Tuning Bell Conversion:
This is one of the few alterations you can make to a trumpet that produces desirable results for most players. By removing the bell and lead pipe braces, the bell becomes less restricted by weight and contact, allowing it to vibrate more freely, giving the instrument improved response, and a more “live”, resonant sound. Another major benefit of tuning with the bell is improved intonation.
When adjustments are made in the main tuning slide you pose a higher risk of causing a node to hit in an unfavorable spot of the instrument. The lead pipe and mouth piece are very critical in setting up the characteristics of the sound quality and intonation of the trumpet. Any variances in these areas greatly increases the likelihood of the instrument producing an undesirable result in some notes.
By tuning with a movable bell, that late in the sound production, you have a FAR less chance of causing a node to hit on a pipe seam, water key nipple, dent, etc, that would adversely affect the sound.In addition to the improved quality advantages, the bell is now removable which gives you the option of fitting the horn with additional bells for different playing situations; for example, you may want a copper bell for symphonic work, or a lightweight large flair bell for lead work. This makes your instrument twice as versatile for different situations and in many cases could save you thousands in having to buy an additional horn for other work. Another important point to note is about correcting existing flaws from the manufacturing process. Some manufactures (who I think most of us are aware of) don’t commit to as high a degree of quality standards as others. One common flaw a tunable bell corrects is relief of stress on the bell and lead pipe. When a bell is soldered on the horn, if the braces are not put on in a certain order or if the bell crook bend wasn’t bent perfectly, this automatically builds a LOT of stress into the horn. This is commonly noticeable through a suffocated sound, poor response or lack or projection. One of he only drawbacks to this alteration, other than just personal taste, is that it makes the instrument more vulnerable to damage due to the lack of bracing. Some players have also experienced a compromise in projection, however this can be helped or counter acted by using a movable sound post. This is a common alteration that many orchestra players have done to an Eb horn and then add a C trumpet bell (commonly a Bach 229 or 239). This is usually done in light of many directors preference for the timbre of a C trumpet in the ensemble. This gives the player the ability to have the desired sound while still maintaining the ability to be able to play in, or transpose more easily from keys which pose odd/awkward fingerings on C or Bb trumpet. Wynton Marsalis had this done to his Schilke E3L adding a Bach 229 bell. He played the Haydn using this horn on "The London Concert" album, and it can be seen on the CD cover. I have adapted several bells, including a 229, for a Blackburn Eb, for Alan Hamant of the Delaware Symphony.
Pictures of our tuning bell conversion on a Bach D/Eb