Re: changing the key
Reply #2 –
Transposing Instruments:
What are transposing instruments and why do we care?
Transposing instruments are instruments whose music is written (usually in treble clef) with respect to the native pitch of the instrument rather than concert pitch.
OK, what does that mean?
Let's take a trumpet for an example:
Now, normally a trumpet is a Bb instrument. There are exceptions which will help make things clearer later.
The reason it is called a Bb instrument is that its fundamental note, with no valves operated, is a concert Bb. From the players perspective we call this fundamental note C, even though it is still a concert Bb. Bear with me, this will make sense soon.
Trumpets normally have 3 valves. When played, the combination of which valves are pressed (operated) and the players embouchure control what pitch a note sounds.
If there are no valves operated and the player "blows" the lowest note they can (ignoring pedals which are a special case) then that note is considered, and written as, middle C on a treble staff.
Trumpets come in several pitches. You will see Bb, A, C, D and Eb most commonly though by far the most prevalent is the Bb. If a trumpet is mentioned without a key then it will be a Bb trumpet.
In ALL cases the lowest note with no valves operated is called middle C. This means that with correctly written (and transposed) music the player can pick up their trumpet and play from the music and not have to think about using different valve and embouchure combinations to play the correct pitch.
If playing written (transposed) middle C
A Bb trumpet will sound a concert pitch Bb below concert middle C
An A trumpet will sound a concert pitch A below concert middle C
A C trumpet will sound a concert pitch C (this one happens to be in concert pitch)
A D trumpet will sound a concert pitch D above concert middle C
An Eb trumpet will sound a concert pitch Eb above concert middle C
As I hope you can appreciate this makes things a lot easier for the musician if they need to move from one trumpet to another. It even helps if moving from one brass instrument to another*.
Pretty much the same thing applies to all other transposing instruments, but lets take another example: The Saxophone.
Saxophones commonly come in 4 varieties (again, there are exceptions):
Soprano (Bb)
Alto (Eb)
Tenor (Bb)
Baritone (Eb)
By having transposed music for each instrument the player can move to any of them without having to know multiple fingering in order to play the correct pitch.
In fact, without this transposition they would most likely be written in different clefs as well making moving around from instrument to instrument even harder.
Think violinist playing viola, suddenly they have to read alto clef instead of treble clef, not to mention that the strings are different pitches too. If they go to 'Cello then they need to read bass clef as well. I believe it was to overcome the difficulties this brings that the idea of transposing instruments first came about.
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In order to correctly transpose music for a transposing instrument you need to know the key of the instrument AND whether it sounds above or below the concert pitch note.
E.G. the Bb trumpet mentioned earlier sounds below the concert pitch of the written note. So, in order to get the sounding note the correct pitch the music must be written 2 semitones HIGHER than concert pitch (Bb is 2 semitones LOWER than C so the written music must compensate for this).
If the music was being written for an alto saxophone then it must be written 9 semitones higher than concert pitch because an alto saxophone playing its' C actually sounds the concert Eb BELOW C. The distance between Eb to the C above it is 9 semitones, so to sound a middle C the alto sax music must be written as a second space A (9 semitones)
For Horn in F the difference is 7 semitones, and so on for other transposing instruments. Note however that Horn is a somewhat different beast... If you are going to write for horn, talk to a horn player!
For Baritone sax, the difference is a whopping 21 semitones!
* In a British tradition brass band ALL the instruments (excluding bass trombone) are written in transposed treble clef, including tenor trombones and tuba's (usually called basses)
Soprano cornet - in Eb - is written 3 semitones down from concert pitch
Cornet and Flugel Horn - in Bb - is written 2 semitones up from concert pitch
Tenor horn (more properly it should be called an alto horn) - in Eb - is written 9 semitones up
Euphonium, Baritone and Tenor Trombone** - in Bb - is written 14 semitones up
Eb Tuba - in Eb - is written 21 semitones up
Bb Tuba - in Bb - is written 26 semitones up
** outside of British tradition brass bands Tenor trombones are normally considered a concert pitch instrument and written in bass clef. Historically they have also been written in concert pitch Tenor clef which uses the same note positions*** on the staff as transposed treble for Bb instruments but have a key signature with 2 extra flats (or 2 less sharps).
*** A tenor clef middle C is on the 4th line of the staff and is played in 3rd position on the slide. If you have a transposed treble clef part for a trombone then that concert middle C is now called a D and is still on the 4th line of the (now treble) staff and still played in 3rd position on the slide.
I hope this has been more helpful than confusing.