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[Dan Mortensen]

I'm going to be involved with the Historical Track again at the next NYC AES Convention, and we are in early discussions with some guys who want to do a talk and demonstration about early Quad stuff. The question is about reproduction in a Javits-sized presentation room, which probably seats around 150-250.

All the Quad/Surround speaker demos I've heard have used direct radiator speakers. Since direct radiators don't have much projection, the middle of the room has had a very small sweet spot. Anywhere else in the space, the listening experience is deeply colored by whichever speaker you happen to be closest to, so my experience in those demos has been less than impressive.

My thought is that because the direct radiators are essentially covering near field only, only people equidistant from all the speakers are getting the effect. Those closer to any speaker are in that speaker's near field but in the far field for all the others.

It would seem like getting all listeners in the near field of every speaker would be advantageous which I think means using all horn-loaded speakers or line arrays. Since line arrays have arrival time issues in the extreme near field, it seems like that argues for all horn loaded, like Meyer MSL4 or similar.

Do you agree, or are there other solutions not as large as MSL4's? Oh, and quad headphones and overhead speakers are likely not options.

I guess the nub of the question is: How to enlarge the sweet spot to cover most or all of a listening space holding 100-200 people?

Thanks!

[Justice C. Bigler]

Use one of the more modern psycho-acoustics driven immersive audio systems such as L-Acoustic's L-ISA system.

[Tim McCulloch]

Hi trim, aim down.  The more equidistant you can make the listener/source the more uniform the effect's perception.

Being old enough to remember "quad" the first time around, the sweet spot was very small if you were hoping for concert hall sound.  If you were listening to material written/produced to exploit the medium the sweet spot was larger and more folks could hear the program as intended. 

[Dan Mortensen]

Use one of the more modern psycho-acoustics driven immersive audio systems such as L-Acoustic's L-ISA system.

This specific event is to show the state of the art in 1970. While the L-ISA blurb sounded interesting "...is a panoramic, multidimensional sound experience delivering stunning, clear, natural audio that is correctly localized to sound sources. Concertgoers have described it like feeling they are “inside the music”", the full description of how it works

"1. Set up a point to point connection from a DHCP enabled laptop to the L-ISA Processor.
2. Use the L-ISA Controller software and follow the instructions described in the Help menu."

The End.

was not.

[Dan Mortensen]

Hi trim, aim down.  The more equidistant you can make the listener/source the more uniform the effect's perception.

This is very good advice, but of course the speakers in the rooms are all on sticks. Maybe as high as 8'.

There may be nothing that can be done to make it better in the current instance, but I thought I'd ask about the theory as transformed into practice to see what people have done.

How did the several Pink Floyd surround events work? Anybody hear them?

[Chris Hindle]

This is very good advice, but of course the speakers in the rooms are all on sticks. Maybe as high as 8'.

There may be nothing that can be done to make it better in the current instance, but I thought I'd ask about the theory as transformed into practice to see what people have done.

How did the several Pink Floyd surround events work? Anybody hear them?

I'd be inclined to take the demo outdoors, where you could get some distance on the speakers.
More distance to the listeners would give a bigger "sweet spot".
MSL-4 would do quote nicely....
Not just Floyd, check out The Who Quadrophenia tour.
i *think* Bob Heil had something to do with it.
Chris.

[Rick Earl]

This is very good advice, but of course the speakers in the rooms are all on sticks. Maybe as high as 8'.

There may be nothing that can be done to make it better in the current instance, but I thought I'd ask about the theory as transformed into practice to see what people have done.

It's at AES, as a historical tract, it seems to me you could get a manufacturer to help sponsor the event and get what is needed to make it work.  I have attended other presentations that have used other than just the house AV because of their needs.

[Art Welter]

How did the several Pink Floyd surround events work? Anybody hear them?

Didn't get to hear them, but basically sound effects like helicopters, chiming clocks and gongs were routed through an approximate diamond layout, with one stack at the rear facing the stage, the two side stacks to either side, with the mains PA handling the front of the "quad".

The effect send was routed through a joy-stick quad panner, a lot easier to control than using four separate rotary knobs, like most of the rest of us had to use for that sort of thing 

I was offered what was purported to be one of Floyd's former Midas consoles with a quad panner for sale in the mid 1980's, but passed- other than the joy stick it was very basic in terms of EQ and routing compared to what the "state of the art" had evolved to.

[John Roberts {JR}]

Good luck, there are probably multiple different technologies lumped together as Quad-Surround sound (I designed some consumer surround sound gear back in the 80s).

Consumer gear is intended to work well for a modest sized sweet spot in consumer listening rooms. While everybody envisions dramatic helicopter flyovers origination from behind the listener this is only fully realized with later discrete 6 (7?) channel systems.

Further there is a theater delayed speaker reinforcement technology where the goal is not to hear the sounds coming from the surround speakers, but making them  sonically invisible as discrete sources, while providing rich ambiance with them.   

In both systems the rear speakers are delayed relative to the front speakers so the listeners localize the sounds as originating from the front (movie screen or video monitor).

If you are going for "gee whiz", look for some discrete quad Pink Floyd surround effects tracks. Of course you should be able to impress some audience members by demonstrating how ambiance disappears when conventional rear surround speakers are muted, and then returns when unmuted.

JR

[Randy Pence]

MIght be useful to get in touch with Francois Kevorkian. He currently does a bit of studio work to do surround music and lives in nyc.

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