AW: CEM3340 stability

Haible Juergen Juergen.Haible at
Wed Mar 26 11:01:00 CET 1997

> >However, I am not so fond of the on-chip multiplier in the 3340. For
> >some reason, many 3340's are still more temperature sensitive ...
> I've used CEM3340's in my Aemit modular and they are rock-stable.
> I have an engineering memorandum from Synton Holland that explains how to
> increase the long-term stability of the CEM3340. It's in Dutch, but here is
> what it boils down to :
> Use a negative supply of -5V on pin 3 directly, and leave out the 820 ohm
> resistor (REE in the original Curtis datasheet).
> I used a small 79L05 stabilizer to derive -5V from the -15V supply.
> In the dual VCO design for the Aemit, I took no risks and used a separate
> 79L05 for each VCO on the PCB.

Yes, it's important to use -5V on the 3340.
Even then, some chips are better then others.
Roland has used the better ones in their monosynths, and the inferior
ones in their polysynths, which had autotune.
That's what I was told, at least.


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