The picture on the left shows the S30 model, equipped with 61 light-weighted keys, with initial touch and aftertouch.
The internal ROM includes the same AWM2 samples available in the top model (24 Mb), but only one Plug-in board can be installed.
Moreover, due to the lack of the mic/line A/D input, the optional PLG-VH harmonizer/vocoder board cannot be installed too.

Nevertheless, S30 can be a good choice for those who like an easy carriage (only 8 Kg.) better than a vocoder function or a weighted action keyboard.

The S90 model features the same 88-note keyboard and the main features of the S80, but the internal ROM has been expanded to 110 Mb, including a multisampled Yamaha S700 piano (with 3 different velocity layers) not found in any other Yamaha keyboard.

The number of available expansion slots for the synthesys plug-in boards has been raised to 3, and the internal arpeggiator now features 248 preset types (instead of the S80 128 types)

The S90 also features a more large display and an USB interface that has replaced the To Host connection.