ItsHot
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What is Dolby 5.1 in theaters? 
Dolby 5.1 ?
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jumper
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What is Dolby 5.1 in theaters?
Is this a general question? A quick google search will give you this on speakers and surround sound:
http://www.dolby.com/consumer/understand/playback/dolby-digital-details.html
I am not a real sound tech, I mostly do small set ups. But if clarify your question, there are a lot of guys here who could answer your questions.
Hameedulla-Ekhlas
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"5" speaker channels for the surround sound. ?1? speaker channel for the base speaker. (Sometimes simple answers are better than links. )
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LarryFine
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Congrats on 2K posts!
In what context? Want to call me? PM for my cell.What is Dolby 5.1 in theaters?
ItsHot
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Thanks Charlie! Sorry my question was a little vague! So "5.1" is channels, or number of speakers or both? I'm thinking both. And I know the Dolby side. Like SSD or something is Sony."5" speaker channels for the surround sound. ?1? speaker channel for the base speaker. (Sometimes simple answers are better than links.
ItsHot
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2000 post! Do I get a pair of Kliens ?!!:grin:Congrats on 2K posts!
In what context? Want to call me? PM for my cell.
zbang
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The 5.1 means channels coming out of the sound processor. Usually, there are 3 or 5 speakers behind the screen for the main channels (if the screen is narrow the LC and RC may be dropped), and multiple sets of smaller ones along the side walls for the surround.
ItsHot
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Thank You!
LarryFine
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The number 5 itself specifically refers to five full-range channels (left, center, right, left surround, and right surround). Mono and stereo rear channels up that to 6.x and 7.x.
The .1 refers to the LFE (Low Frequency Effects) channel, so named beccause it suggests 1/10 of the full frequency range (20Hz - 20kHz), even though it's more like the bottom two octaves (20-40Hz and 40-80Hz).
Even more channels have been proposed, such as 10.2, which woulld provide high and low (from the floor) channels to each of the main channels, and stereo LFE channels.
LarryFine
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It's the number of discrete channels. You can have more than one speaker per channel, which is done in most theaters for the surround channels.
That's actually Ray Dolby, who has been a sound engineer for many moons, although he's not the only one developing surround systems.
The first home surround was simply Dolby Surround, with a single surround channel, but they used two speakers, driven 'out of phase' to make thyem harder to localize with the ears.
Like the center channel, the rear channel was 'decoded' from 2-channel stereo, so it could be 'encoded' into any medium with stereo, such as HiFi VHS, stereo OTA and cable TV, etc.
Dolby Digital, on the other hand, uses six discrete channels, which are compressed into a single bitstream, and decoded back into discrete channels by DD-equipped surround processors.
Sony's professional surround system is called SDDS (Sony Dynamic Digital Surround), which is supposed to have more dynamic sound and less compression. Many movies are released in both.Like SSD or something is Sony.
Then there's DTS . . .
electricmanscott
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I have front height channels available on my receiver. I had them connected but there was little noticeable effect.
LarryFine
Master Electrician Electric Contractor Richmond VA
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LarryFine
Master Electrician Electric Contractor Richmond VA
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So I've heard. I have 7.1 in mine. I have a Fosgate FAP-T1+ preamp/processor:
mcclary's electrical
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LarryFine
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Looks like it to me, but that's not my pic, and I never saw the movie.
TwinCitySparky
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Man that's one bad boy processor. Just looked at some specs for it. No amplifier, but I can plug in my security cam.
Very nice!.
LarryFine
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Thanx! Amps I have. A Sunfire Stereo (300w/ch x 2) for the main speakers, and a Sunfire Cinema Grand (200w/ch x 5) for the center, sides, and rears.No amplifier, but I can plug in my security cam.
Very nice!.
Add the stereo powered subs (300w each, built into the main speakers) and that brings the total audio power up to 2200w, and that's a continuous rating.
There's just about nothing this pre/pro doesn't do. The camera input is a neat feature. I was thinking of getting a peep-hole camera for the front door.
If you find yourself in the neighborhood, gimme a call and come watch a movie. (Offer open to any MH member.)
Jumping in late, I was in Corona getting things set up for our annual Renaissance Festival.
To expand a bit on the formats Larry mentioned:
Dolby Stereo, an optical film sound format using the analog tracks (2) on the film. Originally encoded with Dolby A noise reduction (Dolby B, and later C which were common on home audio gear were less aggressive versions of Dolby A) The Dolby A (and it's newest version, Dolby SR [Spectral Recording]) provide both noise reduction and expansion of the dynamic range that can be recorded on the film tracks. Dolby Stereo shot to fame with the 1977 release of Star Wars (ne Star Wars Ep. 4 A New Hope) and really took hold in a very big way (especially for the Cinema Industry which is loathe to adapt to change.) It is a matrix process, the Left and right screen channels are discrete, the Center channel is the SUM (L+R) of the two optical tracks, and the single surround channel is the DIFFERENCE (L-R) of the two tracks, with some level-dependant gain tweaking and a deliberate delay (from roughly 10-100ms) introduced to reduce the audible crosstalk in the auditorium.
For the rest of this post, any time I type "optical (or analog) tracks" or the like I am referring to the above.
Dolby Digital is a discrete 6 channel (5.1) track encoded as data blocks in between the film perforations on the optical soundtrack side of the film. It has robust error correction which on film in good to fair condition is pretty much inaudible, but on really bad condition film it has some odd artifacts. If the track becomes unreadable the processor switches back the the analog tracks.
Sony SDDS (Sony Dynamic Digital Sound, or as us techs call it, System Dumps During Show), is capable of up to eight discrete channels (7.1) which is L, LC, C, RC, R, Surr L, Surr R and Subwoofer. The track data is located on the outboard edges of the film on both edges. It is encoded as a linear series of blocks along the edges. It has terrific sound quality, but it has some serious reliability issues. First off, the tracks are not offset to allow errors caused by damage to be made up for by the opposite edge's track, the tracks are located on the highest-wear area of the film, and the processor itself was overly complicated and prone to crashing. If all that wasn't bad enough, the earliest processors were "total takeover" and handled the processing of the optical track as well, so if the processor crashed, you lost ALL sound as it seemed to always kill the optical tracks as well. (Later units were designed to follow behind a Dolby or other processor.) Sony has abandoned ALL support for all of the SDDS systems.
DTS (Digital Theatre Sound) came unto the scene with the release of "Jurrasic Park." It is actually a very high-tech update of one of the first "sound-with-film" systems, aka Vitaphone. But instead of a lacquer record playing on a turntable mechanically linked to the projector, DTS uses a CD-ROM with proprietary encoding to reproduce 6 channels of sound, and it is sync'd to the projector using timecode printed in the space between the optical tracks and the image portion of the film. It has excellent sound quality and very good reliability, as loss of timecode reading from the film can last up to 4 seconds (the player assumes the projector to be running at the same speed as before timecode was lost) before falling back to the optical tracks. DTS players are always outboard units to a standard processor, with the exception of DTS' ill-fated DTS 6AD which combined DTS with a full optical cinema processor. Great idea, but DTS' Dolby A and SR emulation for the optical tracks was terrible and sounded really bad. The 6AD also had reliability problems. The newest units allow you to load the CD-ROM's for several movies onto a built-in hard drive which meant for double features you didn't have to re-load the right movies' CD-ROMs. The major drawback to DTS is that if the film depot or the theatre who had the print before yours forgot to send the CD-ROMs with the film, you had no DTS playback. Of late the biggest issue though is damaged CD-ROMs as they get banged around in the film cans.
The home video versions of Dolby Digital and DTS are oddly enough superior to the cinema versions, with better decoding and less data compression in most cases.
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