[sdiy] New take on VC moog ladder

[Scott Bernardi]

JFET's are much harder to match than bipolar transistors. (that's why the JFET
input opamps have looser Vos specs than similar bipolar input opamps). Matching
discrete JFET's would be darn near impossible (unless you've got a hundred or so
to work from).  And I'm not aware of any monolithic matched JFET pairs that are
available (something like the CA3046 but with JFET's).

Stefan Schneider wrote:

> >> what's a problem with the Q13?
> >
> >I just thought it was unecessary.
> >
>
> I think it'll be needeed instead... he needs to drive the current up before
> feeding it back to the ladder. And like they say "You can never have enough
> buffering" :)
>
> >> The output stage at least
> >> could be buffered? Paul's previous version of this was strange as it
> >> actually tried to use the Walt Jung design, wasn't it?
> >
> >He did cheat some, didn't he? ;O)
>
> That kind of cheating is fun :]
>
> >In the end, I don't have a hard feeling against it, I just raised a
> >few opinions on things which I perceived as odd in order to possibly
> >let Paul see some flukes, if they indeed is there.
>
> BTW, I think it'll depend a lot on the matched transistors used on the
> ladder wether or not Q13 will be necessary... I'm thinking about another
> cheat on the VC design (Please don't hit me BTW :) Moving into a JFET ladder
> for extra drive)
>
> Cheers
>
> Stefan

--
Scott Bernardi
sbernardi at attbi.com