Martin had a couple models during the mid-1920s, and up through (I believe ...?) the mid-1930s ... those being the one you have, and another, designated "New Symphony". I believe the "New Master" different from the "New Symphony" in the material used in the bell-section; namely, silver.
(BTW -- Please check the bell for an engraved hallmark, designating the presence of "Sterling Silver", rather than silver-plating).
I had an opportunity (missed, sadly) to acquire a fine "New Symphony" with exquisite engraving. I have been curious if Martin constructed these models with conical (step-bored) tubing sections. The Dansant does not ... it uses cylindrical tubing (but, shared valve-section) ... hence, a rather "life-less" tonal quality. The conical sectioned horns (including the "Imperial") tend to produce a richer tonal palette, with even-tempered overtones.
BTW #2 -- I have tried to contact the author / website manager at
dallasmusic.org/index ... to correct several glaring errors in the "information" (??) provided, regarding Martin horns. No response. Be careful ... as the saying goes: "don't believe all that you read".
~ Namaste ....
Yogi Robt