(03-11-2012, 04:41 AM)it0r0nt0 Wrote: do you know of any other converters that would do the job ?
That I do not, largely because I haven't felt the need to go looking. The Magic Joy Box mostly works for me as-is, I have just today sorted out one of the two disappointments that I've had with it (a fun morning's hack, really, learned quite a bit about USB HID descriptors), and even without the analog part of the L and R controls I've been using it for a couple months now with little incident.
Not to belabor the point, but have you tested the controller you're trying to use on a real GameCube? Have you tried disconnecting and reconnecting the adaptor and then restarting Dolphin? Have you tried using the controller and adaptor with another emulator or game? Have you tried using the controller and adaptor with another computer (such as a Linux or Windows box)?
Most of the other diagnostic approaches that come to mind require the use of some of Apple's developer tools that come with Xcode, or hooking the adaptor up to a Linux box to which you (preferably) have root access.
I don't know what more to say other than to wish you luck.