Galt is G, B, F, A# and Eb — with every tension it can carry altered at once.
It sounds maximum tension, barely holding together. Not one chord but an instruction: take the root, third and flat seventh, add any two alterations, and let the rest go.
Altered dominant — the hardest pull available.
Also written G7alt, G7altered or G altered dominant.
An open string adds a note without a finger: a tension on top or a pedal below. These belong to their key and cannot be moved up the neck.
Alt is not one chord but an instruction: a dominant with its ninth and fifth altered. Its usual home is between Dm7b5 and Cm6, where the ♭13 is already the minor third of the chord it resolves to.
Listen for: The ii’s minor third falls a whole step to the V’s ♭13, which holds as the minor third of the i.
In a major key Galt works as the V of the ii: Bbmaj7, Galt, Cm7, F7. Its ♭13 is the minor third of the ii it leads to.
Listen for: The top voice rises a half step to the ♭13 and then stays put: minor third of the ii, flat seventh of the V.
Every note of Galt is in G altered.
Each of those is a page: the scale across the neck, and the chords it harmonises into — which is where Galt sits in it. Every scale.
Change one note of Galt and you have (drop the sharp ninth), (the sharp ninth becomes the ninth) or (the flat thirteenth becomes the fifth).
Galt is an altered chord — a dominant seventh with its fifth or ninth moved. Altered dominant chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.