Here is a picture of an older Cambridge vario:

http://www.freeimagehosting.net/3ef6ac73c2.jpg

The control on the left has two pots and a 3-position switch. The pots seem
to control audio volume and sensitivity, but I'm not sure about that. The
switch seems to control response, but I am also not sure about that.

Can anyone shed some light on this?

Thanks.
BDS