What is Pro Logic II and Logic 7 (1 Viewer)

[Jeff Holton]

When I first started getting into home theater 4 years ago... the only thing I had to worry about was Dolby Digital and DTS. Now it seems like there are a million different sound processing options...

My new receiver has Pro Logic II and Logic 7...

With DTS and Dolby Digital, the input source is digital with 6 discrete channels that go to six seperate speakers...

Can anyone help me understand Pro Logic II and Logic 7? I assume Pro Logic II somehow takes an analog signal and converts it to surround sound (like Pro Logic... but better).

And I have no idea about Logic 7...

Can anyone help... or maybe point me to a good websight that I can learn about this stuff.

Thanks

 

[Michael Reuben]

For ProLogic II, try the discussion in the HTF Beginner's FAQ:
http://www.hometheaterforum.com/htfo...764#post552764
Logic7 is, in many respects, a predecessor of ProLogic II; however, it was designed for a system with separate rear and side speakers. It's a proprietary format developed by Lexicon and included in their digital processors. Now that Lexicon is owned by Harmon International, versions of Logic 7 are showing up in some of their other lines. What model receiver do you have?
M.

 

[Jeff Holton]

I just got the HarmanKardon AVR 225, it has Logic 7, but it does not have seperate speaker outputs for rear and side... It sounds like in the HK receivers, this is just a process that uses a matrix to create stereo left & right, matrixed center, and matrixed stero rear left & rear right... just a souped up Pro logic with stero rears... like you said, a predecesor or Pro Logic II.

But I'm not really sure the difference between Logic 7 and Pro Logic II.

Thanks for the response...

 

[Michael Reuben]

But I'm not really sure the difference between Logic 7 and Pro Logic II.

In its full-fledged implementation, Logic7 was designed for a system with seven speakers (front L&R, center, side L&R, rear L&R). More than anything else, that's what distinguishes it from ProLogic II. In addition, Logic7 can be applied to both 2-channel and 5.1 sources (both DD and DTS); with 5.1 sources, it creates a more spacious and enveloping sound field by extracting separate side and rear channels from the 5.1 mix (again, I'm speaking of the full implementation).
It sounds like the version in your receiver has been stripped down to make Logic7 primarily an alternative to ProLogic II. They use different steering algorithms; so your best bet is to experiment and see which one appeals to you more.
M.

 

[Jeff Holton]

Thanks for the info...

So in it's FULL implementation, Logic 7 acts like 7.1 that is available in higher end receivers, except that the extra two channels are matrixed in Logic 7 whereas they are true discrete channles in 7.1?

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And since you seem pretty knowledgable, I'll throw another question your way...

Pro Logic takes a stereo analog signal, and matrixes a center channel signal and a mono rear signal...

Pro Logic II takes the same stereo analog signal and matrixes a center channel signal and a stereo rear signal...

... if the above is true, what difference is there in using Pro Logic II on a regular analog signal, and one that has been "coded" in Pro Logic II. I have a video game that claims to be coded in Pro Logic II. So I assume it is a analog stereo signal, but how can it be different then a "normal" stereo analog signal? And would there ever be a situation where it would be better to use Pro Logic rather then Pro Logic II? My receiver has the option of using Pro Logic II for movies, or Pro Logic II emulator(which mimics regular Pro Logic)

Thanks again for your help... if my above question sounds like a bunch of mumbo jumbo... please disregard.

 

[Michael Reuben]

Quote:

You might not like the way a particular 2-channel track sounds in ProLogic II. Sometimes all that digital processing can have strange side effects; in Logic 7, for example, some DVD interview supplements end up sounding hollow and strange because the speaker's voice gets spread around the room. When something like that happens, you're better off falling back to something simple -- maybe even as simple as basic 2-channel playback. It's purely up to the individual listener. It's nice to have choices, though.
M.

 

[Jeff Holton]

M.

Thanks alot for all the good info...

I have so many questions, and I certainly don't want to bug you all day. Can you recommend a source (on the internet or otherwise) where I can go and hunt for information like this myself?

thanks again

JeffH.

 

[Michael Reuben]

You're welcome!

I'm probably biased, but I think HTF is one of the best resources on the internet for all of these issues. If you haven't already done so, spend some time with the Beginner's FAQ, which has a wealth of information. For other topics, try the forum search feature; the trick is to search for a distinctive term (in this case, "Logic7") so that you can pinpoint the discussions of interest.

M.