5.1 and stereo

**mbaratta** · 05-23-2004, 11:30 PM

If someone has a dvd HU or carputer with optical 5.1 output and wants to add a 5.1 DD processor, how do you keep stereo music playing normally and just the dvd's being decoded into 5.1.

Obviously the stereo rcas would go to your x-over, or amp etc. and the 5.1 optical output to the 5.1 processor, but what about after that.
Does the output of the 5.1 go into the amp also?

Can you set up the pc so DVD's only play out of the optical output? And everything else comes out of the rcas?

I'm just very confused on how to do both. or does fm radio sound good in 5.1 and eliminate the need for the x-over?

then there's nothing to worry about.

Any help would be appreciated. Links, or how some of you guys have done it.

**Teenkertoy** · 05-23-2004, 11:57 PM

I have a 5.1 setup in my living room right now where just about every source I have is split into 5.1 including: DVD, radio, tv, cd player, ps2. Because my receiver supprts it, I can take a 5.1 source and downmix it to stereo, or upmix a stereo source to 5.1. I prefer using 5.1 for most things, but for CDs I always use stereo because CDs are engineered to be heard on a "stereo" system.

That said, in a car I would recommend using stereo for the radio and CD player because radio broadcasters use processing to enhance the 2channel audio before it gets to your car (I work in radio). Plus you will get to use your crossovers and subs...etc... I would use 5.1 for DVD playback because that is the way it is intended to be heard. This is only my oppinion though.

For hookups, ideally I would have a HU feed a 5.1 decoder that is capable of passing both 5.1 and stereo signals to the outputs (rca I assume). Then use your HU to select 5.1 or stereo output.

I think that makes sense, let me know if that helps.

~Teenkertoy

**ppgt94** · 05-24-2004, 12:08 AM

I use a Turtlebeach Santa Cruz sound card. If the source isn't encoded for 5.1 surround I have it set to just "fake" it. Basically it just plays the stereo channels on front and rear speakers. I bypassed (more like got rid of) the HU, though.

**mbaratta** · 05-24-2004, 12:49 AM

ppgt94 and teenkertoy:
So basically, fm radio doesn't sound good in 5.1...ok

teenkertoy:

so if you use both, the crossover for stereo sources, and the 5.1 proc for dvd, how do you run them both into an amp?
do you just use a splitter/joiner?

or am I missing something.

Its my understanding, that for 5.1 sources, the proc performs the same functions as the x-over. So after the proc you will have FL, FR, C, RR, RL and sub outputs. Obviously the sub output is low frequency (.1) and that goes to the sub amp...and to the sub.

I know amps have stereo inputs, but what about inputs for the (4) FL, FR, RR, RL outputs?

Thanks to you guys I kinda understand the why, just confused on the how.
I wonder if maybe alpine, or some other manufacturer will have a sample system diagram on how a 5.1 proc fits in a system so I can visualize it.

maybe I should just get the turtle beach sound card...sounds easy

**antimatter** · 05-24-2004, 12:57 AM

Okay check it...

When you purchase a DSP (digital surround processor) such as the Panasonic CY-AC300EX it does all of the processeing. So your analog line and digital line (S/PDIF [toslink or coax]) would all go from whatever (carputer/headunit/dvdplayer) and split it up into 6 analog channels that would then get fed into the amp. Usually amps have crossovers but if there are external crossovers they go inbetween the amp and the speakers.

The DSP calls all of the shots...meaning it decides how the sound gets interprited and which channels it goes to.

In my setup (using the panasonic mentioned above) it interprits MP3's as Linear PCM which is basically stereo. And DVDs as Dolby Digital. when everything goes to the DSP first there is no need to worry about having stereo and digital sources. They integrate well

Look in the Car Audio Forum. I did a write up on how to get 5.1 the right way with Dolby Digital DTS and Prologic using the carputer as the source (no HU)

**mbaratta** · 05-24-2004, 01:04 AM

antimatter:

I partially read that other thread, and I think I asked a question too.

It helped, but my main, dumb, simple question I think has been answered in this thread:

When playing a 2 channel source does it have to be output seperately to remain 2 channel, thus having 2 inputs in the audio section of the setup?

but ppgt94 answered that with the santa cruz, and probably others, you just tell it not to process the signal. and "fake it" in four channels.

So instead of getting an outboard proc like the panny, I can just use a sound card.

thanks antimatter

**antimatter** · 05-24-2004, 01:29 PM

Yea this is true...but why do you want 5.1? Are you watching DVD's with DTS or Dolby Digital or DivX movies encoded with Dolby Digital?

If you decide to go the sound card method then watch out for the following things.

1. Introduced noise as sound cards werent meant for such a harsh environment as a car (thats why i ran everything didital)
2. High utilization of USB bandwidh (if you go with a USB sound card watch the USB bandwidth with addition of other USB devices especially ones that consume a lot of USB bandwidth like IDE-USB bridge)
3. Before you get in to deep realize that you will not achieve DTS decoding with this setup.
4. You may have problems controlling the sound properly with the frontends that are available

There are caviats with all setups and these are the ones for using a USB sound card

good luck

**falconey** · 05-24-2004, 02:02 PM

Originally Posted by Teenkertoy

I prefer using 5.1 for most things, but for CDs I always use stereo because CDs are engineered to be heard on a "stereo" system.

That said, in a car I would recommend using stereo for the radio and CD player because radio broadcasters use processing to enhance the 2channel audio before it gets to your car (I work in radio). Plus you will get to use your crossovers and subs...etc...
~Teenkertoy

This is exactly why I don't understand the added cost of doing the 5.1 in the car. It's like how many movies are you going to watch in your car. You wouldn't ever have time to watch movies and get the full enjoyment of the surround sound and like you mentioned cds aren't designed for surround sound. I'm like if it's not a show car or if you aren't taking two hour trips every other week, is it really worth it. Then again someone may look at having a computer in the car the same way as I look at the surround sound thing. I'm not flaming anyone I just don't understand the added cost. It's not like listening to the audio from a movie will sound terrible in stereo.

**antimatter** · 05-24-2004, 02:07 PM

@falcony

Thanks for that pointless rant.

**Teenkertoy** · 05-24-2004, 02:26 PM

Originally Posted by falconey

This is exactly why I don't understand the added cost of doing the 5.1 in the car. It's like how many movies are you going to watch in your car. You wouldn't ever have time to watch movies and get the full enjoyment of the surround sound and like you mentioned cds aren't designed for surround sound. I'm like if it's not a show car or if you aren't taking two hour trips every other week, is it really worth it. Then again someone may look at having a computer in the car the same way as I look at the surround sound thing. I'm not flaming anyone I just don't understand the added cost. It's not like listening to the audio from a movie will sound terrible in stereo.

Falconey has a point. I never plan to use 5.1 in my car because it simply won't sound right. The center channel speaker will most likely be about the size of a small cell phone and won't reproduce a soundtrack very well. Unless a car comes from the factory with a 5.1 system already installed, it just doesn't make sense to me...

...pointless rave or not, I agree...

~Teenkertoy