The Yamaha AN1x Synthesizer mailing list

I would like to use the Free EG to make the fine tuning of each 
oscillator drift independantly.  Does anyone know what a graph of 
real oscillator drift would typically look like? (I'm sure it varies 
from VCO to VCO.) Is it pretty much sinusoidal with just a few 
eccentricities or is it more "squiggly"/random than that? (I'm 
guessing that I should use a full 12 or 18 second free EG length.)

Now you've gone and dipped into the pool of the unresearched.
How do analog oscillators drift, and where do we find that data?

The worstest thing about random is that computers don't like random.
IIRC, the AN1x doesn't have a random function for any parameter.

I've tried this idea with a couple of samplers.
It can be pretty interesting if there is a random function.
If not, it can sound a lot like looping.

One idea is to map velocity or key to change the envelope generator in some way.
Sort of pseudo-random will result.

Ed Edwards
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> -----Original Message-----
> From: Dan [mailto:dxalgorithm18@...]
> Sent: Thursday, March 03, 2005 5:50 PM
> To: AN1x-list@yahoogroups.com
> Subject: [AN1x] OSC. Drift
>
>
>
>
> I would like to use the Free EG to make the fine tuning of each
> oscillator drift independently.  Does anyone know what a graph of
> real oscillator drift would typically look like? (I'm sure it varies
> from VCO to VCO.) Is it pretty much sinusoidal with just a few
> eccentricities or is it more "squiggly"/random than that? (I'm
> guessing that I should use a full 12 or 18 second free EG length.)
>
>
>
>
>
>
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Ed Edwards wrote:

> Now you've gone and dipped into the pool of the unresearched.
> How do analog oscillators drift, and where do we find that data?

The data are out there. Try http://scholar.google.com/ and search for
"oscillator drift" or "thermal drift". After reading all those links,
you should ask for college credit!

> The worstest thing about random is that computers don't like random.

I'm not a mathematician but I play one on the computer... 

Computers are deterministic machines, that means generally when you ask
it to do something then it will always produce the same result. So
getting it to be random, or to produce different results based on the
same input, is difficult. The best we can do is to use Psuedo Random
Number Generators (PRNGs).

A PRNG will produce a long list of numbers. However, the list never
changes. So, to appear random, you need to select a different starting
place on the list each time you read it. Your starting place on the
list is called a seed value.

Seed values are usually chosen based on something always changing like
the current time, line noise, or even a lava lamp!
(http://www.wired.com/wired/archive/11.08/random.html )

> One idea is to map velocity or key to change the envelope generator 
> in some way. Sort of pseudo-random will result.

Since humans never hit a key with the same force (except when emulating
Jerry Lee Lewis's "Great Balls of Fire"), I think velocity would make a
good seed value!


=====
-- 
Kevin Conder

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