The attached picture from the Yamaha synth parameter manual was of enormous help in understanding that feature. In my case the keyboard drawn below was an eye opener. I found the XW manual keyfollow graph confusing because under the horizontal axis, they write Key Follow Base as though the variations on that axis was key follow bases. That axis rather represents keys movements closer or farther from the key follow base.
For XW-G1 (or series),
B is the key follow (KF) base
E the KF value set to 64
D is either the volume (AMP), the cut-off freq (FILTER) or the pitch (OSC)
Just analyzing the attached graph provides the following:
The more we head toward C (higher notes) the more the effect (D) is accentuated. Same effect occurs when we play the same key increasing the KF value (E goes toward F).
When KF value = 0, there is no effect except that when D is the pitch (set in OSC section), all the keys sound at the same pitch. Interestingly, when D is the pitch, KF values different from 64 results in a totally out of tune keyboard! What is the use then ?
When the KF value is negative and D is the
AMP, the closer to C, the weaker the volume
FILTER the closer to C, the louder the sound
PITCH, the keyboard is totally reversed and the closer to C, the lower the pich and the closer to A the higher the pitch. When KF=-64, the major scale from C4 is interesting
I thought I would share my understanding of this feature to help newbies like me or to be corrected if need be.
Thanks