Originally Posted by designit
I’m intrigued to know how Logic 7 was working in the 7550HD’s etc… -- As you (and others with other models) have said, Logic 7 could be applied on top of ‘surround-encoded programs’ (or multi-channel programming)… So did Logic 7’s spec. change?… Are the x600’s using some form of L7-lite?… Or were the 7550’s etc. doing the conversion onboard itself, from multi-channel input, down to 2, then back to 6 or 8ch L7?
Both of these quotes were taken from the same white paper: http://www.3dsi.co.za/HarmanKardon/A...0LOGIC%207.pdf
“Logic 7 decoding is a sophisticated surround sound process that creates a 7.1- or 5.1-channel sound field from two-channel recordings”
“Logic 7 processing changes all of that. Originally developed for high-end processors and available exclusively in A/V receivers from Harman Kardon, the Logic 7 modes use proprietary processing techniques to create discrete 5.1 or 7.1 sound fields from stereo and surround-encoded programs”
Which I assume the meaning is: ‘stereo’ = 2ch / and “surround encoded programs” = quad, 6, 8 etc. channel.
That document was released just a couple generations after Logic 7 first appeared in the HK lineup, and is describing L7 as it pertains to the HK AVRs at that time. Like most present-day models, all HK AVRs were only able to apply Logic 7 to stereo analog / 2.0 PCM digital sources because of DSP limitations, as M Code explained above.
The ability to overlay multichannel streams with L7 was limited to the more powerful, higher end Lexicon processors (Logic 7 originated from the Lexicon brand)
This changed with the AVR435/635. Since then "full process" L7 as M Code described has also been available in the AVR x45s, and the 7550. There have been tweaks between each gen and software updates to improve performance and correct bugs.
This full process version is not just for creating discrete surround back channels for a 7.1/7.2 presentation from 5.1 source material, but is layered over a multichannel digital audio stream applying it's own filters and channel steering. The change can be subtle, or dramatic depending on the source material (purists may not like that L7 is altering the presentation)
"Are the x600’s using some form of L7-lite?"
Yes, as M Code described. This includes all L7 equipped 1/2/3 series or pre AVRx35 4/5/6/7 series HK AVRs to date.
Even the more powerful full-process version found in the recent top-end HK models is dumbed-down compared to real-deal
found in the late Lexicon processors, which have several user adjustments for the L7 processing
"Which I assume the meaning is: ‘stereo’ = 2ch / and “surround encoded programs” = quad, 6, 8 etc. channel."
It is referring to 2 channel matrix-encoded (Dolby Surround / Pro logic)
Here is an actual Lexicon white paper explaining Logic 7 in detail;http://www.lexicon.com/downloads/pro...per%202006.pdf
Long read but has some interesting info