I used to build speakers when in college (30+ years ago)That's when you could buy 1 inch plywood and speakers better then those installed in most factory systems. Crossovers were nothing more then LC circuits. Well now the good audiophile speakers can't be duplicated for any amount of money or time by an hobbiest. First, even if you are a master carpenter you can't duplicate the resonence damping matrix construction and the anti-diffraction curved front sides of most good speakers. Too much engineering went into their designs (time alignment, FFT tone burst analysis etc). Second the speakers are harder to come buy. Some like Thiel now make all their own that are not for sale. Lastly the nth pole Butterworth etc crossovers are as much engineering as some old amplifiers. All of this is too difficult to duplicate even for a good engineer.
