MOTM

> No matter how good a modular simulation can get, it is not going to be real.
> At least as far as I'm concerned.

Well, I think that you're dead on from an interface point of view.  From
a sound point of view, you're also right - not forever, but probably for
a good few years yet.  Let me explain why I think so.  I apologise in
advance for the length of this, but this sort of issue is a large part
of why I just forked out a few thousand for a MOTM rig, so I care about
it a lot...


It's not the sound of oscillator, filter or whatever that can't be
handled digitally; all of these can be replicated if you throw enough
effort at it (though arguably, no one has yet).  The real shortcoming is
a little less obvious - software modulars suck at audio rate modulation. 

The obvious way to write a software modular is to represent each module
as an object.  However, calling an object's method that generates the
next bit of audio incurs an overhead (saving registers, setting up stack
pointers etc...).  In order to amortise the cost of method call, they
typically pass audio around in blocks of around 50 to 100 samples at a
time.

None of that makes audio rate modulation impossible - in fact it's easy
- but it all falls down when you consider audio modulation in feedback
loops (for example where A modulates B, which in turn modulates A,
though it may be less direct than this).  In software, the only way to
handle this is to spot that there is a feedback loop and to insert a
delay into the feedback chain which buffers the audio at that point
until the next time that the synth evaluates all the modules.  It's this
delay - where all your audio modulation in feedback loops is delayed by
100 samples or so - that kills you.

Of course, if you throw enough CPU at it, you can just brute-force the
problem and swallow the method call overhead.  Then you can pass audio
round in single samples instead of blocks.

That's still not good enough.  

When I was still unsure as to whether I was going to buy a MOTM, I went
round to Robert Rich's house (since I live in the same town and he's a
VERY nice guy who didn't mind a total stranger phoning him up) and he
showed me a chaotic patch with two oscillators soft-synced to each
other, each being additionally modulated by noise.  (Great patch,
BTW!).  To do this properly in the digital world, you not only have to
pass single samples around, you probably have to do it at something
extreme like 200 KHz, converting back to 44.1 KHz at output.  (The exact
freq you'd need for this would depend on how fast the soft-sync part of
the MOTM's oscillator reacts).

Now, modern CPUs are fast, but they're not fast enough to run really
expensive oscillator and filter models at 200 KHz, passing round a
single sample at a time.  And they won't get there for a few years
yet...  


Harry

p.s.  I love digital too, but I don't want it trying to be analog when
analog does it better.