Out of line

[brucegseidner]

What is the rationale for rear firing high crossed tweeters when filing in FR drivers?

Is this to preserve the FR magic of single source coherence?

That said, at what frequency does this become self defeating and interfere with the sound stage and the fact that we are using left and right drivers to create the illusion of the original source, ie the placement of different sources, voices, in physical space.

I am used to thinking in terms of front firing time aligned tweets and have been scratching my head reading about rear firing tweets.

[rjbond3rd]

Hi Bruce, speaking strictly as a newb:

Lots of fullrangers run out of treble at 14k, 16k etc. Also, the larger drivers are beaming well before that point. So the rear-firing tweeter just puts a little sparkle on cymbals etc. above that point, and gives a better balance off-axis compared to, say, a beaming 8" FR.

You can't really time-align a fullranger + supertweeter very easily for many points in space. Also, it's not really true that fullrangers have no phase shift whatsoever. Aside from phase anomalies contributed by the driver itself (Doppler distortion, etc.), some cabinets are designed to take advantage of certain phase shifts (e.g. ported box, BLH).

Maybe a guru will chime in on this to clarify or correct.