When tuning the guitar to something other than standard tuning, often its treated as a transposing instrument. This has come up before on the forum, but I have put together a few examples from published guitar tab books. Every published tab book I have look through treats detuned guitars as transposing instruments.
The examples show two scenarios where each string is detuned equally from standard tuning. In both cases, the notation and tab looks like the guitar is tuned to E standard. The guitar tuned to E♭ standard becomes a B instrument, sounding a minor 9th below the written pitch, and the guitar tuned to C♯ standard becomes an A instrument, sounding a minor 10th below the written pitch.
It becomes more complicated when dealing with drop tunings. The first example in drop D, everything, including the detuned 6th string, is notated at pitch (with the regular octave transposition of the guitar). In the second example, tuned to drop C, the notation looks like the previous example in drop D.
The decision as to which strings should transpose and which should becomes harder to make when half the strings are detuned and half are not.
The most flexible solution would be to provide the option for the user to specify the written and sounding pitch for each string individually.
The E♭ standard example would be:
String 1—written E5—sounding E♭4
String 2—written B4—sounding B♭3
String 3—written G4—sounding G♭3
String 4—written D4—sounding D♭3
String 5—written A3—sounding A♭2
String 6—written E3—sounding E♭2
while the drop C example would be
String 1—written E5—sounding D4
String 2—written B4—sounding A3
String 3—written G4—sounding F3
String 4—written D4—sounding C3
String 5—written A3—sounding G2
String 6—written D3—sounding C2
The above would only apply to when the layout is set to transposing. When set to concert pitch, the guitar should transpose exactly as it currently does, i.e. sounding an octave below written.
I do know about the workaround by transposing the pitch directly in the VST in play mode, but that doesn’t allow the same functionality as proper transposing instruments. The user should be able to switch between transposing and concert pitch and have the notation adjust, as it does for the transposing wind and brass instruments.
Guitar is the most common instrument to make extensive use of alternate tunings, but this functionality would ideally be extended to all stringed instruments, including the violin family and other fretted instruments. This also has overlap with notating the guitar with a capo, which transposes the guitar in the other direction.
Due to how common this notation is for guitar, I hope this functionality will be added to Dorico when the team has time to dedicate to it.
