Doepfer

> So have 2 A-196 PLLs that i've been fooling around with -Raul's
> World of Synths latest video on the A196 pushed me to play with
> them today. I never bothered to ever compare them. Each one's
> oscillator is tuned differently. I can't get them to match. One
> is lower than the other. With each's controls identical, they
> sound different. Is this normal? It can't be. There must me some
> sort of calibration or trimpot inside. What do you think about
> this and how can I get them to be tuned identically?  Thanks
> -MAtt

There are three different versions of the A-196 module available. The main
difference was between version 1 and version 2 (manufactured from about end
of 2005): the lowpass output of version 1 was not buffered (direct output of
the PLL circuit 74HC4046), from version 2 the output was buffered by an
operational amplifier. Because of the different loads the modules behave a
bit different. The printing on the pc board tells you the version (without
"version ..." it's version 1).

But differences due to tolerances of the electronic parts may also explain
that (provided that both are the same version). Especially the specs of the
main circuit (74HC4046) may differ for different manufacturers (or even
different batches from the same manufacturer) of this circuit. Because the
PLL module is not a precision module like a VCO there are no trimming
potentiometers available to balance such tolerances. Please take a look at
the two modules. I assume that the 74HC4046 are from different
manufacturers.

Best wishes
Dieter Doepfer