Old fart getting frustrated trying to design an enclosure for my first system build in 10 years


LucaBrasiMN

CarAudio.com Newbie
Oct 13, 2021
3
0
Minnesota
Hey guys,
I am coming back to this community as I have recently decided to get back into car audio. I have been running the same old type-r for 10 years and just recently ordered a 12" DC Level 3. I don't remember having this much trouble finding information and designing a box back in the day. I am looking to put this box directly on the backseat of my silverado ext cab.

I want a ported box 1.5-17 cu ft with sub and port facing up. I have some numbers entered in torres (screenshot below) that I think is close but it won't give me the port cut sizes and am in need of someone who knows what they are talking about to let me know if it will even work. I have also mocked up these dimensions in sub box pro but the numbers don't quite match and I am frustrated it won't let me change the depth of the box. I feel like I am missing something and this is far more complicated than it should be so please help this old fart out.

These designs are meant to be a regular trunk box that I would then flip on its back with sub and port facing up.
 

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1aespinoza

Junior Member
May 22, 2013
1,146
304
Pharr, Texas
I think is close but it won't give me the port cut sizes
It looks like the port is the same height as the baffle. So you will only need to cut 2 panels to form an L-shaped port. Panel 1 is 13x16.5, Panel 2 is 13x10.25. The 13 inch edge of panel 1 will butt against the end if panel 2. This will put it 1.75 inches away from the back wall.
 

LucaBrasiMN

CarAudio.com Newbie
Oct 13, 2021
3
0
Minnesota
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It looks like the port is the same height as the baffle. So you will only need to cut 2 panels to form an L-shaped port. Panel 1 is 13x16.5, Panel 2 is 13x10.25. The 13 inch edge of panel 1 will butt against the end if panel 2. This will put it 1.75 inches away from the back wall.
Ok this helps a lot, thank you. I followed most of those specs from a different build I found years ago and could not make sense to how the port worked. Now would it be possible/make more sense to have a wider port that wont need to form an L instead? 1.75 wide seems rather skinny.
 

1aespinoza

Junior Member
May 22, 2013
1,146
304
Pharr, Texas
1.75 wide seems rather skinny.
From what I have recently read, port width plays an important role in controlling the flow of air which in turn controls the cone. The thin wide port provides a wider contact area of resistance, ergo better control. So widening it may shift the tuning frequency and lose a bit of cone control, which may cause overexcursion.
 
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Buck

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From what I have recently read, port width plays an important role in controlling the flow of air which in turn controls the cone. The thin wide port provides a wider contact area of resistance, ergo better control. So widening it may shift the tuning frequency and lose a bit of cone control, which may cause overexcursion.
That is very true, especially when you're playing music. Port area is hugely important and can really vary system by system. Some subs do well with 8-10 in^2/cube, some subs do better with 16 or even more. Your port is a resistance factor to air flow. It's actually an impedance factor, but the resistance from the port on the air being pressurized in the enclosure is what gives the box it's tuning. Too small of port = too much resistance = limited cone movement. Too big of port = lack of resistance = box doesn't pressurize well too far away from tuning frequency. Fine adjustments of port area can can help your sub move and play in the specific way that you want it to, but keep in mind port velocities change with the frequency being played.

There's also a relationship between port area and frequency. Depends somewhat on the woofer's Fs, but generally you need slightly more port area as you tune higher. There's ways to couple box tuning with port area for a specific bandwidth and peak effect, and the combos for those two things are almost infinite. Understanding the box size, port area, and port tuning relationship can greatly affect bandwidth, the severity of high or low end roll off, and overall peak. Sometimes different vehicles and different port positions within the same vehicle can use different port areas for overall effectiveness, even for the same subwoofer setup. You just gotta know your environment and how you want it to sound.
 
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1aespinoza

Junior Member
May 22, 2013
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Pharr, Texas
different port positions within the same vehicle can use different port areas for overall effectiveness
After 2 weeks of giddily enjoying my w7 ported, I started to wonder of how it would have sounded if I had followed your advice of firing it to a side wall (someone asked you of port direction for an extended cab). Will definitely do that in the next box build. I have a 12" Kove Audio Armageddon that has been giving me puppy eyes for a while now.
 
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