[sdiy] Weird filter in OB-Mx noise circuit

[David Cornutt]

On Apr 18, 2006, at 2:16 AM, mark verbos wrote:

>
> he's mixing the red and white noise together to get pink. I'm not sure 
> why he runs the red through a cap though. Maybe he just played with 
> the circuit until he liked the sound and then re-used it in all his 
> modules. It does change slightly from module to module. He simplified 
> the final stage for the OBMX.
>
>

I'm far from being a filter circuit expert, but I picked up on this and 
I
thought it was a bit weird: Because the PRN sequence is coming from
7400 logic, it comes out with a DC offset.  This isn't blocked until 
*after*
it has gone through the first filter stage, by the 0.1uF cap at C37.