There are several versions 2, 4 or 6 channels. Mine has 6 channels.
My MODEL Has upgrad for 48 programs instead of 24 plants originally.
The OB-SX uses the same connectors as the OB-Xa than a monophonic audio output only and input / output CV / Gate. We gat.
The keyboard is also smaller.
Trs simple, no t to be programmed prvu but just to be prt of the use scne having CONTRL on the envelope and filter each sound.
It's the sound of the OB-Xa in a little warmer, fatter (who could believe it?).
I have not used much because it ncessite RVision a complte, several channels can not fit properly and an envelope filter appears damaged.
At worst if I do go out, I will serve as spares for my OB-Xa as it did not cost much.
That said if you are looking for the OB-Xa for cheap when you turn to the MODEL.