Passive Radiator

[bk12321 10+ year member]

Actually the "simple delay explanation" and how it replicates a port explains all of that when you consider that the PR has inertia just like the air in the port and the inertia of the PR moving in phase with the primary driver increases the pressure in the box and mass loads it, reducing excursion. Also because the PR is moving, its swept volume couples with the primary driver creating a coupled output that increases SPL compared to just the primary driver in a sealed box.

just curious, but do you have a major in car audio/some field in electronics, or are you just an audio enthusiast?

 

[helotaxi 5,000+ posts]

Just an enthusiast. Degree is in economics but had classes in EE, Aero, Astro, Thermo, CE, mech and stats. Work with C-band and Ku-band comm equipment a lot.

 

[dcole18 5,000+ posts]

Just an enthusiast. Degree is in economics but had classes in EE, Aero, Astro, Thermo, CE, mech and stats. Work with C-band and Ku-band comm equipment a lot.

lies //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[DidUHearThat? 10+ year member]

A passive radiator system doesn't stress the powered driver any more than a ported setup does. It has the same effect and works in a similar manner to a port. The suspension and mass of the PR creates a delay in the PR movement that brings it into phase with the primary driver. It allows you to tune a small box low without needing the space taken up by the long port that would ordinarily be required for a low tuning. The main drawback is that you usually need about 2x the cone area/swept volume of the driver in passive radiators, so, for example a 10" sub might require 2x10" radiators or 1x15" radiator.

I never said it did. Both would change the impedence of the main driver and the amp. It does "stress" the main driver more than not having the PR in a sealed box. It's a minor hassle to calculate the effect of passive radiators, they do behave differently than a port.

I am not a speaker designer, but the info I posted is what I have been told by speaker designers I have worked with. Given the hassle and expense of adding passive radiators you might as well just add another standard driver and power it. They seem most usefull in small, odd shaped, low power systems; like computer speakers, t.v's and monitor cubes where large drivers are not practical.

 

[mrogowski 5,000+ posts]

Watch Helo, he's a wolf in sheep's clothing when it comes to car audio...

Throwing a Passive Rad in a vehicle would be pretty cool actually. You could build a box to hide a 10" sub and use a 15" passive that your passengers would see. They would think you are running a 15" sub then...

 

[thch 10+ year member]

Actually the "simple delay explanation" and how it replicates a port explains all of that when you consider that the PR has inertia just like the air in the port and the inertia of the PR moving in phase with the primary driver increases the pressure in the box and mass loads it, reducing excursion. Also because the PR is moving, its swept volume couples with the primary driver creating a coupled output that increases SPL compared to just the primary driver in a sealed box.

that would seem to be an important part of the explaination. After all, without it you might as well just say, "oh, its supposed to be that way".

"The suspension and mass of the PR creates a delay in the PR movement that brings it into phase with the primary" isn't true and really sounds very close to the first misconception of: http://www.hometheaterhifi.com/volume_5_2/cmilleressayporting.html

in anycase, its probably not worth arguing over further, given the amount of information on the subject that google can provide.