An earlier drum machine, the Chamberlin Rhythmate, contained drum samples recorded on a tape loop. The Rhythmate was capable of 14 drum patterns, but changing the tempo also changed the pitch of the drum tones. (This technology was later adapted for use in the Mellotron.) These limitations were addressed in Wurlitzer’s advertisement:

You can set [the Side Man] to any rhythm pattern you want. […] Changing the speed does not change the sound or alter the pattern—at it plays for any length of time you desire.

The Rhythmate was produced by a man named Harry Chamberlin, who reportedly built them in his garage. On the other hand, Wurlitzer was able to reuse parts and technology from their existing product lines. The drawing 61114 below depicts a pulley used to rotate the turntables in the model 1700, 1800 and 2700 jukeboxes. According to the drawing, this part was also used in the Sideman, presumably to rotate the commutator.

However, Wurlitzer consistently aimed to produce user-friendly, beginner-friendly instruments, and from that perspective the Side Man itself also had limitations. It cost $395 (around $4500 in 2026 dollars), and, although Wurlitzer claimed that it was “completely portable”, it came in a 26 × 25 × 11 1/2” finely veneered cabinet that was nearly as heavy as Wurlitzer’s smaller organs.

In 1967, Wurlitzer was granted patent 3,317,649, which described an organ containing a percussion unit. Explaining the novelty of the invention, the patent references the Sideman:

Although the “Sideman” rhythm device produces excellent results and is extremely versatile, it does entail the use of an additional piece of equipment which in some instances may be undesirable. It also requires the organist to conform his timing to that of the rhythm device. Accordingly, it is the primary object of the present invention to provide an electronic organ with built-in rhythm accompaniment.

As Wurlitzer began producing organs with built-in percussion that could be optionally triggered by any key on the manuals or bass pedals, it stopped producing the Side Man. The Side Man’s successor was the Swingin’ Rhythm, a solid state drum machine available as both as a compact standalone unit, and as a built-in option on many Wurlitzer organs.