It was a difficult decision, putting the JD-800 on the list in lieu of the massively popular D-50. The latter is arguably the classic between the two and represented a major shift in Roland's approach to instrument design and sales. Yet the JD-800 was, frankly, a far better instrument.
Like the D-50, the JD combined sample-based oscillators with a fairly typical signal path that included a resonant filter, envelope generators and the like. However, the JD-800 offered something not available on any other sample-based synthesizer: a bucket load of sliders. Yep, the JD harkened back to the analogue era, offering scads of real-time control (that, alas, could only be transmitted via SysEx). It was big, impressive and utterly sexy, even if it was made mostly of plastic.
The JD-800 offered something not available on any other sample-based synthesizer: a bucket load of sliders.
More than that, it sounded out-of-this-world. At a time when manufacturers were doing their best to cram as many grainy 8-bit low-rate samples into an instruments' ROM as possible, Roland used only hi-res stuff, resulting in outstanding sound quality.
Alas, the JD-800 was released a decade too soon. The analogue revival was still years off and sales fizzled (at least by D-50 standards). However, Roland knew what it had, and the technology behind the JD-800 would pop up again and again in its best-selling series of rack-mountable MIDI modules.