LPF on LFE at 80hz, where does 80-120 go???? - Page 2 - AVS Forum
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post #31 of 36 Old 09-15-2010, 09:45 AM
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Quote:
Originally Posted by jmilt13 View Post

Ok, maybe I meant more along the lines of;

If the LFE is a limted channel, which by its very purpose it is, why hasn't there been a standard developed as to what audio data it will contain?

Seems to me things get directional above 80hz and it should be a digital track 0.1 standard....(screw anyone with bose style mains) Could movie theater setups have anything to do with this standard not being developed?

... or why isn't the LPF a proper "inverse crossover", redirecting to the mains, so nothing is disregarded.

You have very valid points. And more than likely, the theater set-ups drove the standard more than a completely common-sense logical approach (all designs are compromised by real-world implementation factors, including politics and other non-technical reasons).

Indeed, it seems weird to define the frequency response characteristics of a "Low Frequency Effect" channel with any content that isn't truly low frequency/non-directional, but it was probably a compromise in terms of where to put the content associated with loud explosions without impacting the SNR of the channels carrying other content. i.e. there may have been concern that if the 80-120 Hz content from explosions is carried in the LCR instead of the LFE, it might mean the headroom needed for those explosions would lower the overall signal level of the rest of the LCR content to an unacceptable range. I don't think that truly is a concern, but maybe the first generation(s) of systems using an LFE channel were sketchier than today's technology. (I have no idea - just tossing the idea out there.)

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post #32 of 36 Old 09-15-2010, 10:32 AM
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Quote:
Originally Posted by shinksma View Post

You have very valid points. And more than likely, the theater set-ups drove the standard more than a completely common-sense logical approach (all designs are compromised by real-world implementation factors, including politics and other non-technical reasons).

Indeed, it seems weird to define the frequency response characteristics of a "Low Frequency Effect" channel with any content that isn't truly low frequency/non-directional, but it was probably a compromise in terms of where to put the content associated with loud explosions without impacting the SNR of the channels carrying other content. i.e. there may have been concern that if the 80-120 Hz content from explosions is carried in the LCR instead of the LFE, it might mean the headroom needed for those explosions would lower the overall signal level of the rest of the LCR content to an unacceptable range. I don't think that truly is a concern, but maybe the first generation(s) of systems using an LFE channel were sketchier than today's technology. (I have no idea - just tossing the idea out there.)

shinksma

The LFE channel is boosted by 10 dB on playback. This allows the LFE channel to be recorded at the same level as all the other channels, but still be "louder" in the final output. The LFE is supposed to be duplicated in the main channels, so even if a subwoofer is not used, the information in the LFE channel is not lost. However, it would not receive the 10 dB boost if it's in the main channels. Only if it's in the LFE channel. Also, that "guideline" is not always followed by recording engineers.

In addition to the LPF of LFE, most modern receivers and pre/pro's have an LFE level setting. This is to keep or reduce the LFE boost. In general, the boost should always be kept, which would be the "0" setting of the LFE Level.

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post #33 of 36 Old 09-18-2010, 08:40 AM
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hi guys, new to this site and i have a question calibrating my BIC f12. I ran Audyssey and my speaker level settings are:

front: 60 hz
center: 70 hz
surround: 60 hz
LPF of LFE: 80 hz

My question is what do I set my subwoofer to? On the back of my subwoofer I currently have the crossover frequency to 80 hz. If anybody could help me out, I'd greatly appreciate it. Sorry for the newbie question. I just got my surround sound set up last weekend and really don't have any prior experience. Thanks in advance!
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post #34 of 36 Old 09-18-2010, 08:53 AM
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Quote:
Originally Posted by kyle6286 View Post

hi guys, new to this site and i have a question calibrating my BIC f12. I ran Audyssey and my speaker level settings are:

front: 60 hz
center: 70 hz
surround: 60 hz
LPF of LFE: 80 hz

My question is what do I set my subwoofer to? On the back of my subwoofer I currently have the crossover frequency to 80 hz. If anybody could help me out, I'd greatly appreciate it. Sorry for the newbie question. I just got my surround sound set up last weekend and really don't have any prior experience. Thanks in advance!

Your questions deserve a new thread.

Before answering, I'll suggest you read the Audyssey Setup Guide in the Official Audyssey Thread:
http://www.avsforum.com/avs-vb/showthread.php?t=795421

The answers to your questions, (and much more) are there.

Craig

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post #35 of 36 Old 09-18-2010, 09:00 AM
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ok, i'll look that over. thanks for the help
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post #36 of 36 Old 08-17-2012, 12:06 AM
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Guys, I need to know something:

What if my AVR (Denon 2808) DOES NOT have a LPF of LFE setting? What will happen with the LFE content from 80Hz and up? Will I lose it or does it mean that when a AVR does not have the LPF of LFE option it sends all the LFE signal by default to the subwoofer without a upper filter?
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