View Single Post
  #27   Report Post  
Posted to rec.audio.pro
gregz gregz is offline
external usenet poster
 
Posts: 131
Default 12" passive radiator replacement?

nickbatz wrote:
On Tuesday, January 7, 2020 at 8:05:09 PM UTC-8, Trevor wrote:

A lot of passive radiators are tuned by adding mass to the cone. So if
you can measure the bass response, it will be cheaper to simply adjust
the cone mass. Cheaper still to throw away the PR and tune the box with
a port.


That's beyond my ken.

I mean, I can measure the bass response, but I have NFI how to tune the box with a port.


Port or passive start out measuring impedance. The passive or port will
reduce woofer excursion over most of the low bass range, to almost none.
Selecting a frequency say around 50 Hz, putting hand near port will make
woofer move more. Adding some sticky gum to passive will do same thing. I
would first measure passive resonant frequency to see if it's proper. You
can visual tune very close to same watching impedance plots. Converting to
port is not always possible. Some of the other aspects get complicated, as
I read a very nice write up on the subject, beyond what I wanted to see.

Greg