Trombone Trigger

A trombone trigger — often called an F attachment — adds extra tubing that lengthens the instrument by about five semitones. Engage it and first position now gives you a low F instead of the usual B♭. In effect, it does for the trombone what a fourth valve does for a valved brass instrument.

Where the trigger really earns its keep is down in the lower register. It gives you more options when you’re already out in 6th or 7th position, and combined with the slide it effectively adds six new positions below the standard seven — letting you work your way down from a low E in 7th position to roughly low C, just above pedal B♭. Even with a single trigger, though, low B natural is out of reach.

That’s where a second trigger comes in. Bass trombones built with two triggers open up even more tubing, and combining both triggers with the slide finally puts low B natural within reach.

One thing to keep in mind: engaging the trigger lengthens the whole instrument, which means the spacing between slide positions changes too. To keep each semitone the correct distance apart, the six trigger positions have to be spread further apart than the seven you’re used to without it — which is exactly why the slide only has six usable positions in trigger mode instead of seven.

Here’s a practical way to find those new positions by ear: play F in 1st position, then press the trigger and tune it until it sounds the same note. Next, play E in 2nd position, press the trigger, and find the same E an octave lower using a long 2nd position. Continue the pattern — play E♭ in 3rd, then find the longer 3rd position with the trigger engaged — and keep working your way down semitone by semitone until you reach C. You can use the same method to work out the even longer positions on a double trigger.