Home Theater Fans: Does 5.1 Mean All Channels Are Integrated?

[kelticwizard]

Having a discussion on the following thread:
passive filter for sub


Moi has a Sony DVP-S735D DVD Player, which is apparently both a DVD player and A/V preamp.

It has 5.1 channels, Mpeg and DTS decoder, whatever that means.

http://www.amazon.co.uk/exec/obidos/...362704-3990861

http://www.amazon.co.uk/exec/obidos/...362704-3990861

He has the Audio outputs from this to a variety of amps. His question: Is the subwoofer fully integrated with the satellites and center channel crossover-wise?

I would think that the 5.1 system would mean that there is an internal crossover which cuts the subwoofer in at the same frequency that the satellites are cut out, therefore making any external crossover unnecessary.

Is this the case? Is any unit that carries the "5.1" label set up so that you can just hook up the Audio outputs to appropriate amplifiers and forget about crossovers? I am looking for confirmation here.

Thanks.

[mrfeedback]

What is the LFE channel? might help you.
According to Dolby, the 0.1 channel channel is named LFE (low frequency effects) and runs 120Hz and down.
Dolby Technical Overview

Hope this helps,
Eric.

[purplepeople]

keltic,

Quick answer: Yes, the channels are already properly filtered before the outputs.

Caveat: Only for units with 5.1-ch analog outputs. Anything with only 2-ch output has downmixed AC3 into matrix for ProLogic decoding.

For Sony, the XO for the sub is 120Hz.

How? I have a Sony DVP-NC650V 5-disc DVD/CD/SACD changer. It has 5.1 analog outputs and all I need are 6 channels of amplification.

:)ensen.

PS: I'll post this in Moi's thread too.

[Ken L]

Not looking at the manual or owning one,it is hard to say specifically with any certainty because there are variations in the chips and how units are setup.

However, my Nakamichi did cut in the LFE only when being fed a 5.1 single and when being fed a stereo signal you could not select LFE

HTH

Later

Ken L

[purplepeople]

I believe the various 5.1 standards specify the XO frequencies prior to mastering and a 2.0 mix is offered on most DVD software for those without the AC3 or DTS decoders.

Although not strictly needed because of the secondary software mix, my DVP-NC650V can also downmix the 5.1 into 4.1, 4.0, 2.1 and 2.0 if I set up the internal "speaker" menus. I'm guessing this is done with DSP. I find this feature handy as I'm currently running 4.0 into a 4-buss mixer and XO a sub post fader off the L/R mains. As you can see I will need a 6-channel pre to do this properly one day.

It also has a normal L/R output for use with a ProLogic receiver and that would be when one selects the 2.0 mix in the software.

I can't imagine that a player with 5.1 output wouldn't also downmix since most of them would have internal menus for "speaker" set-up.

:)ensen.

[tiroth]

Bass management is generally implementation-specific. My processor has "large" and "small" settings for each set of speakers (front, center, rear) and routes bass differently depending on the selection. It does provide a sub output in all modes. (Technics SH AC-300)

Despite this you will still need some post filter if you have large main speakers. If your mains go down under 40Hz and the sub is crossed at 120Hz, you can get some serious boom. I think this will require playing with filters to determine what sounds best. There will probably be a tradeoff between cinema impact and musical fidelity...which is why I'm considering some selectable filters for my system. Anyone done this? How was the result?

[purplepeople]

On my DVP, I can set Large/Small/None for any of the 5 satellites and Yes/No for the sub. If I select No Sub, then bass automatically gets diverted to the mains if the L/R mains are set to Large. I do not know what happens if I select No Sub and Small Mains.

I'm guessing that if I select Yes Sub, then normal AC3 takes over and <120Hz gets sent to the sub and >120Hz to the mains - but I am only guessing. Anybody know what AC3 and DTS specify in this case?

As for music, the manual suggest using the 2-ch output for best results. I don't normally use the sub for music, but on the weekend, I loaned the system out as a PA for the office picnic and just fed the full-range signal into the sub which, of course, was forced into using it's onboard LPF.

:)ensen.