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· Registered
33 Posts
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:

Rectangle Slope Plot Font Line

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

Rectangle Product Slope Font Parallel

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

Wood Eyewear Flooring Office supplies Nail

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!

· Registered
33 Posts
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.

· Super Moderator
592 Posts
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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