Electric Bass: Bb 7sus4 in the Changes
Where Bb 7sus4 sits once the key is named, and what this seat is responsible for while it sounds.
Bb 7sus4 is Bb – Eb – F – Ab. Naming the notes is where a chord chart stops. A tune asks the next question instead, and that is the one this page answers.
Bb 7sus4 has no third of its own, so it names no degree until something around it does — which is why it turns up as a suspension over a chord that already has a job rather than as a chord with one.
The electric bass seat carries the amplified bottom — the same harmonic duty as the upright, played with a fingerboard that answers back and a sustain the room can hear over a backbeat. The chord tones are the same ones the upright would choose; what changes is that a note can be held through the bar instead of dying, so a line can lean on a chord rather than announce it.
Every shape is drawn for EADG across 4 strings, the open ones first and the movable ones up the neck after them, and each one plays back so you can hear the voicing before you commit it to a chorus.