The Surround 2001 Conference by Barry Ober

The SURROUND 2001 CONFERENCE sponsored by Surround Pro Magazine, was held at the Beverly Hilton Hotel in Los Angeles on December 7 and 8, 2001.

Reading like a mini who's who in audio, a slew of producers, engineers, acousticians, film editors, recordists, mixers and assorted scientists gathered in a smallish, rather intimate setting (there were 28 booths and 6 meeting rooms) to discuss the particulars of Surround Sound.

Only the third annual show of its type, it brought together in a convenient and accessible format a series of experts lecturing to a series of experts - a busman's holiday of audio intelligentsia, as it were.

There are a number of critical issues that seem to surface every time we talk about the evolution of stereo into surround sound. Not unlike the evolution of mono into stereo, the finer points of mixing, panning, bass management, speaker placement, movie theater vs home theater, disc formats and the alphabet soup of formats themselves, from THX to DTS to Dolby to LFE, to SACD to DVD, to DVD-A and so on, became the critical issue of the day.

While some of these topics might seem simplistic in retrospect, say, 20 years from now, I assure you that they are of utmost criticality right now, and large sections of the industry seem to hang on every word spoken in some of these seminars.

For instance: for years, stereo panning for the home pop recording market has used two channels, the Left and Right. The center image is totally phantom, obtained by panning essentially a mono signal to be the same strength in the Left and the Right speakers, and psychoacoustically we think there is an auditory image in the center. With the various surround sound formats, we now have a true center channel speaker to work with. Do we pan evenly between all three speakers? Do we set up dual panpots to pan between Left and Center and then from Center to Right? Or do we place the center sound in the center speaker only, and feed "a little reverb return" to the Left and Right speakers? Or do we hope the consumer has the system set up properly in his or her home, and we feed some balance of signal to all three speakers? And if we mix it that way, what will it sound like when it is "folded down" into stereo? Will we have to do a completely separate mix for a "stereo CD" release and then do a separate mix for a "DVD-Audio" release?

Speaker placement is another hot topic. Starting with the ITU suggested specifications of stereo placement, (which has been slightly modified/embellished by the AES PDF HERE) and adding to that various recommendations from Dolby and THX, and adding to that the real-world setups that professional engineers somehow "fall into," we have a series of guidelines that have been stretched almost to the breaking point. At face value, each of the systems and setups makes sense - or seems to.

Then someone comes along and suggests or explains in great detail why the other system is kind of "wrong".

Some of these systems do play well together. Dolby and THX coexist just fine on the playground, but everyone has an explanation of why you should or shouldn't use dipole surrounds, and perhaps in another paper I'll expound on this. At least it was agreed upon, more or less, that the technically correct way to set up the LCR speakers is to have them (more or less) each the same distance from the sweet spot, which can be defined as an arc (more or less) the radius of which is drawn from the listener's nose.

At least nearly everyone agrees on 80 Hz as the crossover freq between the mains and the subwoofer(s). Since there are MILLIONS of homes which have a receiver/control center with THX circuitry in it, and that circuitry crosses over at 80 Hz, if you are doing a studio mixing session and you want to hear the mix the way your target audience hears it, then you should use 80 Hz as the crossover frequency. True, in special and certain instances there may be reasons why exactly 80 isn't right. Too high a crossover frequency, and you run the risk of hearing the bass directionality. Too low a frequency and you lose all the benefits of proper bass management, which include increased dynamic range from the mains (satellite speakers) and less dopplering of the mid frequencies by the low freq drivers.

The ubiquitous acronym LFE is yet another issue. Originally designed for film use only (!) for increased headroom in the optical channels, somehow this effects/extension channel is being used / abused by music mixers trying to squeeze every last dB of sound into every last molecule of track headroom and dynamics, which brings up another problem, namely "FF distortion". Recent papers presented at AES have shown that most CD players can be in a permanent state of distortion when reproducing new album releases. How is this measured? And what do we do about this after we measure it?

To balance out the show we had proponents of other psychoacoustic delivery systems on hand to give their viewpoint, from the people at SRS Labs to Richard Elen on Ambisonics. Notably absent this year was the contingency from Lake systems / Dolby Headphone.

Vincent Van Haaff of Waterland Designs spoke on the acoustic factors you should take into consideration when designing a studio / control room / monitoring environment for surround sound, while Art Noxon from ASC discussed setting up Tube Traps specifically to enhance surround speaker setups, in a combination called "Attack Wall".

Bob Michaels of 5.1 Entertainment spoke about the basic differences between DVD formats, and how different authoring software is necessary to complete a project so that whether the disc is played on a DVD-V player, or a DVD-Audio player it will have the correct menuing system appear. This is apparently a rather large bottleneck in the production of DVD's, and has opened up a whole new field of software and production called menu authoring.

John Eargle discussed the new realm of microphone setup and technique for surround sound recording.

Tom Holman gave his historical perspective and dropped hints about the future of the industry.

A lively discussion was had with Joe Bates of the CEA moderating on whether or not the typical consumer can hear the difference between Dolby Digital 5.1 and DVD-Audio; and of course this only raised a hundred other questions such as the technical setup and validity of the test, how was the original material recorded and monitored, and so on.

There were two sessions concerned with film; one was about mixing surround for film in the theater, hosted by Chris Jenkins of Universal Studios, and the other was about mixing film audio for DVD presentation in the home, which requires a whole different set of rules and assumptions, moderated by Bob Margouleff, Brant Biles, and Steve Parr.

To round out the format wars Bruce Botnick and Frank Fillipetti hosted a discussion about SACD and DSD.

Bobby Owsinski from Surround Associates and Surround Professional Magazine lectured on System Calibration and Bass Management, explaining how in the real world of studio setups sometimes the hard and fast rules have to be bent a little bit, while in another session, recording studio managers from around the country were discussing the requirements and hardships of owning and booking a recording / mixing facility which has specifically been designed for surround sound work. John Kellog from Dolby Labs discussed interfacing with the artist and making the artist and musician aware of the technical /creative oppportunities that surround mixing has to offer.

The Steinberg Producer group, partnered with DTS, discussed their views on the innovative new NUENDO digital audio workstation and how it is used as a creative production tool. Industry luminaries such as Greg Ladanyi, Elliot Scheiner, Phil Ramone, Chuck Ainley, Ed Cherney, and Alan Parsons gave their views.

A panel of car audio experts discussed the latest in car surround, and what technical breakthroughs or setup adjustments make the car environment different from the home environment.

In another room, the world of 5.1 as it relates to the HDTV spec was being discussed. Various methods and procedures for setting up, feeding, and mixing multiple audio sources to multiple audio destinations were explained.

And now, rather than have me ramble on endlessly I'd suggest you read all about it right from the source. SMR group (Stuart M. Robinson) has put together a beautiful site and explanation of the show which you can find HERE.

 

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updated 11/11/04