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closeups of Wurlitzer Sideman

The electronics chassis. Tube complement is one 6AV6, two 6C4, one 6BA6, and five 12AX7s. The trimpots control the resonance of the bandpass filters that make the drum tones. “SHIMMER GENERATOR” controls the decay time of the noise-based cymbal sounds. The inside of this chassis is quite impressive. Maybe later. (Does anyone out there have the schematic for the Sideman? Just curious. Repairing it is straightforward, but how this thing works is becoming interesting to me.)

Wurlitzer Sideman electronics chassis

closeups of the Wurlitzer Sideman

This is the control panel. It’s quite difficult/costly to get that kind of chemically-etched brass panel made today. The BLOCKS and CYMBALS knobs are rotary selectors that provide five different variations for block and cymbal patterns, plus totally disabling them. I must assume some of those home organists found a use for this–because the amount of switching required to implement the function is frightening. Above the start and volume knobs are two neon lamps that flash in time with the rhythm.

Sideman control panel

More of the Sideman internals

Here is the left side. 9 tubes in the sound section, and a power amp made with a 12AX7 and two 6BQ5s. 2-way speaker with two tweeters, one coaxial with the woofer and the other on the front of the cabinet, under the control panel. The big aluminum disk turns the contact arm–it is driven by the motor thru a rubber belt and a rubber idler wheel. The speed slider on the control panel drags the idler on the disk, closer to the center and the rhythm runs faster. Power is shut off by pushing the slider all the way rearward. All the tubes in this thing were original, dated 1958, and still good.

Sideman LH side view

The world’s first electronic drum machine–the Wurlitzer Sideman

sidemansideview.JPG

I’m fixing this one for a friend. Introduced 1958. In this view we see the “pattern sequencer” — a large printed circuit board (the only one in the unit) with a set of contacts on a rotating arm. The contacts close circuits and generate trigger pulses, which hit vacuum-tube ringing filters to generate most of the drum sounds. This unit was in remarkably good condition, if you don’t count the ugly black padded naugahyde someone put all over the outer cabinet.

old circuit-bent keyboard

This was a horrible Chinese combo keyboard (no brand name) I found long ago, at a Longs Drug store for $5. It contained exactly one chip on a tiny PC board – plus a lot of buttons and a 3-octave keyboard. I cut it down and installed it in a small box. Switches allow you to misconfigure the scanned function-selector buttons, the knob drags the pitch waaaay down. Instant Skinny Puppy happy pop music. Runs on 4 AA cells.minibentkeyboard