Help CrossOver for FR125s + G2si Tweeter

I will re-build my speakers, i was using a single FR125s and now i want to use two FR125s (want more SPL) + G2Si Tweeter-

Will use a sealed box with 25L (or bigger if some recommend me that will be too small) and will add the tweeter. Can someone please recommend me some crossover design? i think that will cut the tweeter high than the 2.5khz (as manufacturer recommends) (close to 3,5khz will be ok?) can someone please help me with the Xover design?

Sens of G2Si are 96db and 6ohms
Send of FR125S are 86db and 7ohms (will get close to 4ohms because will use two)

Second Order Bessel XOver show me something like in a website

(4.3uf / 0.47mH) for the tweeter and (6.5uf / 0.31) for the woofer

its ok?

I need something that reduce the sensibility of the tweeter, right?


is possible to get some troubles with sound if just get 100mm depth? i want to get as flat as possible the cabinet, because want to put it close to the wall and dont have enough space

*Sorry for my english

Thanks in advance.
Last edited:
The FR125s should not be side-by-side, arrange them vertically. I'd arrange them with the FRs vertically as close as possible and mirror imaged tweeters off to the side to minimize the centre-to-centre.

I might have a RAW acoustics XO for this combo, but i'd have to get permission from Al to post it. Bob @ CSS can probably give you an XO, he ceratinly had an MTM but it may have been with the 16Ω WR125.