Apple Logic Express 8 - Manual (Page 647)

Chapter 28 Creating Apple Loops 647
Apple Loops Transpose to the Wrong Octave
Transposing an Apple Loop to a higher pitch may result in the loop being played back
at a lower pitch, and vice-versa.
Example: If an Apple Loop is transposed to sound seven semitones higher, it will
actually play back five semitones lower. This is harmonically-correct transposition, but
it’s probably not to the intended octave.
Transposing audio material is a technically complicated process which always implies a
certain loss in quality. The greater the transposition range, the more significant the loss
in quality. This is why Apple Loops are always transposed by the smallest possible
value.
You should note that sound quality is dependent on the transposition amount of the
Apple Loop’s original key—not the project key, which defines the zero line of the
Transposition track. As an example; if the project key is already five semitones above
the original key of an Apple Loop, setting the transposition value to +2 will transpose
the Apple Loop downwards by ten semitones. This is because the transposition value is
only five semitones below its original key (rather than seven semitones above it).
In the classical European music system, an octave is divided into 12 semitones. As +7
semitones is harmonically equal to –5 semitones, a value of –5 is used as the
transposition amount. The same happens with other settings: A transposition value of
–9 will result in +3, and +12 will result in ± 0. The use of the nearest harmonically equal
transposition option is based on delivering the best sonic results, with smaller
transpositions being desirable.
Converting Apple Loops to Audio Files
When you convert an Apple Loop into an audio file, the resulting file may not play at
the project’s current tempo and key settings. Rather, the new audio file will play at the
original tempo and key of the Apple Loop.
This happens when you select an Apple Loop and choose Audio > Convert Regions to
New Audio Files from the local Arrange menu, and change the File Format parameter in
the ensuing window from “Original file type” to either WAVE or SDII. This creates a copy
of the original Apple Loop file, but without the transient and category tags. The lack of
these tags restricts file playback to the originally recorded tempo and key of the Apple
Loop—not the tempo and key of the project.
If you want to turn an Apple Loop into an audio file that uses the project’s tempo and
key settings, select the loop (or loops) and choose File > Export > Region as Audio File.
Be sure to select the “Add resulting files to Audio Bin” checkbox to use the new file in
your current project.