French horn fingerings: when to use the thumb trigger (F vs. B♭ side)
If your horn has a fourth lever for your left thumb, you're playing a double horn: two horns built into one. The thumb trigger switches between them. This guide explains the two sides, where most players switch, and how to read a double horn fingering chart. The notes are shown just as they appear in your horn music.
Want to drill them? Practice these fingerings in Brass Trainer →
Single and double horns
A single horn is built in one key, usually F. Many school horns are single F horns, and they have only three valves. A double horn adds a second, shorter set of tubing in B♭. Pressing the thumb trigger sends the air through the B♭ tubing instead of the F tubing. That's the opposite of a trombone F trigger, which adds tubing to reach lower notes.
The F side and the B♭ side
| F side | B♭ side | |
|---|---|---|
| Thumb trigger | Up | Pressed (T) |
| Tubing | Longer | Shorter |
| Best for | Low and middle notes, warm sound | Higher notes, more secure |
| Written as | 1, 1-2, open… | T1, T1-2, T open… |
High notes on the F side sit very close together, so it's easy to miss one. The shorter B♭ side spreads those notes farther apart, which makes them easier to hit. The F side has the warmer sound in the low and middle range.
Where most players switch
Most horn players use the F side up to about G on the second line and switch to the B♭ side from G♯ or A upward. Your director or teacher may set the switch point a little higher or lower, depending on your horn and your range.
Reading a double horn fingering chart
A double horn fingering chart often shows two fingerings for each note: one for the F side and one with a T for the B♭ side. Sometimes the valves stay the same and you just add the thumb: A on the second space is 1-2 on the F side and T1-2 on the B♭ side. But often the valves change too. F in the first space is 1 on the F side but T open on the B♭ side.
Because some notes change and some don't, learn each B♭-side note as its own fingering rather than as an F fingering plus the thumb.
Practice these fingerings
- Play a slow scale from middle C to the C in the third space, switching to the B♭ side at your switch point.
- Play the notes around the switch point on both sides and listen for the difference in sound.
- Keep your thumb resting on the trigger so switching is just a press, not a reach.
Then quiz yourself in Brass Trainer, which includes double horn fingerings with the thumb trigger.