As a corollary to this discussion that there are in fact issues with using at least certain 7308 tubes in the amp. As per Conrad Johnson, the amp was not designed to use those tubes and would cause problems. I have tried old stock Sylvania 7308s and did indeed have problems with them. Don't know the technical cause but be careful when tube swapping. The amps calls for 6922 & 6550's which I have alternated NOS tubes with success.
Conrad Johnston LP70s amp 6922 tube upgrades
Hello, I am looking for CJ LP70s owners out there that have experience with the above mentioned amp and upgrading the original 6922 tubes to say 7308's and PQ version tubes! Are there any issues with doing this as I have been told that the JAN spec tubes will not work in the amp??? But I thought the 7308 and the other JAN PQ versions etc would drop right in. Can anyone out there clarify this or tell me of there experience with doing so? many thanks D