Juryrigging 5.1 PC speakers to receiver: possible?

[Xerain]

Over the summer I bought some Logitech X-540 surround sound PC speakers. Long story short, though they're great for playing a 5.1 signal coming from a PC, they don't do much for decoding dolby pro-logic II and/or DTS coming from a game console, even when said console is hooked up to the line in on your sound card through S/PDif or TOS-Link.

(For those of you not familiar with the X-540s, there are 3 male/male stereo miniplug cables that go from you sound card to the 3 jacks on the sub woofer, and then 5 RCA jacks in the sub woofer, one for each speaker. The subwoofer acts as an Amp of sorts, and there is a wired remote with a volume nob, on/off button, and matrixing on/off button that sits on your desk.)

So now I'm looking at buying a Dolby receiver proper, possible a Sony STRDG 510. However I don't want to buy new speakers, as I just got some a few months ago. I'm in an apartment so I won't really be able to benefit from awesome speakers anyhow.

Obviously, you can't just plug the stereo mini plugs designed to go into your sound card into the back of a receiver, which is gearing to have the speakers hooked up through speaker wire... so I'm wondering if I can just chop the mini plugs off of the cables that would normally go to the sound card (or replacements, assuming I want to preserve the originals) and hook the wires up to the back of a receiver?

Also to continue to hear PC sound I'd have an S/PDif going from the S/PDif out on my sound card to one of the S/PDif in jacks on the receiver. I should still be able to hear DVDs playing from my DVD-ROM drive, as well as PC games in 5.1 as I can now, right?

I've heard that this should be possible, but I might have to experiment a bit to make sure the speakers are in phase.

Should there be any problems getting accurate Dolby decoding from a game console to my speakers this way? Also what about a SACD player? I plan to get one of those some day.

I guess it's also worth mentioning that my original plan was to get a sound card that supported Dolby for this purpose and use that as a receiver, but it's my understanding that your best bet for that is a Creative X-fi, that you still need some kind of an add on box, and that it will lag so is not ideal for game consoles. I think I read that here in an older topic, actually. Has there been any developments in this area?

(Also if I get a new sound card I'd rather get one with a C-Media chip rather than a Creative.)

 

[Trombe]

Sorry, no pracitcal way to connect your current speakers to a standard AV receiver. There's the Creative DDTS-100 that can use PC speakers and decode DDL/DTS as well, but it's discontinued and probably goes for more than you'd like to spend on eBay.

As for the sound card's optical out, most can only output stereo via toslink. The common exceptions are the Oxygen HD based cards (Sondigo Inferno, Bluegears b-Enspirer, etc.) and the Auzentech Prelude, and even then it uses CPU cycles to do the encoding.

EDIT: I realize that the Creative Extigy (external sound card) might be good enough for what you want. It'll accept 3x stereo mini-jack conenctions that your speakers use, can decode DDL (not DTS though) through its optical and coaxial ports, 1 of each, and hooks up to your PC via USB. It'll work as standalone too without a PC if you only want to decode DDL for your game consoles. I don't know what sound card you have though, if any, sounds like you have onboard though from the way you're describing this, but if you do, I'm not sure what kind of sound quality hit you'll take from using this. The Extigy is also discontinued, but is far more common and a lot cheaper than the aforementioned DDTS-100, you can expect some $50 + shipping on eBay for it.

 

[Xerain]

Could you please go into more detail why I can't just rip a stereo wire apart and use it as two mono wires? Would there be issues with the amp in the receiver fighting with the amp in the sub woofer?

I don't see why the sub woofer should care wear the signal comes from as long as it is receiving a stereo signal into each of it's stereo jacks.

Also you said there's not piratical way it could work... though it might be just a figure of speech if you know any impractical ways I'd certainly like to hear them.

 

[Mohonri]

The reason you shouldn't plug all the wires from your sub into the receiver is because the receiver's expecting to be driving speakers at a few ohms rather than a line-in at a few thousand ohms. The receiver will be putting out much higher voltages than the subwoofer is expecting (or might be able to handle), and you risk doing some serious damage to it.

Having said that, if you put your receiver on a really, really low volume, it might work. Or if your receiver has analog line-level outputs, you could use those.

In any case, I wouldn't cut off the ends of those cables--you might want them back later. Instead, get some stereo jacks and some wire from your local radio shack or Fry's, and make an adapter.

 

[Xerain]

Actually since the wires are just male/male stereo mini plug I was just going to buy some cheap generic ones and make adapters out of those. Anyhow, the idea was the idea was to save money buy buying the Sony Receiver Best Buy is going to have on sale of black Friday for $99. Would be cheaper than upgrading the Logitech X-540s to Z-550s. The Z-550s have hardware dolby decoding built into the subwoofer/amp as well as TOS-Link in, I think. A full home theater system is a bit over kill in my situation.

If there's a risk of damaging my existing speakers, I'm not going to mess with it. Still it's good to know exactly why it's a risk, so I don't try something like that in the future and wreck some equipment. I'm prone to experimenting like that.