rated for 3A - is that required, or just what the switches can handle? I've not found a 6PDT switch yet that goes above 1A (most of them are about 500mA), so I didn't want to go ahead and burn the switch out or something!

    Thanks in advance.

    3 replies

    Hi there.

    To answer your questions - nope, the grounds dont need to go anywhere at all - just bunch them up and tape over them for insulation.

    As for the switches, the rating just happens to be what mine were - as far as i'm aware it shouldnt really matter what the rating is - would have thought 500mA would be fine!

    Hope that helps,

    Thanks dude.

    I don't need any special speaker wire do I. I've found some cheap lengths that have polarity marks on them, but I assume that'll just be for a reference to ensure you wire things up properly - in our instance, I'd just need to make sure the "marked" wire connects both (for example) the left channels.

    I ask because my sound card can do polarity checks on the speakers to ensure they're wired properly, but short of miswiring something I can see how I could reverse the polarity on the speaker output.

    Thanks again

    I used the cheapest wire possible and it's still holding up. I suspect better wire may = better sound quality, but to be honest my ears aren't good enough to pick it up!!

    This is a great Instructable! I'm going to build a slightly modified version to switch between my computer speakers and headphones, so there's less wear from plugging in and unplugging. (I have a laptop, but I'm using better external speakers)

    this is really cool, im making something like this right now so i don't have to unplug my speakers to plug in headphones.
    (the front panel audio doesn't work right on my computer)

    What would be involved in making this into an actual mixer, so you could get sound from each simultaneously? That's the thing I'd *really* like to have.

    Why did the PC dominate? Is it just because it was louder? Or is sound transmitted from the monitor dumped because the PC's sucking it to ground or something?

    1 reply

    I wish I could help, but I really don't know! I think it's probably simply a power issue, but I actually don't know, and since it could be fixed for what I wanted, I just didnt look into it further! Sorry!

    First off, I really like this idea, thanks for posting it! I've been trying to find a way to switch audio from my 5.1 Logitech speaker system between my computer and my iPod for when I want to listen to music but don't feel like having my computer on. I'm trying to make something after your model, but since one input is my 2-channel iPod, I don't really need another set of 3x3.5mm jacks. Would I be safe just splitting the wires from each channel of the iPod input itself and running them to each switch? Also, have you stumbled upon a single switch since you first posted this? I'd like to avoid having three separate switches if possible.