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Misconceptions in the implementation of the Dolby Digital AC-3 standard
have led to this problem. The Dolby specification (as to be found on
www.dolby.com) specifices the 5.1 norm as a set of five full-range
channels and one Low Frequency Effects (LFE) or "boom" channel
band-limited from 3 to 120 Hz.
The LFE channel is used to reproduce low frequency effects (hence the
name) like exploding airplance, landing of alien spaceships and so on.
All other content (including music) is reproduced by the five main
channels, which are clearly specificed as full range.
Of course we know that most surround implementations for home use do use
the sixth channel not only for the LFE channel as encoded in the AC-3
signal but also for the low range of all five full-range channels
together, will their mid- and high range content is reproduced by five
sattelite speakers.
Rainer
-----Ursprüngliche Nachricht-----
Von: Matthias Grob [mailto:matthias@grob.org]
Gesendet: Freitag, 20. Mai 2005 04:45
An: Loopers-Delight@loopers-delight.com
Betreff: Re:Re: surround looping
>4) the term "sub woofer" has changed it's meaning in recent years,
>the term originally referred to a speaker to handle just the very
>low frequencies that a regular speaker wouldn't produce, hence the
>perception that it just added a bit of depth, and that it didn't
>matter where the sub was placed. The 0.1 in 5.1 is for one tenth of
>the frequency range ....20,000/10 = 2000Hz , which makes it a
>regular "woofer".
I agree that the original idea was to have only non localizable
frequencies on the subwoofer, up to 120 Hz. But 2000Hz cannot be
true, the main part of the voices would come out of the woofer under
the table!
I searched arround and it seems 250Hz is common.
>6) in a gig situation there's no way to get the whole of an audience
>into the sweet spot, and many audience members will be close to
>just one speaker.
> So when mixing a band on a stereo pa I put them in mono anyway :-(
stereo is great for effects and if you put some stuff a little out of
center, you reduce annoing phase cancelations a lot. But I dont mix
any instrument far right or left either.
to have rear speakers is almost impossible because the public behind
will hate them and the public in front will not hear them.
>7) stereo FX (like polyechoes) can sound pretty good, so more
>speakers could really
> add something.
>8) 5.1 is designed for "making the explosions behind you", while
>keeping the main attention on the screen. It's not designed for
>spatial music.
exactly. and most of the 5.1 mixes I heard so far are not spatial
compositions but a band in front and some reverb behind.
In 2002 when I was in California, Gary Hall helped me to create a
surround mix of a piece of mine at Larry O's studio. There the
percussion really jumped happily arround the room!
>When Pink Floyd were using quadrophonics (1967), they had 2 sets of
>pa speakers,
>a main pa, which was stereo(maybe mono, I don't know) and a second
>quadrophonic
>pa (of smaller wattage) for effects. Mostly the sound came from the
>main pa, but the quad was used just to highlight certain instruments
>at various times.
I heard the pigs show (76?) and was not impressed
>I'm all in favour of multi-channel sound, but I don't think there's
>anything special in the 5.1 format.
true. Its quadro with a useless (for music) center speaker and a
subwoofer which is not related to the spacialization...
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