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Discussion Starter · #1 · (Edited)
Hi everyone, i've been lurking on this forum for almost a year and finally made some modifications to my CRZ.

It's a 2015 Base Manual, rebuilt title, and my first car :)

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First off, I added some sound insulation, that means almost everything in the interior had to go. It was quite easy and fun to disassemble everything.

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First layer is vibration dampening material, full coverage is not needed.

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Second layer is soft 6mm thick foam, where more coverage equals better results.

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Sadly I didn't do a baseline measure, but music quality increased a bit. If you want truly good sound isolation, this car is not for you.

Next post is about the subwoofer build.

4 Posts
Discussion Starter · #2 ·
Anyway, next up is the subwoofer. I have a USA model, so only cargo in the rear seat area is available. I had an idea to use this space for a subwoofer enclosure. So I took measurements of all the rear seat area panels, made a 3D model in Solidworks, and tried to come up with a box design.

Here is the "seats" (plastic buckets) part:

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And with the top seat part folded:

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I decided to use a 8" 350W Alpine subwoofer, and doing some basic calculations in WinISD, my enclosure should have about 25 liters of volume, and about 95cm long port with a cross section of around 88 cm^2 in order to have a flat frequency response and a quiet port.
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I wanted to flush mount the speaker, but unfortunately the was not enough internal volume. So this was the final design:

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The right side of the box is the port, and the left side is the internal volume. Here is the top down view:

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I made some sensors in Solidworks to help fine tune the requirements. Measurement1 tells me the port length.

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4 Posts
Discussion Starter · #4 ·
Building time!

I used 12mm thick MDF and wood glue to make the box. Since I have access to a CNC machine, I prepared a program to cut all required parts. Some parts were damaged during cutting, but no big deal.

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After some test fitting I realised I made one major mistake when measuring the dimensions, but I managed to patch it up.

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I tried to use all the disassembled panels for a factory look.

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Almost done! The top and bottom parts are removable.

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Easy access to turn the amplifier knobs

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And that's it! The sound quality is amazing from this subwoofer and a very much welcome addition. Now the midrange speakers need upgrading.. Maybe someday!
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