Single trombone trigger
Some trombones have a trigger or “F” attachment. When you press the trombone trigger, it makes the instrument longer by 5 semitones (equivalent to 6th position). The instrument will produce a low F in the 1st position instead of a Bb when you press the trigger (or valve). Therefore the trigger is often referred to as an “F attachment”.
|The trombone trigger is equivalent to a 4th valve on a valed instrument|
The trigger provides further options when playing notes in 6th or 7th position. The trigger make the trombone much longer when used in combination with the slide by adding another 6 positions in length to the 7 positions on the slide. The player uses the trigger to continue playing all the way down to a low C (just above pedal Bb) from a low E in 7th position. With only 1 trigger, the instrument still can’t be made long enough to reach a low B natural.
Double trombone trigger
The 2nd trombone trigger on some bass trombones opens several more semitones of tubing. By combining two triggers with the slide, the trombone can be made much longer than usual; allowing it to play much lower notes, including the low B natural.
Length of positions
When you press a trombone trigger, you are lengthening the whole instrument. The length of the instrument determines how long each position should be to reach the next semi-tone. When you press a trigger, you make the slide positions become so long, that the slide is only long enough to cater for 6 positions, instead of the usual 7 positions.
To find the new longer positions when the trigger is pressed, do the following;
- Play F in 1st position, press the trigger and tune the trigger to sound the same.
- Play E in 2nd position, press the trigger and find the same note using a long 2nd position. Use the trigger and this long 2nd position to play the E an octave lower.
- Play Eb in 3rd, then find the longer 3rd by pressing the trigger, and so on until you get to C.
Find the (even longer) positions using a double trigger using the same method.
|Why does the slide only have 6 positions when the trombone trigger is pressed?|
To lower a note by 1 semitone, the overall length of the trombone needs to increase by 6%.
As the instrument becomes longer, the additional tubing needed to produce 6% becomes longer.
When the first 6 positions are played using a trigger, each slide position need to be further apart than usual to change the pitch by a semitone. The slide is then only long enough to accommodate 6 positions.