Thank's for the reply.I have contacted cj and pre has been looked at by a qualified tube tech.Noise is tube related but cause of problem cannot be found.Tube plate voltage 150 volt + range recommended,4 x measured tubes 163/159/160/156 volts.Cathodes are 5.43 volts.I would send it to cj but as I live in New Zealand this would be a problem.
Conrad Johnson Classic noisy channel.
I have owned this from new and upgraded it to se.Before and after the mod,the left channel tube rush becomes noisy after 3 months use.I am a moderate user,approx 3-4 hours use per day and do not leave the pre on when not in use.I have used 3 sets of mullard m8080/cv4058 tubes with the same result.Swapping tubes from left to right,noise swaps to right channel.Have had pre checked and all tube voltages are within spec.Are there any other classic users with this problem.Dave.