Detachable bells have made the study of these variables considerably easier. A flare that is too hard will have an thin, harsh sound. A flare that is too soft will have a dead sound. A softer flare will be darker sounding and slower in response. A harder flare will be brighter sounding and quicker in response.
Older horns tend to have very thin flares due in part to many years of wear.
Flares are sometimes constructed with a garland about one inch wide added at the rim of the flare. A garland will make the horn somewhat darker with better projection. Combinations of all these factors make for many different possible bell flares. These factors generally hold true for the temper and thickness of the metal used in the body of the horn as well. Copyright John Q. Ericson.