Organization: The American University
Newsgroups: bit.listserv.emusic-l
Date:         Tue, 17 Nov 1992 12:58:17 EST
From:         ronin <HARNDEN@AMERICAN.EDU>
Subject:      bubbles
Comments: To: EMUSIC-L@american.edu

i got a little tired of strictly gearhead jabber, so i thought i'd
blather a little bit on recent programming stuff... of which i,
for one, would certainly like to see more on this list. i'm not
a plug-it-in-and-jam-on-it kinda guy. i wanna tweak. you wanna tweak?

anyway... i was feeling bored and found myself tearing apart a factory
preset called 'bubbles' on my roland jx8p. it sounds like chorused ticking,
which because of the peculiar resonance of the jx's lopass filter really
does come off as kind of 'wet'. i couldn't figure it out, though, because
the jx's lfo isn't like, routed to trigger an envelope or anything, so i
couldn't see what would produce what sounds like a continuous repetition
of short, transient events. the other thing i thought was that the mix (the
balance between the two dcos) might be being swept by a sawtooth lfo, quickly
shifting between a pulsewave and silence (with the second dco's input to
the mix turned off). nope. then (aha) i looked at the dco and found that,
not only was its offset frequency set as low as it could go, but that
one of the two envelope generators was being inverted and used to drive it
even lower. so the ticking was that dco going subaudio. clever. that
envelope had an adsr like:
a=instant
d=zip
s=max
r=really long
and the second envelope generator simply controlled the output vca, with
a shorter release, so that you don't really hear the subaudio wave increase
in frequency as the sound fades. quite nice.
so... i tried to replicate it everywhere else. the prophet 5 was easy. one
of its oscillators can simply be set to subaudio, and still be allowed
to track the keyboard. the alpha juno 1 was a little different. it only has
one envelope generator, so while the basic control route is available (i can
apply the inverted envelope to the dco), the rate of the ticking increases
as the sound decays. not the same, but actually sort of interesting on its
own. the oberheim matrix 6, now... that was another story. i have often been
impressed with its control flexibility (if not its sound), but seem to have
found an odd limitation, here. the digital control values that you see when
you perform an edit on the instrument actually represent the full range of
operation of the parameter being edited. so, when i begin by setting the
dco's offset as low as it will go... that's as low as it will go. the
application of another control voltage (like from an inverted envelope)
has no effect. it does in fact go subaudio, but only on a small portion
of the lower end of the keyboard, so it's pretty limited. now, noting
that it does respond to that keyboard control, i haven't tried sending
it a transposed-down keyon to see if it will track even lower... but
i bet it won't.
oh, yeah... i also tried it out on the moog 55. needless to say,
no problemo, although i did discover that, the way those oscillators
are coupled to the system, i preferred a triangle as my subaudio
click, rather than a pulse. i actually got a double-click off the
pulse, as both the positive- and negative going cycles had sufficient
'ring' to punch through the filter.

-----------< Cognitive Dissonance is a 20th Century Art Form >-----------
Eric Harnden (Ronin)
<HARNDEN@AUVM.BITNET> or <HARNDEN@AMERICAN.EDU>
The American University Physics Dept.
4400 Mass. Ave. NW, Washington, DC, 20016-8058
(202) 885-2748
---------------------< Join the Cognitive Dissidents >-------------------
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU