Nathan Eddy

Can Dolby Digital 5.1 be used at live concerts?

I've heard Floyd's quadraphonic surround sound during the '94 tour, but can DD 5.1 be used in the same way? Given that it was developed for home theaters (I assume), does this question even make sense?

I read an interesting discussion on this topic recently, and some participants claimed that groups are actually employing DD 5.1 at live shows. But I don't see how this makes sense given that the format is designed to accommodate small satellite speaker systems that divert low frequencies to the LFE channel. Why would a concert venue need to use bass management? Why would it need a LFE channel at all?

I realize that more affluent home theater enthusiasts can substitute the satellite-subwoofer combo with five full-range speakers, and perhaps something like this can be done for concerts. However, the concept of applying home theater technology to a large arena seems bizarre to me.

Does anyone have more info on this?

Tim Hoover

There wouldn't be a need to use an encoding scheme like DD at all. Given the creativity of the live sound engineer, I imagine you could use just about any speaker array you wanted...

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Nathan Eddy

Tim, so you're saying that Dolby Digital encoding is unnecessary for live surround, that a sound engineer could produce live surround without it? Or is DD actually inappropriate and/or unusable for live shows?

I was under the impression that the 5.1 format was a way to get surround sound into your home in a small, easy-to-use system, and that this kind of setup is inappropriate for applications involving 10's of 1000's of people. If someone wanted to use it for concerts, could they?

Vince Maskeeper

There are several live surround boards, the Beastie Boys did a large scale arena surround tour in the mid 90's. Just like "cd" audio is not involved in the concernt environment, DD5.1 is not involved.

Do need for an encoding scheme at all (especially a lossy scheme like DD)-- live instrumentations can be routed to "surround" placed speakers by the mix engineer.

Vince

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Aaron Silverman

In a live situation, the sound mix would just be routed to whatever speakers (including LFE) that the sound engineer wanted. DD is a compression and encoding scheme for squeezing 6 channels of sound into a single data stream (i.e., one that travels from your DVD player to your decoder via a single cable).

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Nathan Eddy

Well, it seems a consensus is developing. Thanks for the help. In the discussion I mentioned above, a couple guys with a lot of technical jargon have kind of "ganged up" on me, and used my audio ignorance to make their opinions sound like facts. I didn't think it made sense to use DD 5.1 in concert, but since I don't have the technical jargon down, I couldn't effectively argue against them. Thanks again.

Tim Hoover

LOL....Nathan, I think you're getting the hang of it just fine. DD is an encoding scheme used for the storage and reproduction of multichannel sounds. Since the music would be played live, there would be no need to encode it, as the sound engineer could just bounce the sound to whichever speaker he wanted to in real time.

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Michael Reuben

A few more points:


DD's first application was in movie theaters. It was developed for a wide variety of uses, including theaters, home theaters and HDTV.


The opposite is true: DD was designed to provide five full-range channels (as opposed to the old Dolby Surround, which had frequency limitations in the rear channels). The fact that many HT systems use speakers that are less than full-range, thus require receivers with crossover to divert low frequencies to the subwoofer, results from equipment design, not the DD format.

Also, do not confuse the LFE channel (the ".1" in "5.1") with bass frequencies in general. There is nothing in the LFE channel that could not be included in any of the five other channels, and indeed there have been some mixes that don't use the LFE channel at all. It's there to give sound designers the option of including an extra "boost" to the low frequencies if they so choose.

M.

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neil wilkes

As an ex live engineer myself (retired due to injury), I cannot even begin to imagine why on earth I would ever want to use a perceptual (ie lossy) compression algo at a show!
Technically it would be easy to do, but WHY?
If I needed more punch in the low end, I used to have a feed into the subs from Aux1 on the desk, and wind in what I needed from the channel - so if I wanted a bit extra on the Bass guitar, or whatever, just dial it in from the Aux.

At a live show, you need all the poke you have. I certainly wouldn't shoot myself in the foot by throwing away 10/11 of my audio!

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