Originally Posted by
paulmaybery
If this is a Conn, yes from the Bb (in the staff) downward is usually pretty flat. Other quirks include the 1st valve that is either very sharp or very flat on various harmonics. If it is a double bell, things can be worse.
If you are sensitive to your embouchure and pitch, you may realize that on those very flat notes, there is a figure 8 effect.
(Hard to explain) That is, there are often two centers to the pitch. The obvious one is the 'flat' one as it usually responds with the most resonance and ease. But, if you can manage it, there is often a second center to the pitch that is higher (hence the image of the 8). If your chops are strong enough, you can put the sound there, hold it and consequently play the scale in tune.
For the past 30 some years, I have conducted a band (The Yankee Brass Band) in New England, that plays on all mid-19th century brass instruments. It is pretty much a given that the 2nd harmonic (Bb) will be flat. (That is Eb on an Eb instrument)
I'm not sure why that its, but it seems to be an inherent problem in some designs of conical instruments. Today with our wonderful modern instruments, this is not an issue.
From an historical perspective, many of the brass instruments in the early 20th century originated from 19th century models.
For an example: Conn bought out the Isaac Fiske factory in Worcester, MA in the 1870s. As he produced his own line of Conn "Wonder" instruments, he used many of the bell mandrills he acquired from Fiske. In fact, we can trace a modern Schilke Eb Cornet, to a 1880s Conn Wonder Cornet, to a 1860s Fiske Eb Cornet. The bells are almost identical. Modern engineering has found ways to improve intonation. We've been learning these days that lead pipes have a huge effect on how a horn plays.
It is very imaginable that by the 1950s, many of the bugs were still not worked out. Through the advantage of computer engineering and virtual acoustics, manufacturers have learned how to deal with many of those issues which usually involve the profile or taper of the bugle. In the old days it was 'trial and error' and once the tooling was made, it was expensive to retrofit the machinery. Generations of instruments would be made, passing the quirks down the line, year after year.
Today, the models that we use and have evolved are relatively successful from an accoustic/intonation point of reference.