Which M1 can become a M1ex, if I have the expansion board with extra waveforms. My motherboard doen't have any slots for it.

I think that the EX mod was intended for the rack mount module, initially. I beleive it has to be hardwired to the board in a standard M1. Call a music store and talk with a keyboard repair tech.

Thank Doug, I was begining to come up with that conclusion, since not many many people have a M1R, and many people don't know what I'm talking about. I'm going to have to sell my expasion board.

Whoa, not so fast, Mauricio. There's nothing wrong with your M1; the expansion board was designed, just like Doug said, to be hardwired onto the motherboard by a tech, rather than the user.

I think I've already talked to you about this in another forum, but for the benefit of anyone else who may be interested in this topic - do like Doug said and talk to a competant keyboard tech (get your local retailer to recommend someone). Installing the ex board is not a really big job (I watched it being done), but if the guy has never done it before and has no idea how to proceed, you might want to contact Korg and ask them for the installation instructions for the ex kit. In any even, any competant tech should be able to do this for you, and shouldn't charge you very much to do it, either.

Cheers - Dave.