speaker dispersion

[malcom_xavior]

I was reading this tutorial on passive crossovers...
http://passivecrossovers.com/
and was a little confused on the section about speaker dispersion. How do you fix the gap in your frequency in an off axis position? Can you do it without adding a third speaker?

[tsmith1315]

How do you fix the gap in your frequency in an off axis position? Can you do it without adding a third speaker?

That's one of the really sticky points in car audio. Obviously, the ideal solution is to get the speaker on axis.

Some generalities:

-It helps if you can view off-axis FR plots of the speakers you're considering.

-6" two-way systems are almost guaranteed to have a dip in off-axis response unless your tweeter can go very low. In this case a tweeter with a large rear chamber (and lower Fs) would be helpful, but power handling will be reduced, and they are typically large.

-4" two-way systems will have better off-axis performance in the crossover region because of the smaller radiating area. But, they will lack in midbass. Choosing a long-throw 4" that was designed for midbass use and using a proper enclosure for it would be make this route viable.

-Consider all aspects of speaker system design when making each choice involved with that design.

In other words, there ain't no good "fix" for this problem beyond careful, thorough, creative arrangement of crossover design, speaker choice, and speaker placement. It ends up in a juggling act.

Tim

[Bose(o)]

Fixing dispersion off-axis is applying boost based on your off-axis measurements. Of course, if you boost it based on this, your on-axis response will have a +x dB. peak the length of your affected frequencies.

In cars however, dispersion is increased because of the many early reflections from the car's interior. Meaning, you can run drivers that would typically run up to 2500Hz. up to 3000-4000Hz. of course, measuring the speaker will be the true way to determine how high you can 'run' the speaker.