[sdiy] what opamp for "warmth"? (I know, I know...)

Andrey Salomatin filipovskii.off at gmail.com
Fri Apr 7 14:34:37 CEST 2023


Curious, how was the second transistor hooked up?

> The later MS20 had a second transistor, which makes things more linear/symmetrical and you can run larger amplitudes -> less noise. 

Andrey

> On 7. Apr 2023, at 13:51, René Schmitz <synth at schmitzbits.de> wrote:
> 
> You'll find the same VCA in the 909 in a few places. (Bassdrum , Toms, Clap..)
> 
> Note how far the signal is divided down. 
> 
> It's noisy, and nonlinear, and has some control feedthrough. Show what you can get away with for a single monophonic signal. 
> 
> The MS10 had the single transistor, the early "Korg35" MS20 had the same. 
> The later MS20 had a second transistor, which makes things more linear/symmetrical and you can run larger amplitudes -> less noise. 
> 
> According to the schematics the transistors shall be selected. jx3p also says "SEL". 
> 
> Anyone would know what for? Equal gain? 
> 
> 
> Best,
>  René
> 
> On 07.04.2023 11:04, Adam (synthDIY) wrote:
>> 
>> David G Dixon via Synth-diy pisze:
>>>>>> Whatever the VCA is in the Korg MS-20 really warms up the sound of that synthesizer.  You can find the schematic on the internet.  I have something redrawn by a fellow named Marjan Urekar that I looked at years ago.  It involves two transistors.  It is evidently also the VCA used in the Roland JX-3P.
>> 
>> 
>> Interesting.... here's the JX3P version
>> 
>> <grab 2023-04-07 at 6.57.54 pm.png>
> 
> 
> 
> 
>> 
>> 
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