[sdiy] Korg MS-50 VCA and VCF

[Harry Bissell]

The CA3019 was readily available at that time and had excellent matching
due to monolythic construction. It was used in many 'ring modulator' type
circuits at the time. A natural extension would be to use it as Korg did.

BTW, you could use the CA3046 transistor array as diodes in a similar
fashion. Just watch the substrate...

H^) harry


----- Original Message -----
From: JH. <jhaible at debitel.net>
To: Aaron Lanterman <lanterma at ece.gatech.edu>, synth diy <synth-diy at dropmix.xs4all.nl>
Sent: Fri, 30 Apr 2010 04:37:13 -0400 (EDT)
Subject: Re: [sdiy] Korg MS-50 VCA and VCF

They probably loved to experiment. Same S&K filter topology everywheree, but realized with
center-tapped Vactrol
Two BJTs
Diode Ring
LM13600
in different products.

JH.

----- Original Message ----- 
From: "Aaron Lanterman" <lanterma at ece.gatech.edu>
To: "synth diy" <synth-diy at dropmix.xs4all.nl>
Sent: Friday, April 30, 2010 9:52 AM
Subject: [sdiy] Korg MS-50 VCA and VCF


The MS-50 VCA and VCF are based on diode bridges (kind of like the Yamaha GX-1/MOTM-485 filter).

http://www.korganalogue.net/korgms/schematics/MS50-module-schematics.pdf (about four pages in)

They're fairly complicted circuits.

The thing I'm left wondering is... why go with diode bridges??? I believe the MS-50 came out after the MS-20... surely they could 
have gone with a simple OTA type design?

- Aaron
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-- 
Harry Bissell & Nora Abdullah 4eva