AW: LM13600 VCA, latest news

[jorgen.bergfors at idg.se]

Well, the PSU I'm using is based on the uA723. Actually it's the one from 
Elektor Formant. I will check the supply. Maybe the cable length from the PSU 
could be a problem too. 

/Jorgen





MIME:Juergen.Haible at nbgm.siemens.de on 98-09-04 11.31.08
To:  synth-diy at mailhost.bpa.nl @ SMTP ,  Jorgen Bergfors at IDGSE
cc:  
Subject: AW: LM13600 VCA, latest news 

 >I changed the "Serge" circuit according to JH's recommendations. 
 [...]
 >The linearity of the output is still clearly not as good as the
"normal" 
 >circuit, from the NS datasheet. 
 [...]
 >Conclusion 
 >is that the circuit from the NS datasheet really is as good as this
chip will 
 >get. 

Well, I'm almost convinced now. The designers of some chip should
know it's behaviour better than anybody else, after all ...
You really made me curious, and I think I will put a linear ramp at 
my Morphing Programmer's VCAs again, when I find the time.
One last question: Did you look at the negative supply voltage of
the Serge circuit? I mean *theoretically* there could be a source of
distortion, too. How "hard" is your power supply ?

JH.