When I started on tuba in middle school (after first starting on percussion and trombone) we had 2 sousaphones and 2 tubas: an old half-lacquered-half-tarnished Conn 20K, an old mostly-raw-brass Continental Colonial, an old 1/2 or small 3/4 Yamaha top action tuba with the bottom bow smushed flat and a top action King 1140 in decent shape. All horns were in BBb and 3 valves. The Continental Colonial souzy was the favorite with the small King and Yamaha tied for 3rd. I was always careful with the horns but some of the other tuba players managed to crease and bend back the rim edge of the bell on the King by putting it on the floor too hard. I took the King home and more or less smacked the bell into shape by hitting the inside of the bell with the handle of a hammer.J.c. Sherman wrote:
Lastly, if you've played those two Kings pictured, I think the front valve instrument is so bad as to be nearly unplayable and sounds terrible. The other is... more playable but still sounds awful IMHO.
The little King isn't the greatest horn, but certainly small, light, playable and easy to get a "good" sound by most middle schoolers. I'd say it's almost perfect for middle school for those reasons. The nicer 4-valvers should wait until high school or later...

