[sdiy] ... Simulating a Moog

[Peter Grenader]

Julian Bunn wrote:

> Hi Peter,
> 
>> john mahoney wrote:
>> 
>>> It occurred to me that, given the circuit diagrams for e.g.
>> a Moog, and a
>>> lot of free time, one could enter everything into Spice and
>> completely
>>> simulate the behaviour of the instrument. With the results
>> you could make a
>>> faithful digital reproduction of the Moog. And you'd never
>> need to touch a
>>> soldering iron J
>> 
>> 
>>> From my experience working for a speaker company that used
>> it a lot in
>> engineering, Spice at best simulates and is better for determining
>> parametric ranges than acoustic properties.
>> 
>> Then, what happens when certain older than sin parts have no
>> Spice model?
>> It then goes into the 'create life' as the first process step
>> kind of deal
> 
> I think you'd have to look for equivalents, or in the worst case
> develop your own simulation of each. I doubt there is a Spice model
> for the SG3402 ring modulator chip used in the Minisonic, but this
> chip behaves in a very easily modelled way. A lot of work though,
> nonetheless.
> 
>> 
>> But let's say one pulled it off, then everything you want to
>> control it with
>> would also have to be within the spice realm  And assuming
>> you got those
>> other circuits successfully replicated as well, for the $$
>> you'd have to
>> shell for a computer powerful enough to handle the size of
>> the now 'patched'
>> spice model for the standard synth VCO into LP into VCA
>> oldie,  you could of
>> hired a team of solderists to do the work for you!
> 
> The hope would be to come up with a parameterization of each
> module's output based on its input. This would just be a matter of
> fitting the input and output curves with a polynomial, for example. Once
> you have the transfer function for each module in this way, you can discard
> SPice and just solve any given module configuration analytically
> very fast ... in real time on a decent desktop I guess.
> 
>> 
>> Plus, it's sort already been done with DSP anyway in regard
>> to the Moog:
>> 
>> http://www.moogmusic.com/detail.php?main_product_id=90
>> 
>> does it sound anything like the real deal?  Nah....but it's
>> fun.  Notice
>> their official description eludes to this:  "Software
>> Synthesizer BASED on
>> the classic Moog Modular Synthesizer. "
>> 
>> - P
>> 
> 
> That looks like a fun product! I wonder how they did it, and if
> it doesn't sound like a real Moog, where did they cut corners or
> go wrong?
> 
> Julian
> 


Well,

Adding polyphony and a digital delay module are two biggies on the list.
Plus, the filters aren't the same, although they sound great on their own.
It's a lot of fun - it's doesn't sound like a Moog.