Shoutbox

A few months ago, I got a new desk for my computer. Before I had the desk, the living room was like this (1337 Paint skills are following): EDIT: Looks like I forgot to put the subwoofer in the images. It doesn't really matter though.



I used to sit at the armchair and the monitor and the TV were in front of me.

Now, I've put a desk (which is now where my computer is) between the R and the RR channels:



As you can see however, the audio channels are now messed up due to this change!
So, I was wondering, is there any way to make the audio channels like this?



Physically switching the cables is not an option, since there are times where I want to sit on the armchair and watch something from the computer on the TV.

I was wondering if it is possible to create a hardware-based solution that where I would be able to select which channels setting I want with a rocker switch or something similar.
The device would have 3 female 3.5mm audio ports which would be connected to the computer via 3 line in cables. The output would be another 3 female 3.5mm audio ports where the cables that are connected to the speakers would be plugged in. Depending on the state of the rocker switch, the device would either "send" the audio as it was received (which means that I'm sitting on the armchair, watching TV), or "send" it to the "correct" speakers (L->R, R->RR, RL->L, RR->RL, C->?? (possibly R and RR?)).
Is that even possible?


Thanks

Offtopic: Here's a picture of the desk:

Bump. Anyone?

I've also drawn two small schematics to show you what I mean by the hardware-based solution.

When the switch/button is into position 1 the setup for watching TV will be used:



When the switch/button is into position 2 the setup for using the computer will be used:



Would that work?

I'm in the same kind of situation (surround speakers positioned properly for TV, but incorrect when using the PC. Wondered the same too, and if you do find an affordable solution I'd like to hear it, but didn't put too much effort into looking for it myself.

The things is, while all my audio from my PC comes through my surround speakers, not much audio from my PC actually is surround sound. None of the music, none of the regular applications, movies are mainly played on the TV screen, high-end games I play on Xbox (TV)... simple games generally don't do surround. So yeah, PC mostly does stereo (x2) where it doesn't that much how speakers are positioned.

Also: If you really want proper surround sound on your PC you also have the center speaker to deal with where by far most of the sound comes from. Watching a movie or playing a game where all of the dialog comes only from the left side gets tiring quickly.

quote:

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Originally posted by Menthix
Wondered the same too, and if you do find an affordable solution I'd like to hear it

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I've made a topic on an electronics forum I found on Google asking for help on that hardware-based solution. Let's see if anyone will reply...

I believe that the hardware solution is the best solution since it works on all OSes and shouldn't have any added latency (where a software-based solution might introduce more latency).

quote:

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Originally posted by Menthix
The things is, while all my audio from my PC comes through my surround speakers, not much audio from my PC actually is surround sound. None of the music, none of the regular applications, movies are mainly played on the TV screen, high-end games I play on Xbox (TV)... simple games generally don't do surround.

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I understand what you're talking about
Sometimes I use SRS Audio Sandbox which will make music play in 5.1. It does a good job at it (at least that's what my ears tell me; not sure about your ears ). Give it a try.

Best bet is probably going to be to just have a box where you route the connections through and you can throw a switch that would throw a set of relays setup to make the connections.

Seem like the best option to me.

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Originally posted by wj
and you can throw a switch that would throw a set of relays setup to make the connections.

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Can you explain that a little more please? I suck at electronics

Like I've said in the other forum, do I have to use a relay? Will a simple 6PDT switch work?

If you can find a decent 6PDT switch, it's very possible it would work. The alternative is to essentially build a 6PDT out of relays. Though I'm pretty sure you don't need to switch the subwoofer, so you would only need a 5PDT.

The following information may make it clearer, it may make it worse. if you don't fully understand I don't blame you, just disregard it. There's no real solution here, just some background on relays.

Most relays have a NC and an NO contact. NC being normally closed and NO being normally open. The common pole is connected to one or the other depending on if power is applied or not. NC and NO are based on when there is no power applied to the relay.

Basically this means when your switch is off (open), there is no power applied to the coil of the relay. When there is no power applied to the coil of the relay the Normally Closed output leg is closed (on), and at the same time the Normally Open output leg is open (off).

When you apply power to your relay coil. the NO leg is closed (on) and the NC leg is OPEN (off).

So in your case you would have the input coming into the common leg, and one set of outputs connected to the NC and one set to the NO.

I would highly suggest NOT combining your center and left/right speaker channels. It's typically not expected when the receiver company builds the receiver and you don't know what will happen when the power is coming/going from different channels.

My solution would be to add an additional center channel speaker and switch between the two instead of trying to mix the audio signals. If you're only using 2 channel audio you may not even notice that you don't have it..

EDIT: To answer your question in the other forum, yes you would need a power source to operate your relays. An old 5V wall charger from a cell phone would probably be your best bet.

6PDT will work if you can get your hands on one, I've never really seen them available to be honest, but they certainly exist - might be worth noting it could well be a cheaper and less confusing (debatable) to use multiple smaller relays, ie 2 x 3PDT or even 3 x DPDT.

You'd have a circuit with a DC battery (voltage depandant on what relays you end up choosing) running through the relays and a switch inline. As for the relays, you simply wire up the two possible inputs and outputs. Here's a sample relay wiring diagram on a single DPDT for just the L and R inputs of your PC:



Note: I'm not entirely sure if this'll work with audio, If there are multiple cores carried through a 3.5mm cable, or if combining channels is the best idea, I use relays all the time for robotics but that's just to redirect power, not actual signals...

EDIT: dammit... Lizard.boy sneaked in there while I was constructing my reply

I know in a standard 3.5mm audio cable there are two channels and a common return. You could think of them as +R, +L, and -both.  I don't know if mixing return paths between the 3 outputs on the motherboard is acceptable or not, so it's quite possible that you would need to factor that into your design.

My first instinct would be to place the device between the receiver and the speakers, instead of the PC and the receiver, and switch the "grounds" at the same time as switching the channels.

quote:

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Originally posted by lizard.boy
If you can find a decent 6PDT switch, it's very possible it would work.

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Define "decent" please

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Originally posted by lizard.boy
Though I'm pretty sure you don't need to switch the subwoofer, so you would only need a 5PDT.

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Do these even exist? A Google Image search for 5PDT shows irrelevant images, but does show some pictures of 6PDT switches when searching for 6PDT.

quote:

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Originally posted by lizard.boy
The following information may make it clearer, it may make it worse. if you don't fully understand I don't blame you, just disregard it. There's no real solution here, just some background on relays.

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Thanks, now relays make more sense

quote:

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Originally posted by lizard.boy
I would highly suggest NOT combining your center and left/right speaker channels. It's typically not expected when the receiver company builds the receiver and you don't know what will happen when the power is coming/going from different channels.

My solution would be to add an additional center channel speaker and switch between the two instead of trying to mix the audio signals. If you're only using 2 channel audio you may not even notice that you don't have it..

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Alright, thanks, I'll keep that in mind. I'll see if I can add speaker on the desk.

quote:

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Originally posted by lizard.boy
EDIT: To answer your question in the other forum, yes you would need a power source to operate your relays. An old 5V wall charger from a cell phone would probably be your best bet.

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Bah!
Having a power source seems weird since I will only be rerouting the signals
Is there any reason to prefer relays over a standard switch?

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Originally posted by stoshrocket
might be worth noting it could well be a cheaper and less confusing (debatable) to use multiple smaller relays, ie 2 x 3PDT or even 3 x DPDT.

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Can you create an example diagram please? I can imagine how the diagram for using a 5PDT/6PDT would be, but I'm not sure about this one

quote:

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Originally posted by lizard.boy
My first instinct would be to place the device between the receiver and the speakers, instead of the PC and the receiver, and switch the "grounds" at the same time as switching the channels.

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Hmmm ... that would be hard because I use two different receivers (one for the L/R channels and another one for the rest of the channels).