Hi all.
In response to the question regarding what synthesis engine is used in the Fantom-S and Fantom-X, I thought I'd post a brief (and probably incomplete) history of Roland's digital synthesis as it relates to the Fantoms.
L/A
Most of Roland's sample playback synths (excluding the VP-9000, V-Synth, and VariOS, for example) are based on the original synth architecture found in the D-50, which used the L/A synth architecture (Linear/Arithmetic). That architecture used 4 Tones just like the Fantom. Of course, it was much more limited than the Fantom in many way, but it did basically the same thing... played back samples and filtered the sound with filters and LFOs.
Super-JV
The L/A synth architecture was greatly improved upon with the Super-JV synth engine (preceded by the JV synth engine which was also based heavily on the L/A synth engine). The JV and Super JV engines added, among other things, resonant filters that could be adjusted in real-time. I have no hands-on experience (yet) with the L/A, or JV engines, only the Super JV engine so I'm not highly familiar with the exact differences.
XV
In 2000 Roland released the JV-5080 which improved on the Super JV synth engine by adding 64 notes of polyphony, stereo Tones, more extensive Matrix Control and additional filters. The Fantom FA-76 was released about the same time with the same engine, but limited to 64 notes of polyphony rather than the 128 of the XV-5080. The Fantom-S added the ability to use user samples and multi-samples just like internal waveforms, a step LFO, and a different effects unit (MFX rather than the EFX unit found in the XV-5080). I've owned an XP-80 (Super JV engine), XV-5080, and now the Fantom-X8.
Regards,
Nathan Sheldon
http://www.nathansheldon.com/