[sdiy] Oberheim Xpander VCF

[Tom Wiltshire]

The real power of having 4-way mixing is being able to morph between  
filter settings. Obviously this requires a voltage controlled mixer,  
but I've long had my eye on the 4 VCAs in the SSM2164 for this  
purpose. It'd be almost a one-chip solution (the VCAs need a current- 
voltage convertor op-amp stage after them), and scarely any more  
complicated than the Xpander's design with many resistors and the  
analogue switches.

T.



On 15 Jan 2009, at 15:26, David Moylan wrote:

> This type of versatility is available to cascaded integrator  
> filters in general, by mixing outputs of the separate stages.  Marc  
> Bareille created an add on for the MOTM-440
>
> http://m.bareille.free.fr/modular1/vcf_multimode/extrapole.htm
>
> Although it's nice to be able to switch in discrete steps you can  
> probably have some fun with a 4 way mixer as well.
>
> Dave