Couple of "Engineering" Questions

[ffemtwakeman]

A mechanical siren works by drawing air in from the front, compressing it, and forcing it out then side slots. The idea of the directional cone is to redirect the sound to the front of the siren and not the side. As for recessing a Q, I would think that there is some decrease in the effectiveness if it is mounted like it is on Boston's new rigs, but I doubt that it is really noticeable.