[sdiy] Oberheim SEM module

[jbv]

> I'd suggest that your friend look at the OB-X voice card schematics to see
> what came after the SEM. It's "the same but different," as some people
> say -- the next version of the same basic circuits. For example, the SEM
> uses 741 op amps paired with FETs whereas the OB-X uses TL081s or TL082s
> (which have built-in FET buffers, if I've got my facts straight).
>
> The OB-X has CA3080s all over the place to provide for programmability, but
> they also present additional VC possibilities. These 3080s are used like
> voltage controlled resistors.
>
> The OB-X uses Curtis CEM3310 envelope generator chips for the ADSRs.
>
> 24dB filters didn't appear on Oberheims until the OB-Xa or OB-8, which used
> Curtis VCF chips.
> --
> john

Mmmh... that's interesting, but one of the goals was to keep
the whole price low, which means avoiding Curtis chips...

BTW, is there any online version of the OBX schematics ?
A google search didn't find much...

JB