C-J 2300A bias specification

Hi All,

I am having my 2300A amp re-capped by my local, highly experienced electronics repair shop and the tech there said he contacted Conrad-Johnson and was told that the bias setting was "propietery information." So, does any one out in A-gon land know for sure what actual voltage value the bias should be set to?
I am completely ignorant regarding these issues so please forgive me if I am asking the question in an odd way. My tech said the answer would be a voltage number.
Thanks!