Custom Sequential Circuits Prophet 10 Minus Keyboard

via this auction

"This unit, serial number 1010-0078, is the final production version of the Prophet-10 designed around two Prophet-5 Rev 3 voice boards. It has enhanced microprocessor control circuitry and software to provide 10 polyphonic voices (2 VCOs each) in four keyboard modes with responsiveness comparable to the Prophet-5. These modes allow the choice of separate polyphonic control of two 5-voice synths, combined control of a “stacked” pair of 5-voice synths, alternating notes between two 5-voice synths, or control of a single 10-voice synth. Additional features not found on the Prophet-5 include programmable 3-band equalization, two control voltage pedal inputs with assignable routing, three foot switch inputs and a 10,200 note polyphonic sequencer. It is equipped with Sequential’s MIDI interface kit and the latest firmware, Rev 6.1. Recently the unit was thoroughly tested, repaired and burned-in by Wine Country Sequential in preparation for sale.

If you are familiar with the Prophet-10, you are probably wondering what happened to the keyboards on this unit. Although the stock Prophet-10 with its twin manuals is a sight to behold, the inclusion of two keyboards makes the nearly 3-1/2 foot by 2 foot by 8 inch, 70 pound unit so cumbersome that it is difficult for one person to move it by themselves, and difficult to integrate into a small studio environment or performance setup. As well, with the advent of MIDI controllers and sequencers and availability of the Prophet-10 MIDI upgrade kit, the built-in keyboards became redundant. At least a few ardent but frustrated Prophet-10 users dreamed of a slimmer instrument without the keyboards.

While I was employed as a service technician and visiting E-Mu Systems in the late 1980s, I happened to mention this to a product design engineer there who described to me a simple solution he referred to as “The Riley Mod.” It turns out that all the structural members forward of the main control panel can easily be unbolted and removed except for the sides of the chassis frame. The keyboards, modulation wheel and sequencer modules are simply unplugged from the rest of the synthesizer, unbolted and removed. Then the sides of the chassis frame can be cut back in line with the new forward face of the enclosure created by reusing a long corner piece and sheet metal that was part of the keyboard enclosure. Likewise, the wooden end pieces are carefully cut back to match the new enclosure dimensions and refinished to match the original look. Voila!

As you can see in the photos, the end result resembles an Oberheim Xpander, but with the familiar Prophet-10 control panel and no keyboards. This reduces the depth of the instrument to 13-1/2 inches and weight to 43 pounds – a much more practical size for lifting, transporting and integrating into an electronic music studio or performance system. For example, this slim rendition of the Prophet-10 rests comfortably on an Apex column stand.

NOTE: The circuit boards contained in the synthesizer unit are unaffected by the “Riley Mod” and have not been modified in any way except for installation of the factory-supplied MIDI upgrade kit..."