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

brianw brianw at audiobanshee.com
Fri Apr 7 20:24:28 CEST 2023


Speaking of control feedthrough, there was a paper written about modeling the TR-808 where it was mentioned that the "pop" or "click" from the CV was beneficial for percussive sounds. That wouldn't be so good for synth pads!

Brian


On Apr 7, 2023, at 4:51 AM, 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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