You have to be hard, sometimes - at Blackheath (when I was running it) I banned Keyboards altogether. This was due to several factors including:

1) Space taken up - people were bringing in FULL sized keyboards/stands aand amps then proceeding to re-arrange furniture to accomodate. With little or no regard as to the seating arrangements of other musicians and the audience!

2) Loud and inappropriate (for a folk/acoustic session)
3) volume drowning out others
4) Artificial Drums/percusion
5) Other synthesised sounds/backing
6) Complaints from other club attedees
7) Complaints from pub staff

I made an announcement and explained why. People were happy at the time, as most of the keyboarders played other instruments as well. I did state that exceptions would be made in special cases and by prior arrangement only.

This worked fine for the year or so that I was MCing!

Mind you since I left that club I've heard that the keyboarders have returned!

I made an announcement and explained why. People were happy at the time, as most of the keyboarders played other instruments as well.