Date: 1938. (Drawing)
What Pan American said in 1938:
This sousaphone features a deep, full and resonant tone due to its large bore, and is the most powerful model. Careful design, perfect proportions make it easy to "fill" and to carry. The scale is clear, true and unfaltering and the valve action is smooth, light and easy. Ruggedly built in BBb, is 52" in height, has a 24" detachable bell and weighs only 26 pounds. Both mouthpipe and bell are adjustable. Made of finest materials throughout and is carefully finished. Carries a full factory guarantee. made in choice of three beautiful finishes.