Taken from 1970s Live at Leeds, “Young Man’s Blues” is the Ox at his most ferocious, and a shining example of his lead bass concept. His bass lines, though supportive, are also melodic enough to be considered a solo on their own.
The entire tune is basically E minor, and Entwistle plays almost exclusively in the E blues scale. Through most of it he leans on that root note, but there are some places where he doesn’t play the root on the downbeat, and some where he doesn’t play the downbeat at all. Especially interesting are bars 85, 100. 111, 114, 145, 154, 166, and 169, in which he plays the fourth (A) on the strong beat, and emphasizes it so that it sounds almost like the root note. But since he is still playing E blues, it serves to make the harmony a little vague. For measure 152 he stresses the A so much that the D to E hammer sounds as much like a fifth as a root. Check out all the other times he accentuates notes other than the tonic. All this takes a modal tune and gives it a strong sense of motion, frenetic motion even.
Ox also molds this controlled chaos with what he does rhythmically. Though we hear him repeating rhythmic ideas (anyone read my bit on isorhythms?) he is also constantly changing them. Usually, he’ll repeat a rhythm, like in measures 58 and 58, or in measures 73 and 74, where he plays solely on offbeats, before moving on to another idea. A fantastic occurrence is in measures 168-174. He plays two dotted quarters and then a quarter note, dividing the measure 3-3-2, but in the next bar reverses it to 2-3-3. He repeats this motif for the next six measures, but varying the initial idea, thus giving us a similarity that produces a groove, but alterations that create motion and interest.
And he improvised all this!