[domasmns]

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

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.

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

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

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.

 

[domasmns]

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:

And with the top seat part folded:

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.

I wanted to flush mount the speaker, but unfortunately the was not enough internal volume. So this was the final design:

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

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

 

[ryanthegreat1]

You forgot the mass loaded vinyl in your sound isolation. The foam goes down as a vibration barrier between the body of the car and the mass loaded vinyl. The foam alone doesn't stop sound.

 

[domasmns]

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.

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

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

Almost done! The top and bottom parts are removable.

Easy access to turn the amplifier knobs

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!

 

[domasmns]

Also, don't forget to wire in your LED lights while the interior is disassembled!