[sdiy] Prophet 10 equalizer circuit

[Dave Manley]

The Prophet-10 equalizer uses a Baxandall type circuit. It looked vaguely
familar and I found the following in the 1976 National Audio Handbook:

http://www.flickr.com/photos/40138858@N07/9414290723/ (pardon cell phone pic)

The circuit has been adapted, the pots replaced with a discrete 'digital
pot' made out of 4016 switches and resistors.  Some of the values are
identical.  So perhaps the Sequential Circuit designers used it as a
reference.

-Dave

Baxandall's original paper:

http://home.comcast.net/~stphkeri/NegativeFeedbackTone.pdf

which was linked from here:  http://en.wikipedia.org/wiki/Peter_Baxandall