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Discussion Starter · #1 ·
TL;DR: The ported plates had worse performance than "sealed".

I haven't been happy with the midbass performance of my front stage: A pair of Alpine SPX-17PRO components in the factory locations.

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I modelled the speakers in WinISD using a sealed volume matching my best guess for door volume.

Rectangle Slope Font Parallel Screenshot


This matched the output I was measuring via my RTA: a rolloff under 100Hz - minus a couple of big peaks that could probably be explained by cabin gain or something:

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I decided to model what this would look like if I somehow incorporated a port into the door.

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Well, that looks great (as far as output, at least). I only need a port of diameter 1.75" and depth of 1.5". I can easily achieve that by stacking wood. So I decided to rough up a speaker plate that would achieve this:

Wood Art Tool Gas Paint

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Yes, it's rough. But you get the point.

I forgot to take a picture of it mounted up, but you can imagine how it would look. There was a bit more modification past this to get the plate to mount up nicely in the factory location.

Measuring the output with the same RTA, mic, and position, you can see that the output (ported plate is in green) actually suffers below 500Hz.
Product Rectangle Slope Plot Font


I confirmed that everything was sealed up tight to the door. Seems there are some other acoustical factors at play. Too bad.

Anyway, given that I spent the evening working on this I figured I could at least share my findings. Cheers!
 

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Are your doors well deadened and sealed, and using speaker rings on the doors? Both of these things can help midbass tremendously.

Thanks for sharing your project!
 

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a door really can't be sealed. Unless you built a separate speaker cavity for the speakers. because doors have a few quarter sized holes at the bottom for water. And others
 

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A leaky sealed box still works ok, a leaky ported box doesn't work anywhere near as well.

If you want to port it, you need a proper enclosure not a door. Lots of ways to go about that in a door or in the kick panels, many great examples on this site..
 

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Discussion Starter · #8 · (Edited)
Thanks for the feedback everyone. I should have mentioned that I never expected the door to behave like a perfectly sealed enclosure. However, in the fusion, they're actually quite well sealed from factory.

This is not my door, but this is what they look like. The only real place for air to escape is the window slot and maybe a grommet or two.

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So I figured, given that it's close to sealed it would be worth a try since it could be an easy project and maybe have good results.

In the end it wasn't that effective. I'll be looking into kick panels next.
 

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I'll repeat it for the people in the back. My purpose here was simply to try it and share my findings.
Experimentation is a wonderful activity and there is always something to be learned by the effort , well done and thanks for sharing !
 
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