Kudos to James Grant for finding the audio of a 1975 lecture at Westminster Seminary by the late Dutch New Testament scholar Herman Ridderbos on the "Christology of John's Gospel."  Pretty fascinating.  I was first exposed to the writings of Ridderbos in a doctoral seminar at the Beeson Divinity School.  I found his work quite challenging but very rewarding.  And while I'm certainly not as familiar with Ridderbos' thought as my friend James Grant is, I think I can safely say that you'll find his writings and words to be consistently thought-provoking and informative.