Bach trumpets are available with a lot of different mouthpipes. The purpose of this article is to explain the differences between the different C trumpet pipes and suggest appropriate uses for each model.
Bach mouthpipes are made in five different tapers, designated 6, 7, 25, 43, and 44. These numbers are arbitrary numbers for the mandrels that give the pipes their inner dimensions—they have nothing to do with the actual measurements of the pipes. Models 6 and 7 are pipes originally designed by Vincent Bach and used on the early New York instruments. Model 44 is a copy of a pre-war Paris Selmer pipe. It’s made of nickel silver and has a tight taper and a bright sound. Models 25 and 43 are newer designs and are almost always the pipes used on C trumpets. 25 pipes are by far the most common, so let’s focus on them.
The most important thing to understand about Bach C trumpet mouthpipes is that they are made from the same tubes as Bb pipes are. The differences are found in the length, the venturi, and the fitting of the large end. If the pipe on a C trumpet has no markings on the receiver it’s a 25C. This is a standard Bb pipe that has been shortened from 9.750″ to 7.125″. The venturi is a stock .347″ and the large end of the tube is flared out to meet the inside of the outer tuning slide tube. The standard pipe plays with some resistance and moderate centering.
When the Bach mouthpipe is shortened by over 2 and a half inches to fit a C trumpet intonation unavoidably suffers. Bach has addressed this issue with some longer mouthpipes. The model 25A mouthpipe is 8.625″ inches in length, 1.5 inches longer than a 25H. One inch of this extra length extends up inside the outer tuning slide tube. The other .500″ is added at the mouthpiece receiver end (by moving the whole pipe back toward the mouthpiece). This extra length needs to be compensated for by pushing the tuning slide in a quarter inch. The reduced tuning latitude can cause a problem playing with an ensemble that plays on the sharp side or if a Bb tuning slide is used. The sound is tighter than that of an H pipe and the pitch is better and more stable. The 25A pipe is a very good all-around choice for players looking for a tractable instrument with a good feel.
If you would expect chopping off the end of the mouthpipe to cause intonation to suffer it stands to reason that a longer mouthpipe will improve the pitch. Bach attempts to address this with two variations on the 25 pipe: 25S (Schlueter) and 25R (reversed). The 25S pipe is a full-length Bb mouthpipe (with a .351″ venturi) mounted on a C trumpet. The full-length pipe provides intonation comparable to that of a Bb trumpet but the very short (.750″) tuning slide provides almost no tuning latitude. The “R” model reverses the main tuning slide so that the end of the mouthpipe becomes the inner tuning slide tube. The outer slide tube is attached to the slide bow, resulting in a normal length tuning slide. This arrangement also involves moving the front bell brace closer to the valve cluster. This allows the bell to vibrate more freely, creating a broader sound and generally feeling more like a Bb trumpet. While the pitch of the full-length pipes is generally better overall, the top C does tend to be flat. This can be corrected with a mouthpiece specially modified for the instrument and the resulting system can be a very good combination.
All these variations are also available using the 43 mouthpipe as a base. In fact, all other things equal, the 43 pipe has slightly better pitch than the 25, but its larger volume can make it too tiring to play on a C trumpet. We prefer the 25H pipe for older and stronger players who want the maximum of control and who are willing to work for it. A length pipes have slightly better pitch and give players more feedback. They are a better choice for younger players and for those who play a lot of Bb trumpet.