TRANSCRIPT SID CLASS 11-15-87:

Remember last week we talked about how
envelope voice settings should fit the
song and reflect the mood of the music.
If you can catch onto this trick, then
that's half the battle.

A trick to pass on is putting a rest
on each voice right before measure 
marker #1, before any music is played.
I usually use a half note rest for
this, but it depends on the tempo.  Use
a shorter rest if you're tempo is slow.
It gives a short pause before the music
begins.  This helps the player programs
"catch up", instead of jumping from
loading to instant play.  Be sure to
put the same rest on EACH voice,
however; if not, you're voices will be
out of sync.

Likewise, place a rest at the very end
of the sid, too.  This allows the last
note to fade naturally, instead of
being abruptly clipped off.  The rest
duration here depends on the tempo and
the release setting; if you hear that
the final note is still being clipped,
increase the rest duration at the end
of the sid.

Vibrato can be very important to your
envelope settings.  It can make the
sound more alive and natural.  But if
you use it, be sure to use it
correctly and make it FIT the envelope
you've chosen.

Vibrato can be set separately on each
voice, and it requires two separate
commands.  The first, VDP, sets the
vibrato depth.  The second, VRT, 
specifies the vibrato rate.  There are
no default vibrato settings, so the
first time you turn it on you should
use both of the above commands.  To
turn vibrato off, use VDP 0.

These two commands require some time
experimenting to get the affect you
want.  An easy way to begin is:
VDP 8     VRT 2
Notice how this sounds, and increase
or decrease the settings to achieve
what you want.

A trick used by many Sid Artists is
to increase the vibrato as a note is
sustained.  For instance, if you have
a sustained whole note, turn off the
vibrato <VDP 0> at the beginning of
the note, then split the whole note
into four tied quarter notes <or eight
eighth notes, if you prefer>.  Turn
the vibrato on right before the second
quarter note is sounded <remember to
use both commands>, and increase the
vibrato before each successive note.
This trick requires some time, but the
effect can be dramatic.  An example
of a sid using this effect is:
cry/river.mus.  Load the .mus file into
the Editor and see how this sid was
set.

The pulse width command <P-W> should be
used with the pulse <P> waveform.  It
has no affect on sawtooth, triangle or
noise waveforms.  The default P-W
setting is 2048 <this setting is a
perfect "square wave">. Try using
different P-W settings to hear the
different values they produce.

Values smaller or larger than 2048
produce rectangle waves.  The farther
away the value is from 2048, the waves
become narrower and the volume begins
to decrease.  The pulse wave is
inaudible when the P-W is set at
either 0 or 4095 <the smallest and
largest values>.

Remember, each voice can be set
separately with its own envelope.
For instance, if you use a P-W value
of 500 on your lead voice, and a P-W
value of 2048 on your bass voice then
the bass will overpower the lead voice.
The total sound shouldn't be flat, but
with depth.  The lead voice should be
in the foreground, easily noticeable.
The ryhthm or accompaniment should be
in the middle ground -- it's there for
a reason, but it shouldn't compete
with the lead.  Bass is in the
background.  P-W settings can help
you achieve this.

Volume cannot be set separately on
each voice.  It is set on one voice
only.  The default volume <VOL> setting
is 8.  Try not to use VOL settings
above 12, even though the master volume
can go to 15.  A setting of 15 can
distort the sound on some speakers.
It doesn't matter on which voice you
set the volume, but set it on one voice
only.

Last week we began discussing repeats
used in music.  The HED/TAL command is
used for a simple repeat. However,
often you'll find the repeat has a
first and a second ending.  This means
that one set of notes should be played
at the end of the sequence the first
time through and the second set of 
notes should be used as the endind the
next time through.  The HED/TAL cannot
handle this kind of repeat.

For this, we need to DEFINE A PHRASE.
If a simple repeat is like a loop,
then a defined phrase is like a
subroutine.  It is defined, and called
when needed. DEF/END/CAL are the 
commands.

To define a phrase, enter the DEF
command.  This command needs a number
<any DEF number value above 15 is
"enhanced" and the public domain
players cannot play it>.  Caution:
each voice must have it's own DEF
number value.  Do not use DEF 2, for
instance, on all three voices because
when DEF 2 is called all three voices
will call that same phrase.

DEF is placed at the beginning where
beginning repeat symbol is found.  This
marks the place where the music will
jump back to in the repeat.

After the last note of the phrase and
before the first ending of the repeat,
place the END command.  It has no data
value, so enter it by typing any
number.  This marks end of the
definition and the notes are ready for
calling.

To call the phrase, enter the CAL
command.  The CAL is placed immediately
::before:: the second ending notes.
It calls the phrase that you defined
with the DEF command and uses the same
data value you used for the DEF value.

Example:  DEF 0 is entered at the
beginning of the repeat.  Playing
continues, encounters the END command.
This has no affect until the phrase is
called, so playing continues on into
the first ending of the repeat.  The
command CAL 0 sends the playing back
to the beginning of the repeat, where
DEF 0 is marked. Playing continues
the second time until it reaches the
END command and jumps to where the
CAL 0 was entered and plays the
notes following CAL 0 -- the second
ending of the repeat.

A phrase can be called as many times
as needed. It's still defined after
it is called, and you need not 
re-define it.

Defined phrases have many more uses
than besides repeats.  If you want to
change envelope settings back and
forth within a song, you can define
the envelope settings and call them
wherever needed.  Any voice can call
a phrase from any other voice that has
defined it.  However, don't define
several phrases <such as envelopes>
at the beginning of a sid before any
notes are played.  It can result in
a "clobber" error.  A phrase really
shouldn't be defined until the first
time it's needed.

Since we've run out of time tonight,
tempo restrictions will be taken up
at the next class.  :)

