Go FasTA wrote

Ground attaches to the female connection on the tweeter. You only use one of the other connections from the crossover. The -3db will reduce the tweeter output by 3 decibels. You can use this to reduce the high frequency output if you find it to be too loud relative to mid and bass tones.

TheACN wrote

Got it thank you. I didn't expect to have to output levels on a crossover but hey never too late to learn

TheACN wrote

Hi,

So I bought a set of Focals for my X5, but I'm lost at the crossover wiring. See the picture, the three cables on the left are form the crossover, which read Ground, 0dB and -3dB. Ground cable has a blue line. The tweeter cables are on the right. No label except the one with the blue line is a male other is female.

So; since crossover has 3 cables and tweeter has two,

Tweeters blue lines cable won't fit crossovers blue line cable (labeled ground) since they're both male.

PS. Focal install videos on youtube are useless. Does not show any detail whatsoever. The user manual that came with it is also useless, just has specs and no info on whats what.