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Resolved: the "LFE channel" should never be utilized on SACD/DVD-A.

Discussion in 'Music' started by Rich Malloy, Apr 23, 2003.

  1. Rich Malloy

    Rich Malloy Well-Known Member

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    I'm considering adopting the following Manifesto:

    Every studio producing music SACDs and DVD-As should encode full range signals to all 5 primary channels, and never redirect any bass content away from those 5 primary channels to the so-called "LFE" channel.* Bass management should be entirely a function of the playback system, because only the individual user knows the range and limits of his speakers.

    *Use of the so-called "LFE" channel for "height envelope" and other experimental playback schemes is permitted so long as the use of this channel is entirely optional.

    Or am missing something here?
     
  2. Brian L

    Brian L Well-Known Member

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    Man, I feel your pain, but would this be needed if the various manufacturers got BM right in all formats?

    Being a Pioneer 45A owner, I surely appreciate that BM is often handled poorly. Hardly ANY manufacturer gets it right. My player will NOT send the LFE to the mains in DVD-A when I have it set to no sub (don't know about SACD), and it also will not send bass from the mains to a sub when I have my mains set to small.

    So, without my trusty ICBM, I am screwed with or without bass on the LFE. I think a lot of others are too. As such, I don't know what this buys us. Until BM is done right, everyone is hosed to one extent of another.

    It seems like no one ever had grief with BM when all we had was Pro Logic, but as soon as DD and DTS showed up and we got an LFE channel, stuff started going downhill fast. And then when DVD-A and SACD MC players hit the street, the whole outhouse burned right down.

    Brian
     
  3. Justin Lane

    Justin Lane Well-Known Member

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    Since most DVD-A and SACD are labeled where applicable as 5.1 releases, I think it is safe to assume that a subwoofer will be used in a system (or why would one purchase 5.1 music?). It is important to keep the LFE channel, especially for mass market acceptance, for those who have small satellites or HTIB type systems. LFE distributed to smallish speakers, with no form of bass management available could be a big problem. Of course if the engineer doing the album sends boku amounts of bass to the mains, you are going to run into trouble anyway.

    The ultimate solution is proper Bass management within the Hi-res players, which doesn't look like it is happening anythime soon. I guess another option would be to mandate engineers to send frequencies lower then a certain level to the LFE regardless, but I don't like the possibilities that may hold either. Really it is a sticky issue which has no perfect solution at this point.

    J
     
  4. Kevin C Brown

    Kevin C Brown Well-Known Member

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    I also think a better solution is for the player makers to get the BM issues *correct*, *and* for the studios/producers to agree that the LFE channel should be bandpass limited to < 200 HZ or so. Then it's a heckuva lot more transparent to people with systems already set up for DVD-V (DD/DTS, etc). (Wasn't that the whole idea behind DVD-A in the 1st place anyway?) Make SACD/DVD-A backwards compatible is all I say... [​IMG]
     
  5. LanceJ

    LanceJ Well-Known Member

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    I will admit I don't like using the LFE channel for music either.

    Question: Ever notice all those Panasonic & Sony hi-res HTiB's with tiny satellites? What are THEY using for bass management???

    LJ
     
  6. Wayne Bundrick

    Wayne Bundrick Well-Known Member

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    The manufacturers and the recording labels should stand side by side so that we can deliver a pimp daddy bitch slap to both of them, "Three Stooges" style. Because each of them have surely f***ed things up from opposite directions.

    I don't agree with the idea of "DVD-A discs are labeled 5.1 so they assume you really have five speakers plus a subwoofer." I also don't agree that LFE should never be used. That's treating the symptom and not the disease.

    I seem to recall that before the DVD-A specification was completed, someone had the presence of mind to include a table of "rosetta stone" data on the disc which would give control on a song-by-song basis over exactly how these six channels of audio are to be downmixed by the player in the event that the listener does not have five speakers plus a subwoofer. I want to know why neither the manufacturers nor the recording labels are using it.

    A pimp daddy bitch slap, I tell you. Three Stooges style.
     
  7. Lewis Besze

    Lewis Besze Well-Known Member

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    If a complete BM is adopted in the players universaly,then it won't matter if the LFE channel is utilized.
    The new Denon is very promising,that manufacturers start to "see the light".Sound mixers for music,just like the movie counterpart, are endowed with an "artistic licence",they all have different ideas,as how music should be mixed.
     
  8. Brian Perry

    Brian Perry Well-Known Member

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    If memory serves, the reason the .1 (or LFE) channel was added in the first place was because there was the potential that certain bass-heavy movies would oversaturate the capabilities of the 5 primary Dolby Digital channels and that an extra 6dB or so might be necessary. Otherwise, there would really be no need for the .1, as your pre/pro would simply direct bass from the main 5 channels as necessary.

    I don't think DVD-A or SACD has this limitation, so I agree with Rich in that the .1 isn't necessary. That's not to say in some systems a subwoofer isn't required--just that the subwoofer can get all the info from the 5 main channels. (Of course, this is complicated by the lack of a digital interface and that BM needs to be handled by the player.)
     
  9. Leo

    Leo Well-Known Member

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    If we were sold a product that stated it was to handle bass management correctly, and in fact doesn't, wouldn't it be considered a defect that should be corrected as a warranty issue?

    Just my .02 cents
     
  10. Michael St. Clair

    Michael St. Clair Well-Known Member

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    It seems that some engineers just dump some of the bass into the .1 channel so that people without bass management still get some bass. I think a few engineers have actually confirmed this. Of course, this means that people with bass management and/or full-range speakers all around may get too much bass.

     
  11. Jeff Ulmer

    Jeff Ulmer Well-Known Member

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    LFE should never be used for music. They don't call it Low Frequency Effects channel for nothing. All speakers should be sent full range audio. If a component doesn't have the ability to manage that properly, it is defective.

    I am also opposed to mixing in the center channel. For music, 4.0 is the way to go, even if it doesn't fill up all the speakers (which it will, at last to 4.1 if bass managed properly).

    The workaround for most of these systems is simply to set your speakers to large, and adjust the crossover point properly.
     
  12. Cees Alons

    Cees Alons Moderator
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    I totally disagree.

    Sending the bass to a specific separate channel was done long before we even had 5.1 (or Pro-Logic, or so). Producing bass at several places in a relatively small room is like asking for trouble.

    Also, the idea of splitting the frequency range of a channel is a very good idea. There is absolutely nothing wrong with having the bass come from another place, as long as it is produced in that (relatively) small room and the bass frequencies are chosen low enough.

    The alternative is multi-driver speakers with cross-overs, which is only a second best solution (cross-over filters have big phase shifts - I wouldn't even call it a solution at all). Bi-amping would be the only proper way to do it, but as said, most of the bass waves of all channels are more or less in phase, and producing them at more than one place is the source of many sound problems.


    Note: the original proposition in this thread is a good idea - but I don't think a studio ever sends (records) any non-LFE bass to the LFE-channel. The BM does that.

    Cees
     
  13. Rich Malloy

    Rich Malloy Well-Known Member

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    Cees, I think perhaps you're missing the point. I agree that reproducing bass at several points in the room is bad. I agree that splitting the frequency range of a channel can (more accurately "may") be a good idea.

    But I'm arguing that I should retain control of how I allocate the bass among my speakers. This control should not be assumed by the mixing engineer who does not know my room, does not know my equipment, and does not know my listening preferences. This "one size fits all" approach will clearly be inapt for many systems.

    Moreover, there's no small contingent of music-listeners who prefer not to use a sub altogether. Even those whose systems cannot reproduce the full frequency range of the cannon blasts in the 1812 Overture, or the lowest pedals of a pipe organ, may nonetheless prefer the more seamless integration of their main speakers sans sub. You and I may disagree with them, but it should be their choice. And you and I should be free to assign to the sub channel whatever bass you and I choose to, at the frequency point most apt for our systems. I'm simply saying this should not be the choice of the mixing engineer.
     
  14. Cees Alons

    Cees Alons Moderator
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    Rich,

    My first sentence was aimed at Jeff Ulmer's statement.

    My two last sentences served to agree with you [​IMG]. Except that I don't think any mixing engineer directs bass to another channel than where it should be. However, IF he does, I apparently agreed with your thesis.


    Cees
     
  15. LanceJ

    LanceJ Well-Known Member

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    Thanks Michael. Too bad manufacturers can't include such a simple system in their standalone players. For many people the "small" setting for all their satellites would work fine. Then just a simple b.m. "on/off" button on the front panel would be needed.

    Sort of primitve, but better than blowing up your expensive B&W or Dynaudio sats.

    LJ
     
  16. Javier_Huerta

    Javier_Huerta Well-Known Member

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    Hold on a second... if I / anyone else have a 5.1 / 5.0 setup, which is correctly calibrated, I'd assume the following.

    1) The 5.1 setup will be able to achieve 20 Hz or lower frequencies, while the 5.0 won't (just because two bass sources usually cancel each other at certain frequencies).

    2) Both will practically sound the same over, say, 40 Hz and up.

    The only way I see both requisites could not be mutually exclusive would be by using 5.0 channels and letting the user handle the bass management part. As I remember it, I think the Dolby web site used to say the LFE was used to *add* an extra amount of power to bass, and that it shouldn't be mixed to the mains to avoid overpowering them. So, in effect, the LFE would only be appreciated by those with a subwoofer.

    Bottom line is - unless it happens to be the "1812 Overture" cannons firing, I don't see any use for an LFE on music... IMHO.
     
  17. Wayne Bundrick

    Wayne Bundrick Well-Known Member

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  18. Brian Perry

    Brian Perry Well-Known Member

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  19. Philip Hamm

    Philip Hamm Well-Known Member

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    I was going to mention the "1812 Overture" cannons as a good candidate for LFE in music as well. Other than that, I agree, the LFE channel should not be used for music, it really isn't needed.
     
  20. Rich Malloy

    Rich Malloy Well-Known Member

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