It seems that vertical driver placment is the correct design, however, why one of the commercial best speaker ds 5000use horizontal driver placement for their mid to higher speaker. Wouldn’t cause dispersion and time alignment problem ?
it depends on the situation, a vertical orientation of the drivers will give most frequency errors in the up-down direction, with horisontal orientation you will have most errors in left-right direction, and that is why coaxial drivers are so appealing
