[sdiy] Filter slopes

[Tom Wiltshire]

> On 11 Jun 2018, at 11:12, Guy McCusker <guy.mccusker at gmail.com> wrote:
> 
> On Mon, 11 Jun 2018 at 10:35, Tom Wiltshire <tom at electricdruid.net> wrote:
> 
> > On 11 Jun 2018, at 09:32, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> > 
> > For a practical implementation hunt out the Oberheim multimode filter circuit:
> > http://www.synfo.nl/servicemanuals/Oberheim/OBERHEIM_MATRIX-12_SERVICE_MANUAL.pdf
> > 
> > See page 4.
> 
> While the Oberheim is definitely the original source of this idea
> 
> I don’t know the dates of the various discoveries of this idea but Bernie Hutchins wrote an article on how to create various responses by mixing the stages of a four pole low pass in Electronotes 85 (1978). That predates the Oberheim implementations that I’m aware of but there could be more. 

Sorry, my mistake. In that case, Oberheim’s is just the earliest commercial implementation that I know about.

Bernie, did you come up with this, or were you inspired by something else?

Tom