can somebody please decipher the complexities of DTS 5.1 for me?

[symbiosis]

Hi

I'm really new to this home cinema stuff and need some advice re sound cards/amps etc please. I use this primarily to play back DVD's with 5.1 sound tracks.

I have a fairly old Pc (a P3) that I'm using at the mo for my home entertainment Pc and would like to have 5.1 sound (as I already have the speakers in place from an amp that blew a while back).

My questions are:

I can get hold of an audigy 2 card and have an amp that has pro logic on it. If I use these two together - will that give me 5.1 sound? Bit confused with the difference in pro logic and 5.1

if not, do I then need a 5.1 decoder AND amp or does the card do the decoding?

I need the amp to have multiple inputs (as well as inputs from the pc) so it would need to have a regular stereo input as well as the 5.1 - do most of them have that?

Does anyone know how to wire up the audigy to an decoder/amp

Thanks

 

[piff470]

I can get hold of an audigy 2 card and have an amp that has pro logic on it. If I use these two together - will that give me 5.1 sound? Bit confused with the difference in pro logic and 5.1
It will depend on which specific card you're referring to. The card will either output audio as a digital signal through a SPDIF socket, or (more likely) as analogue audio through 3.5mm jacks.

If you output digitally through SPDIF, you'll need the amp to do the decoding. If you output analogue through 3.5mm jacks, you'll need a software codec (e.g. ac3filter) to decode. The amp will then just amplify the decoded signal.

Pro-logic audio carrys an extra audio channel 'hidden' in the normal stereo channels. A decoder (either on your amp or a software codec) translates the hidden track into a centre speaker track and a mono surround track.

5.1 audio is more sophisticated and has 5 separate audio tracks. The ".1" is the subwoofer track, but if you don't have a subwoofer this track is wrapped up into the other channels.

if not, do I then need a 5.1 decoder AND amp or does the card do the decoding?
You either need:
1. a software decoder and an amp with 5.1 channel inputs, or
2. you need a sound card with a digital output and an amp with a digital input.

I need the amp to have multiple inputs (as well as inputs from the pc) so it would need to have a regular stereo input as well as the 5.1 - do most of them have that?
Most amps would have this, but make sure you check for the specific model you're buying.

Does anyone know how to wire up the audigy to an decoder/amp
For a digital output, you need a single cable from soundcard to amp. It will either be coaxial or optical, depending on the sound card.
For analogue connections, you'll need 3 cables, each a with a 3.5mm jack on one end and phono plugs on the other.

 

[symbiosis]

Thanks for the reply - very informative!!

Just one more thing, the Soundblaster Audigy2 card has got digital out (although I'm not sure what cable I'm supposed to use as it looks like the same port as all the other outputs)

If I use the digital out, would I need an amp with a decoder or could I use a software decoder with just an amp?

I'm running an old P3 PC - would that handle the decoding?

Oh, and I guess that means that my old pro logic amp is useless to me if I want 5.1?

Cheers

 

[symbiosis]

Ok, from what I have read, I can either output via my digital out on the soundcard from the 3.5mm mono jack to a Coax or to a TosLink optical cable - is one better than the other in terms of quality?

I've read that I have to select the digital output on my card's software to do this but will I still be able to send stereo signals to my amp from the digital out as well as 5.1?

Cheers

 

[Stephen Neal]

1. If your amp is ProLogic only - does it have a coax or toslink optical input for digital audio? My understanding was that ProLogic amps were pre-cursors to digital audio and instead decoded Dolby Surround information encoded in Dolby Stereo analogue soundtracks (from VHS HiFi tapes and NICAM stereo broadcasts)

2. If your amp DOES have a coax or Toslink input then there should be no quality difference between coax and Toslink inputs in an ideal world - though jitter can be an issue so one may sound a bit better than the other. (Toslink has the advantage that it doesn't suffer from interference - one coax connection I had got zapped when my central heating went on and off - but that was using cheap cabling so the shielding may not have been that good)

In this case your amp is doing the Dolby Digital and DTS decoding, but stereo stuff will also be passed as PCM 2.0.

3. If your amp DOESN'T have coax or toslink digital inputs but does have inputs for rear surround speaker feeds you may be able to take 4 or 5 feeds from your Audigy II (Front Left and Front Right on one stereo pair and Rear Left and Rear Right on another stereo pair, and possibly also a centre feed on a third output connector)

This would allow your PC to do the decoding of the Dolby Digital or DTS audio which it would then output as multi-speaker analogue to your amp.