A 7 for Blues Bass

A 7 spells A – C# – E – G. In a blues a chord is seldom a passing event — it tends to hold for a bar or longer, and the line sung or played over it leans on blue notes that rub against it on purpose.

The bass carries a repeating figure under every bar that moves with each change of chord and tells the rest of the band the change has arrived. It seldom sounds the whole chord: it picks which tones to step through and in what order, and the band hears the harmony from whatever note it lands on at the top of the bar.

Drawn for EADG across 4 strings: the open grips lead, the movable ones follow up the neck, and a play button under each lets you check it by ear.