Jazz was originally an ensemble music, largely rehearsed and played from memory, rather than improvised. Louis Armstrong began his career playing trumpet (or cornet) lead in a classic New Orleans ensemble. By the mid '20s, however, popular taste was swinging towards bigger dance bands of about ten pieces playing from written arrangements. By 1930, Armstrong was famous among jazz musicians and fans; his management, looking to increase his audience, began putting him in front of big dance orchestras, playing and singing popular songs of the time. These orchestras were often cooked up quickly for tours or recordings, and were usually under-rehearsed. It was expected for Armstrong to carry the load, which was considerable: he would usually lead the ensemble on first and last choruses, sing the tune, and then play a bravura solo. It was too much; within a few years, his lip was seriously damaged. At the time, many jazz fans believed these dance band records were a letdown from the masterful Hot Five and Seven series; later, critical opinion has rated them higher. Although none reach the heights of the greatest of the Hot Fives, many come very close.
In the first volume, Armstrong was given some first-quality material to work with, including classics like "Body and Soul" and his theme, "When It's Sleepy Time Down South." However, perhaps his best solo is on the otherwise undistinguished "Sweethearts on Parade," in which he alternates quiet phrases with rapid, chattering ones, indicative of Armstrong's sense of structure.
The second disc includes a number of superb solos on classic tunes like "Georgia on my Mind" and "Between the Devil and the Deep Blue Sea." The standout is "Star Dust." Armstrong made three cuts of the tune, which show how he developed a solo over time; unfortunately, only one cut is included here, but it's outstanding.