Korg Polyphonic Ensemble (was: Re: [sdiy] Secrets of Dan Brown's "The Buchla Code" Revealed

[Romeo Fahl]

I think you're referring to the PS3100 resonator:

http://machines.hyperreal.org/manufacturers/Korg/PS-synths/schematics/


On May 20, 2006, at 1:12 PM, Grant Richter wrote:

> Hi Jurgen,
>
> Hey, I could be completely full of it.
>
> I recall seeing a center tapped Vactrol in a Sallen-Key setup with 
> like 4700 pF and 1000 pF values used in some Korg design? There was no 
> 220 to ground.
>
> The Vactrol was a Hamamatsu and not a Perkin-Elmer.
>
> Yes, they added gain to the feedback amp. Why Buchla never did is a 
> real mystery?
>
> Do you have these published any place? I sorta think I saw them on 
> your site at some time in the last 10 years.
>
> Korg is my favorite MI company. They have made so many good keyboards.
>
>
> On May 19, 2006, at 7:28 PM, JH. wrote:
>
>>>> Also part of the filter for the Korg Polyphonic Ensemble keyboard 
>>>> was
>>>> lifted whole heartedly from the Buchla design (pretty sure the Korg
>>>> drawings have latter dates).
>>
>> Which part?
>>
>> The traveler is just a S&K VCF (no VCA switching as Buchla), with 
>> added
>> variable resonance (unlike Buchla).
>>
>> And the individual voices, yes that's LPF and VCA combined, but look
>> at this clever implementation, with simple BJT instead of expensive
>> Vactrols !!
>>
>> JH.
>
>