so.. Active.... what's does it really mean?

[Philbiker]

Ok, riddle me this...

The stock MEC's in my Thumb as as far as I'm aware active.

When I ordered my Corvette fretless, it was advertised as active, but came with MEC 'Dynamic Correction' p/ups that turned out to be passive. As such, with the preamp and in any positions other than both p/ups full on, it was noisy as hell. I got the p/ups switched over to the same MECs, and noise gone.

However, when the battery runs low and the volume drops, I can switch to the bypass mode and get full signal again. But surely truly active p/ups require power. So are these really active or not, or perhaps does bypassing the preamp feed the remaining juice to the p/ups?

Your bass has passive single coil pickups with an active preamp.