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Physical modeling
While I understand completely the notion
of physical modeling as it applies to traditional
instruments (i.e. representing the length of
a trumpet, the materials of which it’s made,
differential equations of the wave motion,
etc), I have never understood what it means
to do physical modeling of an analog synthesizer
(for example, Yamaha claimed such for
the An1X).
What exactly is being physically modeled?
It seems to me that to do physical modeling
of an analog synth, you have to model such
things as the behavior of transistors, resistors,
capacitors, i.e. the electronic equivalent of the
length of the trumpet and its materials.
But I don’t get the sense that that’s what’s
10 VIRTUAL INSTRUMENTS
happening—it seems like they are just “modeling”
the OUTPUT of oscillators and so forth.
And if that’s the case, then the Yamaha DX7
was doing this kind of thing a long long time
ago.
David Jameson
via email
As your letter points out, it’s not a very precise
term. And let’s face it: it’s very difficult to
market a product just by saying it sounds good
and some rock star—who you’ve just eliminated
as a potential customer by making him or her
an endorsee—uses it. It’s far more interesting to
be able to talk about the technology. “We were
very careful to do an excellent job recording this
sample library using good mics” isn’t going to
turn a lot of heads.
So yes, we have seen “modeling” used fairly
liberally as a selling point. That was especially
true in the mid-’90s, when it was the buzzword.
Having said that, if the definition of PM is
using equations and algorithms to simulate the
behavior of a physical sound source, then what
Yamaha does did in the VL1 Virtual Acoustic
synth (which may have been the first commercial
synth to use PM) absolutely is physical modeling.
The VL1 uses Digital Waveguide synthesis,
which actually uses varying delay lines, and
Korg used it, and at one point Technics used it
in their WSA-1 synth.
Applied Acoustic’s Tasman synth and I’m
guessing Apple’s Sculpture (one of the synths
that comes with Apple Logic Pro, although
Apple only touts it as “component modeling”)
are two current PM softsynths that come to
mind. Modartt PianoTeq, reviewed in this issue,
uses PM to create its pianos, but the actual
technique is a closely held secret. My educated
guess is that if they haven’t licensed Digital
Waveguide synthesis, they’re using a different
variation of the Karplus-Strong plucked string
model, which uses a noise generator followed by
a filter with a delay feeding back into it.
Circling around your original question some
more, some instruments actually do model the
various circuit components of the product being
emulated. Universal Audio does that in their
plug-ins, for example. Whether a given softsynth
actually models the oscillator from the synth it’s
emulating is another question, but to me
absolute purity isn’t what makes a product
valid—it’s the bottom line sound.
Is FM synthesis physical modeling? Who
knows. What I do know is that a softsynth version
of the VL1 would be fantastic, because I
still consider it the pinnacle of synthesis in many
ways.
High praise
I just recently picked up your magazine
and am very excited about it. I am a police
officer that has patrolled the [withheld] area
for many years. I recently was injured and will
no longer be able to do police work. Music
composition has helped me through my rehabilitation
in many ways, and your magazine
has given me so much information on the
emusic world.
I know your mag is not necessarily aimed
at novices such as me, but please know that it
is making a difference for me. Even though I
don’t have any of the highspeed soft synths (I
use Cakewalk Sonar with its stock instruments),
with your help I am learning to get
the most out of what I have, and that is exciting.
I have a long recovery ahead that will not
be easy, but emusic is playing a big part in
keeping me positive and keeping my head on
straight, and your magazine is a big help.
Keep up the good work you are doing and
I can’t wait for the next issue.
Chris Watson
via email
This is one of the nicest letters we’ve received,
Chris. Thanks so much, and we wish you all the
best with your rehab.
The synths in Cakewalk Sonar are absolutely
nothing to sneeze at, by the way, in fact we
have a Very Deep Clinic about them in the
works And we certainly hope novices will enjoy
the magazine too. Our “First DAW” series hasn’t
gone away!