Conn 20J with fourth valve like Besson/euph?

[The Big Ben]

Hi:

I sat next to a fellow at Seattle TubaChristmas who was playing a Conn 20J that had a fourth valve that stuck out the side like some Besson compensating horns or some euphoniums. The area was kind of cramped so I wasn't able to get a good look at it and the player didn't answer my question when I asked about his horn's origins.

I'm guessing that this was an add-on later because I have never seen such a configuration in any catalogs or pictures I have seen. Then again, I haven't seen but a small fraction of the reference material.

Anyone know if this could have been a factory option?

Jeff "But it had a good sound" Benedict

[TUbajohn20J]

it was definately custom