                         DOLBY SURROUND AT WIRED 95

  A text for musicians and sound-engine coders...
  Please read an important note about soundcards at the end of this text.

  Wired'95  will be the next party in Belgium, organized by Antares, Imphobia
and some members of TFL-TDV, like me...  It  will  take  place in the city of
Mons, in the university rooms, from the 3rd to the 5th of november.

  I  would  tell  you  about the sound equipement that will be  used  in  the
comporoom(s) :  kind of  Dolby Surround system  with  3 speakers  (min. 1000W
each) + subwoofers on  the screen side for classical stereo,  and  -at least-
10 mid-power  speakers  all around the room  (back  and  side)  for  surround
effects.
  The comporoom will be a  big lecture hall,  with confortable seats and ama-
zing projection screen (see Wired 94 reports in Imphobia 9). Some people have
written last year that Wired 94 projection room  had the best quality of pic-
ture ever seen at a party ! My wish for this year is that people say the same
thing about sound.

  So I rely on you,  music makers,  to make  stuffs  that will exploit it the
best way !
  Here are some advices to make your work sound even greater on it:

  -Try not to play every  sample  just on  the  left or right channel but use
also center or  -better-  most panning position  between  full  left and full
right.  There are two reason for that. First: there will be  a  third speaker
for center.  So  even  people  who are sitting on the side of  the  hall  can
hear  sounds coming from the center of the screen. Second: full left and full
right sounds  are  also  reproduced by surround  speakers,  but  less  loudly
than surround effects.  It means that, even if you don't use surround in your
song,  there  will  be  a  distinction between the front and  rear  speakers.
Only the center sounds are coming only from the screen; the others are coming
from everywhere in  the  room  -with a domination of left or right.

  -How  to  make  surround  effects in your modules ? You can of  course  use
the  ProTracker  surround command, but no player could play it on  GUS.  Only
MOD and AMS  have  that command anyway (I  heard  that  it  was  8FF  but  it
doesn't  seems  to  work !?). The best way is to use two samples  like  this:
One  sample  must  be EXACTLY the same than the other one, but negated. 

 (no surround command needed) 

   ..   Sample #1         Sample #2
 I .  .   .         I      .         
 I=====.=.=.=>      I=====.=.=.==>
 I      .           I .  .   .    
 I                  I  ..         

Your  ears  won't hear the difference between  those samples, but if you play
them exactly  at  the  same time, one full-left and the other one full right,
you will get the REAL surround effect. With a  Dolby processor  or  with  the
system that will be used  at  Wired95, they will be heard from the rear spea-
kers (= surround speakers) ! Of course it  takes  a  bit more memory, but the
result is so good , even if you do not have a surround system at home to  ear
it ! 

  Physically, one sample is negated in relation  to the other one. You can do
this with  the  "negate"  function  of many  editors  (that's not the signed/
unsigned function ! ) or write a  very  simple program to do it. I personnaly
do apply a volume of -100% on the whole sample with FT2 (you can do this then
save the sample and load it with ST3, of course, but don't forget the " PC <>
Amiga " conversion then !).  

  There is just a little problem  with this  method : If you play your module
on a mono card, the result of  playing both  samples  on  the same -and only-
channel will be... no sample heard. If you make a stand-alone module for  the
multichannel competition, that's not a real problem, because  I  don't  think
that  mono-card  owners are big module listeners.

  If you make your module for a  demo, you  can  do like me: I reserve one or
two tracks  for  surround  FXs. One  of  both  samples used to make it is al-
ways on a "surround"  track.  So, when the demo detects an  old mono card, it
just  has  to  mute this -those- track(s), and only one sample will be played
so there  will  be  no problem. You  can  also say : " Fuck mono card owners,
they won't hear  some samples, that's all !", It's easier, of course.
 
  - Don't use surround for "extreme-bass" sounds (like those you could use to
make the seats vibrate :-) ), because in a "normal" 2-speakers stereo system,
the negation of low frequencies do happen in the air.  This  means  that  you
could loose some bass.

  - AESTETICS OF SURROUND. As the word "surround"  says,  it is more made for
ambiance sounds than for rear  effects like  spaceships  heard  in your back,
etc. One proof of  this  is  that  the surround   effects   are  always  less
bright than front effects.  Anyway, it is  always  funny  to make sounds pass
from rear to front of the room :-)... 


                           PROBLEMS WITH SOUNDCARDS
                           ------------------------

  The PC used for the demo/intro compo projection will have both GUS and SB16
soundcards. Your demo can use any of them.  For the music compos ,  GUS  will
normally be used,  but you can ask us to play your module on SB16. This para- 
graph explains some reasons of such a request:

  When  you  play  the  same sample on 2 channels on a GUS, there is always a
short delay between the two voices. It is too short to ear a real "echo", but
it can modify the sonority of that sample  (especially with FT2, because with
it the delay is can vary ...). It is quite a problem for making surround like
I've explained upper : if you try to play the inverted samples on L & R chan-
nels with a GUS,  they  won't  overlap exactely. If you put your amplifier in
mono  mode,  you  should  normally not ear those 2 samples (as I've explained
upper...),  But  on  a  GUS , there will be a bright residual sound. More the
delay is long, more the residue is loud. If the residue sounds nearly like the
original  sample,  it means that the delay is so long that both samples don't
overlap properly and the surround effect should be poor. It depends of the
player, in fact, and maybe of the computer.

  So, IF YOU'VE MADE YOUR MODULE WITH A SOUND BLASTER PRO OR SB16, and...

  - if your module plays the same sample, with the same pitch, and at the
    same time on 2 different tracks,

  - if you use stereo samples,

  - if you make surround,

  you should better listen to it on a GUS (on a DX2-66 if you can) before the
party, with the player that we will use (see last invitation file), so if you
don't like the way it sounds, you could ask us to play it on SB16.


  Well, that's all for the moment, I hope you will be a lot of musicians and
audiophiles  at Wired 95  because I did the maximum  to make you  enjoy  the
compos !

  You can contact me if you have any questions about anything.


                                                       "Magic" Fred /TFL-TDV 
                                                         Wired 95 organizer
                                                        responsible of sound


Email: llardin@is1.vub.ac.be (leave "4Fred" as comment)

Phone: +32-2-3747442 ask for Fred
       (French or English)

Snail: Frdric Scalliet
           53 Dieweg
         1180 Brussels
            Belgium
