[sdiy] SSM2040 vs CEM3320

René Schmitz synth at schmitzbits.de
Thu Nov 2 13:07:44 CET 2023


On 02.11.2023 11:15, Andrew Simper via Synth-diy wrote:
> I've already done detailed modelling on the SSM2040 and posted a video 
> to youtube on this model being matched to the LA67 Maca filter that 
> uses the SSI2140.
>
> Can you please post links to the internals of the CEM3320?

https://patents.google.com/patent/US4004141A/en

Its different from the 2040 in so far that it has logarithmic shaping 
before an OTA. ("linearising diodes")

The OTA core is very similar to the arrangement in the 2040. But the 
control and audio inputs are realized differently.

I've been pondering about this: How can this be patentable, if this is 
so similar in its working principle, and all the parts had been used 
elsewhere.


Best,

  René


>
> Cheers,
>
> Andy
>
> On Thu, 2 Nov 2023 at 16:44, Neil Johnson <neil.johnson71 at gmail.com> 
> wrote:
>
>     Hi,
>
>     Andrew Simper wrote:
>     >
>     > And a few patents referenced in the articles:
>     >
>     > Embley:
>     > https://patents.google.com/patent/US3532868A/en
>     >
>     > Buff:
>     > https://patents.google.com/patent/US4341962A/en
>     >
>     > Blackmer:
>     > https://patents.google.com/patent/US3714462A/en
>     > https://patents.google.com/patent/US4403199A/en
>
>     If you're hunting for patents to understand the SSM2040 then you could
>     start with the original patent:
>     https://patents.google.com/patent/US3969682A/en
>
>     For fans of the SSM2044:
>     https://patents.google.com/patent/US4404529A/en
>
>     Neil
>
>
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