How to Choose the Best Alternate Tuning

Question

This is essentially a generalized version of this question for fingerstyle guitar, and I'm surprised I can't find it on this website: how do I find the most optimal alternate tuning for a guitar/bass(/banjo/ukulele/mandolin)/etc. piece?

There's got to be a way, I believe: for example, Jonny Atma is convinced that "You Will Know Our Names" from Xenoblade Chronicles is written in Drop D#, at least according to his page on his remix of that boss theme. Especially since Drop D# is such a rare tuning that he didn't want to retune any of his guitars to that tuning, he's got to have reached that conclusion about the optimal tuning for good reason.

Answer 1

It is my experience that each individual guitar player has their own preference when it comes to alternate tunings. That leads me to believe that the selection process used by most is a trial and error process used to eliminate alternate tunings that are uncomfortable for the performer to play, or maybe the fingering patterns are a little more confusing for the player so they avoid certain tunings. I would expect the style of playing would also be a factor to consider, whether it be blues, finger-style, slide etc. As best I can tell, the magic bullet you seem to be looking for is different for each individual and requires study and experimentation in order to discover its existence. I'm open to being proven wrong1

Answer 2

The main purpose of alternative tunings on guitar is to allow for unusual chord voicings, especially to have a particular “mood sound” from the open strings alone. This applies also somewhat to other instruments, in particular scordatura on cello or violin, but doesn't really make much sense for bass because open strings are so low-pitched that using them for any chords gives little more but musically useless sub-rumble. Bass is usually played mostly monophonically, and for that switching between tunings accomplishes little but messes with muscle/scale memory. The only alternative tuning that's really common is drop-D, and basically its only purpose is to extend the bottom range on a 4-string bass. Same with drop-E♭: you'd use it if a piece benefits from having a low E♭ but you want to change as little as possible about the instrument or effects.

That said, for virtuoso bassists alternative tunings do become interesting: some use chords on unfretted strings a lot, but not so much on open strings as flageolett harmonics. There's a lot of interesting options here, in fact far too many to fit them in an SO post. There's a lot you could just try and experiment, which is probably how most guitarists go about this as well. For example, the one piece I wrote for scordatura guitar is heavily based around the mysterious-misty sound of the _sus4^♭6₉ chord, in this case D-G-♭B-E. It's used mostly in harmonics, which is what you'd probably also do on bass.

Answer 3

I think it's worth mentioning here that a major reason that guitarists and other stringed instruments use an alternate tuning is to accommodate a singer's voice. Though I believe you are referring specifically to instrumental music given your example, this fact also supports the case that D# tuning (usually called Eb tuning) is not that rare at all, at least in pop-music. It's fairly common knowledge that artists like Jimi Hendrix, Black Sabbath, and Led Zeppelin used Eb tuning.

As previously stated, it is common to use an alternate guitar tuning to create a heavier/darker mood and/or increase the ability to bend the strings (by tuning lower than standard.) However, I have also heard the virtuoso instrumentalists, like Steve Vai and Joe Satriani, sometimes tune to a semitone higher or lower for the explicit purpose of making their riffs and licks more difficult to understand and replicate.

And considering that the determining the "best" of anything is highly subjective in nature, I'd have to agree with the other answers in that it is all about what you want to get out of the music. Using an alternate tuning exposes you to a different spread of sound which could potentially even contribute to inspiring a new song or three...

To expound on leftaroundabout's answer, another alternate bass tuning, for 5 and 6 string basses, is to drop to Bb on the low string; essentially used for the same reasons as dropping down to Eb. In my own experience, this can come in handy when accompanying and/or replicating an 808 in hip-hop or reggae. But, dropping the low B any more than that tends to make the sound way too muddy.

EDIT

See this question and this question for similar inquiries and responses...