[sdiy] Oberheim SEM module

[Magnus Danielson]

From: "Cornutt, David K" <david.k.cornutt at boeing.com>
Subject: RE: [sdiy] Oberheim SEM module
Date: Tue, 6 Apr 2004 13:31:55 -0500
Message-ID: <F2907359F3D3E246843DDCA786665653025E6F68 at xch-se-01.se.nos.boeing.com>


Hi David,

> From: Magnus Danielson [mailto:cfmd at bredband.net]
> >> Not quite, the TL081 and TL082 has JFET input diffrential 
> > pair rather than JFET
> > buffered NPN diffrential pair. From a functional point of 
> > view (high-Z input)
> > it's about the same, but the distorsion characteristics are 
> > not the same. 
> 
> Apolgies in advance, Magnus, but this confused me.
> Are you saying that the 741's inputs are JFET buffered?
> I always thought that the 741 is all bipolar (and doesn't
> have particularly good input impedence characteristics
> compared to more modern opamps).

David, I'm talking about the SEM VCOs and VCF, so look in the schematic and
you see that JFETs is being used as buffers. In some other designs (Buchla VCO
for instance), they used JFET buffers before hitting on the bipolar 741.
Sorry for confusing you! I was a bit unclear there...

Cheers,
Magnus