Graeme Cohen's Page

Back in 1984 Graeme J. Cohen designed a very nice low noise microphone amplifier.
It was originally published as AES Preprint 2106 "Double Balanced Microphone Amplifier" and sold as the Philips OM1556 hybrid.

This circuit has been the subject of much discussion and debate, some of it incorrect.
We have managed to coerce Graeme out of hibernation and get him to put pen to paper and make a few notes about this amplifier. (Yes, it really was "pen to paper" as he doesn't own a computer.)

Double Balanced Microphone Amplifier Notes (5.5 meg file)

Graeme's recent investigations include distortion measurement using 2 tones in a 3-4 ratio.
3-4 Ratio Distortion Measurement (800K file)

A list of papers penned by Graeme.

Graeme can be seen in person at meetings of the Adelaide chapter of the Audio Engineering Society.
He can be contacted indirectly via email at
GraemeCohen AT LeonAudio DOT com DOT au
Messages sent to this email address will be forwarded to Graeme. (remember: he doesn't own a computer)