[sdiy] SSM2040 vs CEM3320

[mark verbos]

Don’t you mean https://patents.google.com/patent/US4514704A/en?inventor=Douglas+R.+Curtis <https://patents.google.com/patent/US4514704A/en?inventor=Douglas+R.+Curtis> ?

I only say that because this is a filter and the one you posted is a “linear/logarithmic analog multiplier”
Anyway, cool stuff.


Mark




> On Nov 2, 2023, at 1:07 PM, René Schmitz <synth at schmitzbits.de> wrote:
> 
> 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 <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 <mailto: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 <https://patents.google.com/patent/US3532868A/en>
>> >
>> > Buff:
>> > https://patents.google.com/patent/US4341962A/en <https://patents.google.com/patent/US4341962A/en>
>> >
>> > Blackmer:
>> > https://patents.google.com/patent/US3714462A/en <https://patents.google.com/patent/US3714462A/en>
>> > https://patents.google.com/patent/US4403199A/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 <https://patents.google.com/patent/US3969682A/en>
>> 
>> For fans of the SSM2044:
>> https://patents.google.com/patent/US4404529A/en <https://patents.google.com/patent/US4404529A/en>
>> 
>> Neil
>> 
>> 
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