[sdiy] Good 24db/oct HP-LP-BP-Notch filter Schematics ??

[Mattias Rickardsson]

On 6 March 2014 00:27, Tom Wiltshire <tom at electricdruid.net> wrote:
> "The RS110 consists of a two channel audio mixer followed by four, parallel, resonant filters with voltage controlled frequency and a unique "insert" point in the feedback path that generates and controls resonance."
>
> Now, I seriously doubt that there are genuinely four separate, parallel 4-pole filters on that PCB. Although that would be one way to do it, it would be very inefficient. So what exactly *are* they talking about?
>
> My bet is a simple 4-pole Moog-style ladder (hence the talk of a "discrete" filter with "no filter chips") with several mixers doing pole-mixing to get the various responses (that's the "parallel" part).

Yes, the "four, parallel, resonant filters" bit probably just means
four *simultaneous* resonant filter outputs.

/mr