port vs passive radiator

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=98670
Printed Date: May 11, 2025 at 11:20 PM

Topic: port vs passive radiator

Posted By: jmelton86
Subject: port vs passive radiator
Date Posted: November 05, 2007 at 7:34 PM

What are the major differences between the two, besides no port noise and price ($100 for PR VS $15 for port materials)?

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001

Replies:

Posted By: aznboi3644
Date Posted: November 05, 2007 at 8:41 PM

differences??

For the PR you don't have to sacrifice any room for the port volume.

I have never heard a PR system...I usually just stick to ports.

Posted By: DYohn
Date Posted: November 05, 2007 at 9:05 PM

The difference is that PR systems have a slightly higher roll off and a secondary resonance at the PR fs. HERE's a good description of the differences.

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Posted By: jmelton86
Date Posted: November 05, 2007 at 9:10 PM

Thanks for the link. So PR's would have a better response b/c of the higher rolloff? The secondary fs would be the 'tuning' frequency of the PR?

Thanks for all.

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001

Posted By: DYohn
Date Posted: November 06, 2007 at 12:01 AM

PR systems don't necessarily have "better" response, but they do allow better control over the woofer so there's less chance of "bottoming" it. PR systems have by far the worst performance of any standard alignment when it comes to group delay, which tends to make them sound slow or flabby and will definitely affect the car's transfer function if you're looking to maximize SPL. This is why I don't like PR systems as a rule: too much delay in the output and it tends to be in the audible spectrum in a car.

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Posted By: jmelton86
Date Posted: November 06, 2007 at 12:15 AM

Makes sense. So, the PR just kind of slows it down?

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001

Posted By: tcss
Date Posted: November 06, 2007 at 5:59 PM

Slightly off topic. I had a customer ask me if I've ever done a box with a compassionate radiator. You know a radiator that cares deeply about things.

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There is no such thing as free installation!

Posted By: jmelton86
Date Posted: November 06, 2007 at 6:40 PM

DYohn wrote: PR systems have by far the worst performance of any standard alignment when it comes to group delay, which tends to make them sound slow or flabby and will definitely affect the car's transfer function if you're looking to maximize SPL. This is why I don't like PR systems as a rule: too much delay in the output and it tends to be in the audible spectrum in a car.
jmelton86 wrote: Makes sense. So, the PR just kind of slows it down?

1. Transfer function, SPL. How about SQ? Will it seem like it's delayed more than usual? Can time-delay comphensate for this?

2. How about box size; will a larger box slow it down more? The tech support admin from Boston told me that larger boxes (other than the recommended .5cu' for 1 10"G5 with a GTR PR -I had them in a 1.8cu footer at the time) will possibly damage the active driver as there's not direct pressure on the PR so it makes the sub move too far -basically what he said.

tcss wrote: Slightly off topic. I had a customer ask me if I've ever done a box with a compassionate radiator. You know a radiator that cares deeply about things.

Compassionate radiators are a very good thing. We always need to radiate more compassion posted_image

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2013 Kia Rio -90a alternator
DDX470HD GTO14001 GTO1014D (x3)
Big3 in 1/0G
1/0G to GTO14001