I don't remember how to do this ...

[Chip]

I have two trombone parts written in concert key - F Maj - and just 
realized that the notes are one step too high. I don't recall how to 
transpose a part without changing the key signature. If I recall 
correctly it involved two /transposes, is that right? Can someone help 
me? Here's how I lay out my code -

% ------ Trombone 1------
tbonea = { all the notes of the piece }
trombonea = \relative c {
 \global
 \key f \major
 \set Staff.instrumentName = #"Trombone 1"
 \set Staff.shortInstrumentName = #"Tbn 1"
 \clef bass
 << \tbonea >>
}

% ------ Trombone 2------
tboneb= { all the notes of the piece }
tromboneb = \relative c {
 \global
 \key f \major
 \set Staff.instrumentName = #"Trombone 2"
 \set Staff.shortInstrumentName = #"Tbn 2"
 \clef bass
 << \tboneb >>
}

Thanks,
Chip