Tuning frequency help

[SlugButter]

Where are you seeing the excursion specs on the slaps?

 

[spokey9]

I'm getting told that going ported won't really being an option because of space...but I can't find pr's for my sql-15's

 

[Doxquzme Premium Member]

Passives are very simple to tune, you just add subtract weight (usually in the form of fender washers) until you hit your tuning frequency. Beats the hell out of finding out your real tuning frequency is too high and you have to rebuild your slot ported box. Additionally, PRs can be adjusted to different frequencies depending on your mood. Lastly, there's the space advantage.

The downsides are cost and depending on application you may need 2 (per sub) or run out baffle space. PR's get out phase below tuning almost immediately so the SSF has to be set tighter.

Okay, yes and no. Adding or subtracting weight on 4 radiators is not easier than cutting a 4-6” hole and running various, pre-established (tuning length) sections of PVC, sections which in most cases is only going to be maybe two or three say 35Hz, 30Hz and 25Hz lengths, all of which can be done without removing anything else, jus slide the port in, test, add sections, test and decide. If you’re like me you have a boat load of that material around anyway, I start with the shortest and add pre cut sections you can just tape on to the outside to extend the port. They don’t have to be flush or anything while testing, they can just be added to the face of the cabinet and stick out until you get the desired turning point. Different story if you are using a rectangle vent, understood. In this instance, passives would not only be expensive but you would need such a large area that you would really compromise the integrity of the box. 4 18” passives take up a lot of area, might take up ½ the surface area of the cabinet, and yes, it would be very expensive endeavor if done right. Don’t get me wrong, I’ve made some killer PR subs, done right they sound very nice but you rarely see this in a car. I ran this driver through BASS box pro and at 31Hz-35Hz it came out pretty nice. I can figure single or multiple slot ports, triangular ports or round ports if anyone wants that info. The program allows for various sizes to be input and projects vent air velocity and driver extension/excursion to power limits too. For those that don’t want to purchase software, visit the12volt.com. It has a pretty simple calculators that are pretty accurate for all sorts of audio calculation needs.

 

[Jimi77 5,000+ posts]

Okay, yes and no. Adding or subtracting weight on 4 radiators is not easier than cutting a 4-6” hole and running various, pre-established (tuning length) sections of PVC, sections which in most cases is only going to be maybe two or three say 35Hz, 30Hz and 25Hz lengths, all of which can be done without removing anything else, jus slide the port in, test, add sections, test and decide. If you’re like me you have a boat load of that material around anyway, I start with the shortest and add pre cut sections you can just tape on to the outside to extend the port. They don’t have to be flush or anything while testing, they can just be added to the face of the cabinet and stick out until you get the desired turning point. Different story if you are using a rectangle vent, understood. In this instance, passives would not only be expensive but you would need such a large area that you would really compromise the integrity of the box. 4 18” passives take up a lot of area, might take up ½ the surface area of the cabinet, and yes, it would be very expensive endeavor if done right. Don’t get me wrong, I’ve made some killer PR subs, done right they sound very nice but you rarely see this in a car. I ran this driver through BASS box pro and at 31Hz-35Hz it came out pretty nice. I can figure single or multiple slot ports, triangular ports or round ports if anyone wants that info. The program allows for various sizes to be input and projects vent air velocity and driver extension/excursion to power limits too. For those that don’t want to purchase software, visit the12volt.com. It has a pretty simple calculators that are pretty accurate for all sorts of audio calculation needs.

Why the fudge are you using 4 PR's?

 

[spokey9]

Why the fudge are you using 4 PR's?

He's building the wall

 

[Doxquzme Premium Member]

Why the fudge are you using 4 PR'

He's building the wall

Yeah, but mexico is paying for it!

 

[Doxquzme Premium Member]

Yeah, but mexico os paying for it!

He's building the wall

I thought this design question invloved two 18 inch woofers, my bad! Either way, it's still relative in either1 or 2 woofer application. As a general rule, PR desings use a 2 to 1 ratio.

 

[Jimi77 5,000+ posts]

Okay, yes and no. Adding or subtracting weight on 4 radiators is not easier than cutting a 4-6” hole and running various, pre-established (tuning length) sections of PVC, sections which in most cases is only going to be maybe two or three say 35Hz, 30Hz and 25Hz lengths, all of which can be done without removing anything else, jus slide the port in, test, add sections, test and decide. If you’re like me you have a boat load of that material around anyway, I start with the shortest and add pre cut sections you can just tape on to the outside to extend the port. They don’t have to be flush or anything while testing, they can just be added to the face of the cabinet and stick out until you get the desired turning point. Different story if you are using a rectangle vent, understood. In this instance, passives would not only be expensive but you would need such a large area that you would really compromise the integrity of the box. 4 18” passives take up a lot of area, might take up ½ the surface area of the cabinet, and yes, it would be very expensive endeavor if done right. Don’t get me wrong, I’ve made some killer PR subs, done right they sound very nice but you rarely see this in a car. I ran this driver through BASS box pro and at 31Hz-35Hz it came out pretty nice. I can figure single or multiple slot ports, triangular ports or round ports if anyone wants that info. The program allows for various sizes to be input and projects vent air velocity and driver extension/excursion to power limits too. For those that don’t want to purchase software, visit the12volt.com. It has a pretty simple calculators that are pretty accurate for all sorts of audio calculation needs.

I was thinking more along the lines of really low tuned enclosures where you end up with bent ports.

 

[Doxquzme Premium Member]

I was thinking more along the lines of really low tuned enclosures where you end up with bent ports.

Ah, yep, been there done that too!

 

[SlugButter]

Don’t do crack ladies and gentlemen.

 

[spokey9]

Ffs...please don't be ignorant...

 

[Jimi77 5,000+ posts]

For deep bass, I suggest Henry Mancini.

 

[Doxquzme Premium Member]

For deep bass, I suggest Henry Mancini.

Or Bach...

 

[spokey9]