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Surround sound - 2 good + 2 (or more) less good channels?

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Organorak

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostWed Feb 16, 2011 3:36 pm

At the risk of adding extra complexity to something that is already complex, am I right in thinking that if you are playing a DVD, the sound is potentially playable through two (ie stereo) speakers but contains "Dolby" or similar coding that allows an encoder to extract several additional "layers" and thus send a signal through a decoding home cinema style amp to up to six or eight speakers (two front, two rear, one centre and one sub)?

There do exist multichannel PA amps that have four or eight channels (I have one that I'm intending to use for Hauptwerk), and each of these channels would need a single signal from four, six or eight outputs on the audio card. That seems quite logical, sort of similar to connecting active speakers to each of your soundcard outputs but all the amplification being done in one big black box rather than in the speakers. But I don't know if a multichannel amp would be any use for home cinema 5.1 surround sound setup. Of course, when we talk about surround sound in the context of DVDs we mean an arrangement of three speakers up front, two behind and a sub, whereas Hauptwerk has two up front and two rear, and then separately you figure where the sub goes.

Two bits where I'm confused are, firstly if you have Hauptwerk and a home cinema style surround sound, do you have to merge the channels together to pump them into the surround-sound amp, which then splits them up again (e.g. using the optical output of the 1010LT soundcard)? Or does all the decoding happen within the PC and you connect six or eight cables into your home cinema amp? (Put another way, is a home cinema amp approprate for Hauptwerk)? Secondly, is the subwoofer fed a separate channel of low-frequency sounds, or do you feed a stereo sound source (ie two cables) into the sub, which takes off and plays the low frequencies, and spits out the high frequencies so that you plug in your two main speakers into the sub?
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1961TC4ME

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostWed Feb 16, 2011 4:51 pm

Hello Organorak,
Welcome to this discussion, we have somewhat opened a can of worms here but as it goes along I have learned a few things and it looks like others have as well. What I discovered yesterday and Martin pointed out is that we are dealing with 2 entirely different types of surround. A DVD movie because of the way the recording is done requires a surround sound receiver to "decode" and send the audio to the appropriate speakers. HW surround is simply 2 seperate stereo recordings of front and back which is played back through 2 seperate front and back stereo pairs of speakers, a whole different deal and no "decoding" going on. A surround sound receiver for HW is not actually required but to make it easy people are buying and using them for HW surround because the receivers come equipped with multi-channels or multiple stereo pairs out of the box. I have a surround sound receiver for my movie and TV watching but have not tried it on my HW set up because I already had 2 nearly identical amps to use for front and back in my HW setup instead (and the wife and kids would get upset that I took it away for their movie watching). My 2 amp arrangement gives the same results, just a little more complicated with the added equipment. I have not looked at the back of my surround receiver in awhile but as I recall in addition to the 3 connections for the DVD player, it does have separate front, mid and back inputs plus a sub out. So my guess is no, you wouldn't just hook or "merge" it all somehow to one input and then the receiver would dish out the audio appropriately from there, you would instead connect your outs front / back / left / right from your soundcard to the correct ins on the amp. I'm not sure on the optical out issue, I would guess that's only for actual DVD surround not HW, but I could be wrong here. If you have a muti-channel PA that can run more than one stereo pair you could also use that as long as it also has the needed number of inputs from your soundcard. Of course the first thing you need before you can do any of this is the soundcard with multi outs that can also be ran in stereo pairs and assigned in HW as front and back, then correctly connected to either the PA, surround receiver, or to two separate amps which is what I am doing.

Marc
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telemanr

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostWed Feb 16, 2011 4:59 pm

A simple multichannel amp would not decode the extra data stored in a Surround DVD or similar encoded source. You need a proper surround type amp which has decoding circuits built in.

I have a powered sub woofer and powered speakers. I feed HW stereo signal to it and it in turn has two outputs which then feed the left and right speakers. The sub filters out the low frequencies before it sends the signals off to the other speakers.
Rob Enns
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1961TC4ME

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostWed Feb 16, 2011 5:30 pm

Hello Rob,

Yes you are correct on that one, although it would play and you would hear sound, a simple older stereo amp would not work properly (send signals to intended speakers) for a movie on DVD in surround format. If you are wanting to play a surround DVD and hear it as intended you do need the reciever equipped to do so. In the case here I think what is trying to be understood is the difference between HW surround and a movie DVD surround and what equipment and configuration is actually required to properly play back either.

Enjoying 50+ F here in Minnesota today!

Hope your day is going well!

Marc
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pwhodges

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostWed Feb 16, 2011 5:36 pm

A DVD may also be decoded in the DVD player, and fed to discrete amplifier inputs, just to confuse things further.

Paul
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1961TC4ME

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostWed Feb 16, 2011 10:14 pm

And just when I thought I finally had it all figured out! Paul, you have something there.

Let's not forget in all of this that you do also need to own a "surround" sample set.

In both cases it's a combination of having all the peices of the puzzle. With DVD surround you not only need the player, you need the surround receiver. With an HW surround sample set you need the card and the 2 pairs of stereo channels. Without one or the other you ain't going nowhere.

Marc
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Martin_Dümig

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostThu Feb 17, 2011 2:51 am

Hello all,

1961TC4ME wrote:Let's not forget in all of this that you do also need to own a "surround" sample set.


Sonus Paradisi is offering four free surround demo samplesets for download:

- St. Maximin DEMO Sampleset with 10 stops from Positiv

- Smecno DEMO Sampleset with 10 stops from manual and 3 stops from pedal

- Freiberg DEMO Sampleset with 5 stops (encrypted - not running on free Hauptwerk)

- Velesovo DEMO Sampleset with 10 stops on 2 manuals and pedal

This should be enough testing...

Regards - Martin
You can play Bach on every organ.
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1961TC4ME

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Re: Surround sound - 2 good + 2 (or more) less good channels?

PostThu Feb 17, 2011 11:44 am

Hello Martin,

Yes I also saw that Sonus Paradisi is offering demo "surround" sets for download. I downloaded the St. Maximin a few weeks ago fron their site, the file is HUGE! Took about 3 hours just to download it. Unfortunately my smallish 2GB of RAM could not load the full demo set without disabling some of the ranks and various noises this set comes with, so I didn't get much of a chance to see how this set really sounds.

Something else to maybe point out with these surround sample sets is it takes some fairly serious horsepower in terms of memory to load them. My 2GB did not come close as I ran out of memory about half-way through loading the organ.

Marc
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