[sdiy] On cloning, and the Oberheim VCO

[Aaron Lanterman]

On Apr 15, 2008, at 12:00 AM, mark verbos wrote:

> I'd suggest you look at the Kobol oscillator on my page
>
> http://www.simple-answer.com/DIY.html
>
> It's basically the same one that's in an SEM, but with OPamps  
> instead of those transistors for that buffer. Sadly, you'll notice  
> that it uses wider supply rails than +/-15, like the SEM. They also  
> used a 3086 for the NPNs in the core.
>
> Incidentally, Q4 does not invert the signal. Q5 and Q6 are a  
> comparator, R29 is adding positive feedback for hysteresis, Q8 and  
> Q9 are switching not buffering.
>
> My guess is that they used transistors because they are small and  
> cheap. It's probably a fatter, driftier sounding oscillator for it.  
> RSF used SSM chips in every part of the Kobol except the oscillator,  
> it's a GREAT sounding box.

Excellent - I guess you got this running without any troubles?

- Aaron