4th order sub parameters? What parameters to help decide.

[pmcalis1]

This isn't a Vs thread or best sub thread.

I am just wondering what parameter criteria helps choose if a sub will perform well in a 4th order. My buddy is starting a blow through build on a f350 and just trying to see what type of subs perform well in a 4th depending on parameters.

Thanks for any help

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[Massive spl]

Pretty much anything sundown lol

 

[pmcalis1]

Lol well true... But the science why lol.

He's looking at the zv4s. I'm trying to talk him into 4 of the teams. He's got stupid money but so wishy washy on what to do

 

[ciaonzo 5,000+ posts]

A 4th order is essentially a subwoofer in an optimal selaed enclosure, with vented enclosure attached to the 'front' of it. The goal from back in the day was to take a driver, that was only so loud in that sealed enclosure, and make it louder by making it more efficient with the addition of that vented chamber. The trade off was/is bandwidth. Pick any driver that is best suited for sealed enclosures and you will have a great candidate for a 4th order. This would be a driver with plenty of excursion, a medium to medium-high Qts figure, a relatively low Fs, and a respectable BL figure.

 

[pmcalis1]

A 4th order is essentially a subwoofer in an optimal selaed enclosure, with vented enclosure attached to the 'front' of it. The goal from back in the day was to take a driver, that was only so loud in that sealed enclosure, and make it louder by making it more efficient with the addition of that vented chamber. The trade off was/is bandwidth. Pick any driver that is best suited for sealed enclosures and you will have a great candidate for a 4th order. This would be a driver with plenty of excursion, a medium to medium-high Qts figure, a relatively low Fs, and a respectable BL figure.

Thanks this is what I was looking for. So some good values high xmax. Qts of what .5 or higher. Fs=?? Bl=??

 

[ciaonzo 5,000+ posts]

Thanks this is what I was looking for. So some good values high xmax. Qts of what .5 or higher. Fs=?? Bl=??

Sure, no problem.
Yeah, .5 - .7 is real nice. It can be a bit lower if BL is stout. I would shoot for a BL of 15 or higher. There's a bit more to it than that, depending on Re and Vas, but that will get you in the neighborhood.

When you start modelling this, watch your port velocity closely. Don't choke the driver with a small diameter vent.

 

[pmcalis1]

OK I got you I appreciate it. I am doing 4,6,or 8 ethos in a 4th soon as I can wall it. Got four now below window line. I know they do well in 4th orders now I know why. Now just to help my buddy on deciding his subs