I think Serge's idea of 'matrice' would be correct if it is the kind of x-y pin matrix once popular for programming synthesizers; however, the mention of 'jack' makes me wonder if this isn't simply a jack field for interconnecting synth. modules. We would really need to know a lot more of the wider context to know for sure.

However, whichever of those turns out to be the correct term, do let's remember that 'patch' in signals applications is very often translated by 'brassage / brasser', and I think that term needs to be worked in here somehow.