--- Dieter Doepfer < hardware@... > wrote:

> From: "Dieter Doepfer" < hardware@... >
> To: "Bakis Sirros" < synth_freak_2000@... >
> Subject: AW: 1 Re: Noisy A-131 VCA >>
> opamps
> Date: Mon, 9 Feb 2004 14:33:56 +0100
>
> Please forward ...
>
> > Hi folks,
> > my A-131 exponential VCA was bought in September
> 1998 (no idea when it
> > was built. PCB says it�s a version 2 from 1996).
> > It also uses the PA382. (the other two ICs are
> Texas Instruments� TL062)
> >
> > Look on the PCB (frontplate facing to the left):
> > -below the PA382 you can read: LIN:3381 LOG:3382
> > The module overview of my owner�s manual (NOT the
> service manual) says
> > "...built with CEM3381 / 3382"
> > So is the PA382 the same chip as the CEM3382 but
> with another name Or
> > is it a totally different IC Dieter, please help!
>
> CEM3381 = PA381 (dual linear VCA)
> CEM3382 = PA382 (dual exponential VCA)
>
> The succeeding company of "Curtis Electromusic
> Specialties" (CES) that
> manufactured the original CEM chip was "OnChip" and
> changed the names of the
> VCA circuits as specified above.
>
> > another look on the PCB:
> > -above the PA382 I can find a blank field marked
> "ST2" with ten solder
> > points (actually that�s two pairs of five solder
> points marked: + /
> > ground symbol / triangle symbol / CV / - )
> > -to the lower right of the PA382 there�s a solder
> point marked "JOUT /
> > BOARD 2" .
>
> As Florian already mentioned is was possible to use
> the second VCA of
> CEM3381/82 (resp. PA381/82) in combination with a
> second A-130/131 module.
> For this the pc board of the second module was
> completely assembled with
> exception of the VCA circuit. For the connection
> between the two modules a
> 10 pin connectors was used.
> But we never published this technical detail. Only
> some owners of the A-100
> service manual discovered it. The advantage by using
> the second VCA in the
> CEM chip in combination with a second module without
> VCA chip was not too
> much. But now, as the CEMs are no longer available
> it might make sense to
> activate the second VCA in the old versions of
> A-130/131. But for this we
> would have to manufacture the old versions of the
> modules resp. pc boards
> again. At the moment we have no old pcb's in stock.
>
> Best wishes
> Dieter Doepfer
>
>
>
> > Florian, you said that you can modify the
> A-130/131 into two VCAs when
> > they use CEM chips. Is it then possible with my
> VCA with these solder
> > points
> >
> > bye, Paul
> >
> >
> > Julian wrote:
> >
> > > >>The new 130/131 uses CA3080 OTAs (like the 132
> always did).
> > >
> > >
> > > Dont the 130/131s use the PA382 Mine do, but i
> dont know what
> > date they
> > > were made.
> >
> >
> > > [...]
> > >
> > > Theres a lot of opamps out there. The ICs on
> the 130/131s are certainly
> > > socketed (the 132 is soldered in).
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> > Doepfer_a100-unsubscribe@yahoogroups.com
> >
> >
> >
> >
>
>

=====
Bakis Siros
Parallel Worlds / Polariton
Athens-Greece
1 group owner
http://www.rubber.gr
http://www.shimarecords.co.uk
http://www.ward12.com

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