Port vs. PR - midrange quality

[noah katz]

I'm working on the design for a 2-way using the Eighteensound 12ND710 and BMS 4552ND on XT1086 horn/waveguide.

The woofer has a very low Q and the only way to get useful low end is by using porting or PR.

At first I assumed a PR would be less problematic than a port as far as midrange coloration, since the latter gives a direct path for sound to escape from the cabinet.

Upon further thought, the PR is not opaque acoustically and has a much larger area. Fb will be about 55 Hz, so the PR will have a regular cone.

Given how much sound passes through a solid wall, I imagine a cone lets a lot through.

Does anyone know of any studies where a port or PR was mikede for the midrange freq?

The only data I've seen was in LDC, where Dickason covered only blips in FR due to "mutual coupling", whatever that means.

Thanks

[sreten]

Hi,

Stereophile have loads of graphs of port output.

/sreten.

[noah katz]

Good point!

I looked here

http://stereophile.com/floorloudspea...ef/index3.html

and see that after a few hundred Hz the port is 25 dB down, and that they commented on the colorless midrange.

I'll keep the ports as far from the woofer as possible, and create a labyrinth of 1.5" foam that should absorb the midrange but be transparent to bass.

Thanks