Prologic 5.1 Versus All (Natural) Channel 5.1 Please Explain

[EdwardGein]

Would welcome someones clarification here on what exactly prologic is & its use in relation to 5.1 systems & 5.1 TV Broadcasts and 5.1 DVD's. Specifically, for this post only assume you are playing only a 5.1 DVD or listening to a 5.1 digital TV broadcast not a 2 channel stereo broadcast or DVD/CD.

1. Should DVD's be listened to on the all Natural 5.1 mode on your receiver or should they be listened to in the Pro Logic mode? Which gives better sound? Does the Prologic Mode change the way the sound was originally suppose to be heard in 5.1 all natural in regards to DVDs and TV broadcasts?

2. Same thing on TV. Which sounds better Prologic 5.1 or Natural 5.1 Is the Prologic a distortion of the original sound? I have to admit I heard a TV broadcast in Prologic at someone on this forums system & it sounded great but I'm continuing to listen to TV in the all nastural 5.1 mode because I think Prologic changes the way the 5.1 audio was intended but I could be totally wrong & I'd like to know if I am. Thanks for any answers.

[kexodusc]

With a 5.1 source, Pro Logic shouldn't even be an option. Dolby Digital takes over.
5 channel stereo, and other DSP's that use 5-channels are just a receiver's best guess as to what would sound good coming out of 5 speakers. It isn't "natural" at all.
If you get a 5.1 signal, use Dolby Digital or DTS, or Pro Logic IIx or something newer.

[kexodusc]

On every receiver I've used that can auto-sense the signal, yeah...it takes over. Pro Logic turns 2-channel stereo into a surround sound using information encoded on each of the two stereo channels. Dolby Digital and DTS received 5 dedicated channels not shared with any other.
Pro Logic is okay for TV or old VHS tapes, but for DVD, you shouldn't be using.

Pro Logic II takes these a step further...turns 2-channels into 5, 6 or 7 and sounds much, much more realistic, and better than Pro Logic. It can be used with Dolby Digital and DTS as well to get 6.1 or "7.1" sound. Most decoders also have an EX/ES option on them that adds the 6th and 7th channels as well. I can't hear any benefit to using Pro-Logic II over these if a source is 5.1.

[EdwardGein]

With a 5.1 source, Pro Logic shouldn't even be an option. Dolby Digital takes over.
5 channel stereo, and other DSP's that use 5-channels are just a receiver's best guess as to what would sound good coming out of 5 speakers. It isn't "natural" at all.
If you get a 5.1 signal, use Dolby Digital or DTS, or Pro Logic IIx or something newer.

On the Denons, doesn't 5.1 dolby digital take over automatically?

[N. Abstentia]

Yep, listen to Kex.

I'll just add....Dolby ProLogic is not 5.1 at all. Not even close. Dolby Pro Logic II is 2 channel, with matrixed surround and center...which means it takes the 2 channel signal and like Kex said...takes a guess at what the center and surrounds should do. For regular TV I do like Pro Logic II, it works quite well. It's just the opposite of 'natural' which is not a big deal for TV. But for 2 channel music, I don't want to extra artificial stuff in my 2 channel.

[N. Abstentia]

On the Denons, doesn't 5.1 dolby digital take over automatically?

If you send it a Dolby 5.1 signal then yes it should.

[kexodusc]

Not sure why my reply is up so high...
PL II actually works with 5.1 too, keeps the channels discrete, but matrixes the back channels. I haven't seen anything suggesting it's done any different than the EX option that does the same, but now I wonder...

[EdwardGein]

I'm still a ittle confused what you guys are saying, keeping in mind, I'm only talking about 5.1 DVD's & 5.1 TV broadcasts. Starting with DVD's, the Denons will automatically revert to 5.1 dolby digital unless you put them in DTS. On TV, if its a 5.1 broadcast, to me this means that on the all channel setting it will send the signals to the correct channels & sub as opposed to the Pro Logic which will alter the 5.1 signal. So why should I change from the natural 5.1 setting to the Pro Logic setting for a 5.1 broadcast?

[N. Abstentia]

You shouldn't. 5.1 should be kept on 5.1

Only 2 channel sources such as regular TV or VCR should be used with Pro Logic. Keep 5.1 in 5.1.

Pro Logic is not 5.1

[kexodusc]

Sorry Ed, think I might have confused you. Pro-Logic shouldn't be used for 5.1 sources. Pro-Logic II (the much, much newer technology) can be, and is recommended by some. A paper I've read on it says it will identify 5.1 sources and maintain their discrete channel processing, or turn 2 channel sources into 7.1. I really haven't tried PL II on 5.1 sources other than to see if I could figure out how to engage the processing, so I can't comment on how good it sounds.
But that's Pro-Logic II, and you're concerned with just Pro-Logic for now.

If you're getting a 5.1 signal, Pro-Logic should not even be an option for your receiver. On most models I've seen it's impossible to apply Pro-Logic processing on 5.1 sources.

[EdwardGein]

Thanks actually I have the option of using Pro Logic II Mode & used the term Pro Logic for it.
On the Denons the "5 Channel Stereo" is actually Denons term for all (5) channel (& sub) natural sound. When there is a 5.1 DVD or TV Broadcast, the Denon automatically goes into 5.1 mode. The All Channel Natural Sound is basically just used by me for regular 2 channel CD & non 5.1 broadcasts. Unlike some of the people on this forum, I prefer that to 2 channel (or 2 channel & a sub) mode for regular CDs, as it gives the audio much more depth & I don't really consider the sound being changed because the left signal still goes to the left channels, the right to the right channels & the center is in fact the left & right combined & of course the sub is still the sub.

[kexodusc]

5.1 stereo or whatever you call it isn't bad at all. I use it quite a bit to add more volume in the room. But it does blur some resolution, and can have mixed results. Stereo imaging is actually preserved because as you said, the l/r channels still get fed their info, and only common info is sent to the center channel. It's done in such a way that the left and right remain balanced according to the original sound track.

The problem is the extra dimension it adds wasn't intended or accounted for on stereo soundtracks. So when an engineer makes a decision as to appropriate soundstage "depth" etc, it's done with 2-channels in mind. The corrections he makes don't always work well with 5 channels going. I also find the rear surround cues get can sometimes include sounds that should never come from the rear. But for a best guess, it's pretty darn good.

Try Pro-Logic II's music mode. If I ever use a DSP for music, that's it. It is actually very pleasing on some music sources.

I'd say I use PL II music 5% of the time 5.1 (7.1 in my case) stereo 10% of the time, and just 2-channel stereo 85% of the time.

Maybe that's not right...I also fool around with the DSP's every now and then. I don't 1 or 2. It's just an added level of reverb or whatnot. Sometimes it suits the music.

Most of my critical listening and 1st time listens are done in 2-channel stereo though. That's almost always the best sounding to me.

[topspeed]

EG,

Don't you have your cable box hooked up digitally to your 3801? If so, and when your input selector is set to "Auto," the avr should switch automatically between DD and DPL, or whatever you prefer, depending on the signal it's being sent. For example, almost all of your HD content is in DD, right? It should switch to DD automatically, which is what it sounds like it's doing.

I've got some bad news for you though, your 3801 has DPL, not DPL2. This explains why you prefer listening to 2 channel feeds in 5 channel stereo. I would too! DPL is pretty bad, a fact supported by the fact that they created DPL2. DPL2 does a much, much better job of matrixing 2 channel feeds into a decent facsimile of DD.

[EdwardGein]

Yeah I have everything hooked up by Optic Cable & am more then happy with my TV sound. Can you explain the stuff that you're talking about on DPL versus DPL2 specifically in relation to 2 channel CD's and non 5.1 TV broadcasts. Are you saying that if someone had DPL2 they would prefer listening to CDs & Non 5.1 broadcasts over 2 channels (& a sub) instead of 5 channels & a sub? Thanks for anny clarification.

EG,

Don't you have your cable box hooked up digitally to your 3801? If so, and when your input selector is set to "Auto," the avr should switch automatically between DD and DPL, or whatever you prefer, depending on the signal it's being sent. For example, almost all of your HD content is in DD, right? It should switch to DD automatically, which is what it sounds like it's doing.

I've got some bad news for you though, your 3801 has DPL, not DPL2. This explains why you prefer listening to 2 channel feeds in 5 channel stereo. I would too! DPL is pretty bad, a fact supported by the fact that they created DPL2. DPL2 does a much, much better job of matrixing 2 channel feeds into a decent facsimile of DD.

[topspeed]

Yeah I have everything hooked up by Optic Cable & am more then happy with my TV sound. Can you explain the stuff that you're talking about on DPL versus DPL2 specifically in relation to 2 channel CD's and non 5.1 TV broadcasts. Are you saying that if someone had DPL2 they would prefer listening to CDs & Non 5.1 broadcasts over 2 channels (& a sub) instead of 5 channels & a sub? Thanks for anny clarification.

Not necessarily. A lot of it is personal choice and how you think your rig sounds best. I think that if you like how DD sounds, you'd like your regular tv broadcasts and possibly your cd's in DPL2 a lot more than DPL, especially in "music" mode whereas the mains are used a lot more. I find both DPL2 and DTS Neo6 to be very acceptible when watching anything that isn't already encoded with DD. The surround mix can be pretty convincing! Is it as good as DD or DTS? Of course not, but it's not meant to be.

I'm an old school guy, meaning I only listen to music in two channel, unless:
1) It's premixed mc, such as some SACD's and DVD-A's
2) I'm running around the house and just want back ground music. I use 5.1 stereo for this.

If everything sounds best to you in 5.1 "stereo," then that's what you should use. Your Orbs are different from a conventional rig in that all 5 speakers are the same little ball, instead of mains, cc, and surrounds, which manytimes are different from one another.