Designers -who's been around the longest ?

Nelson is essentially a one trick pony, Frank van Alstine never reached the same legendary status. Bob Carver is extremely capable. I have not heard one of his tube amps but I did once own a Fuzz Linear 700 which was a very good sounding amp in it's day and very affordable.
John Curl can design anything, from sound boards to phono stages, Concert sound systems to preamps. He has been involved with the design of some of the most highly regarded high end equipment and he is not finished yet. If John Curl's name is on it, you can bet on it being a great peace of equipment.  

Nelson a one trick pony? What a silly thing to say; he's only the most versatile amplifier designer in the history of hi-fi! He makes amplifiers employing dozens of different circuits, of all types and topologies.

As for Frank, the topic of this thread is who's been around the longest, not achieved the most legendary status.

Jim Fosgate, definitely not a one trick pony 🤔