Yes indeed I stand corrected, I just had a good read through the datasheet and original patent docs and the 2044 is indeed a variation of the ladder type filter design. I need to do a bit of thinking
and possibly software simulation. From there I might play with a bread boarded design. My problem with using "special purpose" IC's
is that at some point they become vary hard to find and if the need replace becomes an issue thats where the pain starts. If a design can be kept to using readily available components, this situation can be averted. There are hundreds of bits of classic gear around the world currently being unused or parted out simply because of the lack of available components. To me this is really sad. As an electronics engineer I know anything can be replicated in one way or another. No it may not be the original design but if it produces the same functions this should not matter.
Many a Roland synth has been saved from the scrap heap due to a chap designing and building a pin for pin replication of the Roland filter hybrid.
I have quite a number of original SSM2044's and I have some of the ones available via hongkong. The ones from hongkong do indeed work but I have noticed quite a variation in output from them. Not knocking
them, just giving my opinion
cheers
--- In Simmons_Drums@yahoogroups.com, "spridleyman" <sprgroups@...> wrote:
>
>
> > filter, the internal circuitry of the 2044 is in fact very
> > similar to the SSM2040 and the CEM range of filters.
>
> No.. The 2044 is a sort of folded transistor ladder design, a
> sort of distant cousin of the Moog ladder (as used SDS3 & 4).
> The 2040 and CEM filters are cascaded OTA designs - not the same.
>
>
>
> Steve
>