[yefchak]

Hi,


I have a DVD of Verdi's Requiem, San Carlo Theatre orchestra which is listed as Dolby 5.1.


The opening DVD "logo" track includes sound on the LFE channel, but once the actual program material starts, there appears to be no LFE signal. I do hear surround and center channels, just no LFE. What's up with this?


If you wonder why it matters, by the way, the Verdi Requiem includes a very famous and very loud bass drum part. They even sell a special bass drum beater just for this piece. Needless to say, the LFE channel would be usefull here.


Package shows the following logos: Image Entertainment. Eagle Vision. DVD Video. Dolby Digital 5.1 Logic? NTSC


--George

 

[scooter_29]

LFE is primarily for effects in movies... not all bass information is directed to the LFE in DVDs... most of the time, full range orchestral information is preserved in the front two channels.


An LFE track for an orchestra would not work terribly well as there is no single source of bass information and there never is a single microphone just capturing bass. In order to achieve an LFE, the mastering engineering would need to extract all LFE information from the main 2 channels and either remove it from the mains or just "double" it to the LFE. In either case, it would represent a very unnatural representation of the orchestra.

 

[yefchak]

Thanks, scooter_29



That makes sense. But given this, why do they market the DVD as 5.1? Two seconds of LFE during the company logo doesn't seem like a valid reason. Meanwhile, apparently there's no bass management option in my system to make use of the sub -- unless, I suppose, I play the DVD in stereo format.


Some day they'll sort this all out, I guess...


--George

 

[scooter_29]

You do get 5.1... just not the "1"...


lets see if I can draw a mic setup that might be used to record an orchestra in 5.1



------------------------


|         &nbsp ;         &nbsp ;         &nbsp ; |

|        SYMPHONY&nb sp;       |

|         &nbsp ;         &nbsp ;         &nbsp ; |

------------------------

                1

              2  3

4         &nbsp ;         &nbsp ;         &nbsp ; 5


Mics 1,2, and 3 are the main pickups. This is a famous recording technique called a Decca Tree that works quite well if you can get your hands on the right microphones. Microphone 1 would be recorded to the center and microphones 2 and 3 to the front left and front right channels respectively.


Mics 4 and 5 are ambiance mics and would be used to pick up the sound of the orchestra hall. They would be sent to the left and right rear channels at a much reduced level than the mains.


If this is properly mixed to a multichannel setup that has identical speakers all the way around, you can recreate a pretty sensational orchestra.


A LFE channel doesn't really do much good here for classical... keep in mind unlike studio recorded music, individual instruments typically don't have their own mic. If they do, it is only as a spot mic and is

 

[lwang]

LFE is useless for pretty much all types of music. Even for synthesized pop music, if they could put drum beats on the LFE, how would they distribute the harmonics of the drum beat? They might be able to slip in those low freq woosh that has no harmonic overtones.


Many DVD-A and SACD proponents wants to make the LFE channel into a 6th full range channel.

 

[yefchak]

OK, all this makes sense. But doesn't this mean that omission of bass management on most amps is REALLY critical? I thought it was just a problem if you want to play DVD-Audios, but apparently it's a problem for this "regular" DVD as well.


My speakers are Maggies, which means I really need my sub in order to get much below 40 Hz.


--George

 

[lwang]

You mean bass management on preamp/proc's 5.1 analog input? Direct 5.1 is a temporary solution since encrypted DVD-A has not been implemented except by Meridian's own proprietary solution.


I have maggies all around also, I basically bypass the processor's bass management and use external dedicated sub with active hgh and low pass crossover for the mains and center channel. Mains cross @ 51hz to its own sub, Center cross @ 155hz to its own sub. The LCR are set to large and no subwoofer is defined, so this way the 2 subs sort of shares LFE.