Valve Conversion

[The Big Ben]

Me? I'd keep looking for a valveset for the tuba and leave the Jumbo alone.

[Art Hovey]

It won't change the sound of the instrument, but it will have some effect on the intonation. While in high school and college I had an old King with a fixed recording bell and three front pistons. It had great response, but a very sharp high F in the staff. It also had its main tuning slide in the leadpipe, before the valves.
The newer Kings (after WWII) are made with mostly the same parts but have the tuning slide after the valves. They have much better intonation.

[TUbajohn20J]

kinda thought that most "King" sousaphones..featured before-the-valves tuning slides, whereas "Cleveland" (same factory) sousaphones were configured more like Conn sousaphones - with the tuning slide after the valves.

Yes. My school had a section of king sousas, one 32K, and a Cleveland. The Cleveland had the big tuning slide after the valves like the Conn.

As far as tuning slide locations, I've never noticed much of a difference in intonation. The kings had pretty good intonation. My 10J has the tuning slide in the leadpipe before the valves and it has great intonation. My other Conn's tuning slides are after the valves, and the intonation is a bit iffy sometimes on those. Some better than others. I think this idea could work. But if it were me, I wouldn't want to start cutting things. Just find another valve section.

[Uncle Markie]

I had a 1920 King 1240 the factory reconfigured from before to after the valve set and it played very well in-tune. I could stop a Strobotuner wheel dead with it. Unfortunately it finally started to rot from inside, and I had to let it go. The factory used the tight bend third valve slide bow for a tuning slide and it was not conical. Played great anyway. PM me for a photo if you wish.

Mark Heter

[J.c. Sherman]

Me? I'd keep looking for a valveset for the tuba and leave the Jumbo alone.

Seconded.

[iiipopes]

Me? I'd keep looking for a valveset for the tuba and leave the Jumbo alone.

Seconded.

Concur. Move the question - all in favor say "Aye!"