Spatial sound

["Bailey, Jim" <JBailey@corporate.southam.ca>]

Hello folks,

First off, let's get the spelling correct.

Secondly, I'm probably chiming in a bit late, and this is a slightly
off-topic subject, but I just wanted to add my tuppence to the pot.

OK, here goes:

>At 08:55 PM 11/3/99 +0000, you wrote:
(Sorry, I missed the original, so I don't know who "you" are)
>>....2 I've not tried this one. It involves placing a full range speaker
>>behind the audience and wiring it up to the two live terminals on a
>>stereo amp....

>Yeah, that's the setup Brian Eno described on the back of one of his 
>albums
>(I've forgotten which). 

On Land (Ambient 4)

>It does mess with the impedance, though, so be
>careful of your output transistors! The way it works is by phase
>cancellation;

I always thought it was much simpler, i.e. a potential difference (this may
amount to the same thing - most of the electronics I learned back in 
college
20+ years ago has long since flown the coop). A mono signal, dead centre
will present an equal potential at both hot terminals, and hence no current
flow. The greater the L/R difference, the more volume from the rear 
speaker.

>I had my stereo set up this way for most of the early '80's

>Tim

Me too. Back into the '70s too.

>I used an ancient spkr with a volume control  along with my hi-fi  for a 
>while, nice effect.

>Andy Butler

Ditto. I also had a little box made by Dynaco called a Quadaptor (still do,
as a matter of fact - should get it hooked up again). It essentially did 
the
same thing, but split the rear into two speakers with a resistor bridge.
There was a switch for shutting off the rear speakers, as well as a volume
control.

To bring this a little closer to the list subject, loops do sound great 
with
this set-up, especially if there is lots of panning. One thing I always
liked listening to, although it didn't actually use loops, is the beginning
of side 3 from "Tales From Topographic Oceans" by Yes. The xylophone and
drums seem to be flying all over the place! The effect of this set-up is
enhanced if listening is done in darkness, the darker the better, so that
there is little or no visual reference for sound location.

An easy way of simulating this arrangement can be achieved with open-air
type headphones (walkperson types are good, especially if they have their
own volume control). If the ear-pieces are placed slightly behind the ears,
one even gets closer to a 360 degree field. Of course this only works if 
the
speakers and headphones can run at the same time, or if the headphones can
run from an alternate source (tape deck, CD player, etc.). Adjust headphone
volume to taste.

Try it; you'll like it!

Jim Bailey

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