Thanks, I verified the sketches twice, there's no open wire. Fun fact, if I delete all the other objects, Freecad can happily make the loft...

Thanks a lot, lot of extremely useful points.

I was able to make what I wanted. I share my basic box model here, all dimensions are from the spreadsheet. I'll add more complexities for my personal project. https://drive.google.com/file/d/1VGQb9p0G_uOlvEQuEZNkt2TiBsSuiA73/view?usp=sharing

Aslo, Is there an easy way to retrieves all the sketches with dimensions in order to print it ?

Thanks. I haven't told the whole story. In fact one of the tweeter is also dead. As I don't plan to invest for such an old piece of hardware (I'm not even sure they are particularly good to begin with), I had the idea to replace both tweeters with a pair of Visaton FR8JS who are cheap, have convincing specs and will fit perfectly in the hole of the previous tweeters. I did not find a match for super tweeters ( and I don't want to modify the cabinet). The crossover circuit is easily accessible (solderer on the other side of the connectors plate) so il would try to bypass the crossover.

I will try a AC filter if I can find one at a decent price.

I had a similar room configuration, I placed the surround speakers on the floor against the wall on each side of the sofa, pointing upward. They did the job to surprise me when watching horror movies when there's something making sound behind you.

I moved the sketches for the loft so they won't intersect the main box. And it works that ways. It's strange, and I'm not sure it's the real reason it failed before.

Thanks, I created a first sketch+pad for the top plate on the XY plane, the the side plate on the XZ plane, now the side plate sit at the center of the top plate, how should I move it to the side of the top plate?

Thanks. I just discovered the spreadsheet and aliases, pretty straightforward to use the values in the sketch. Now I have yet to find out how to create multiple parts.

Will I get the high frequencies back if I remove L2?

Thanks, I will do that.

That's my question, how do I get rid of the crossover. In my limited understanding of electronics, the c3 capacitor will do nothing if terminals 11 and 12 are open. I'm not sure though.

3D printing, I plan on placing the left angled side (of the top left sketch) on the printing bed, this way I should avoid supports.

at the price of losing my warranty unfortunately.

After further reading about filters I ended as the same conclusion as you. I first thought the L2 was removing high frequencies, but it is in fact an LC filter to remove bass more efficiently.

thanks, I'll try that. so far I only used the Part Design and Sketecher workbenches, I'll try the Draft.