4th order design 2 alpine type r 15's

[4bannger 10+ year member]

I would shrink it a little to try and get the Fc above 40..

how would i go about doing that? just make the sealed section smaller?

 

[SounDrive Pro Seller]

how would i go about doing that? just make the sealed section smaller?

Yes. I threw some numbers together.

3 cubes sealed gives you a sealed resonance of 42. You'd tune the ported section to 42 hz. The ported chamber would need to be 3-6 cubes AFTER displacement depending on your goals - closer to 3 cubes for a wider bandwidth, closer to 6 cubes for more SPL. Optimal port area is somewhere between about 120 and 175 square inches. I would stay on the lower side and also recommend using a large aero unless you plan on doing a lot of testing and cutting back on port area. A 12-14 inch flared PVC aero would be the most efficient.. or a pair of 10" aeros.

 

[4bannger 10+ year member]

Yes. I threw some numbers together.
3 cubes sealed gives you a sealed resonance of 42. You'd tune the ported section to 42 hz. The ported chamber would need to be 3-6 cubes AFTER displacement depending on your goals - closer to 3 cubes for a wider bandwidth, closer to 6 cubes for more SPL. Optimal port area is somewhere between about 120 and 175 square inches. I would stay on the lower side and also recommend using a large aero unless you plan on doing a lot of testing and cutting back on port area. A 12-14 inch flared PVC aero would be the most efficient.. or a pair of 10" aeros.

Thanks for all your help. can you tell me how you came up with that number so I can learn

 

[SounDrive Pro Seller]

Thanks for all your help. can you tell me how you came up with that number so I can learn

I'm on my phone so I don't have the Fc formula in front of me.

For ratios:

1:1 to 2:1 (ported:sealed) ratio is generally more oriented to having a better bandwidth or being daily. 2:1 and up is more SPL oriented and 5:1 is about where returns start diminishing from what I understand.

For port area:

It depends on the vehicle and box, optimal port area is almost always between 1/3 and 1/2 of cone area. It's usually better to go with 1/3 if you're doing a "one and done" box. If you're going to adjust, it's easier to start at 1/2 and slowly cut down.

For tuning:

Tune at Fc for daily and "most" SPL purposes. Some people will play with the tuning for a flatter response or for more SPL at a certain frequency although it's again a lot of testing. Also, aeros are always better than slot ports if the design allows for it. 4th orders are tuned high so the port length isn't usually very long so they work great.

 

[4bannger 10+ year member]

I'm on my phone so I don't have the Fc formula in front of me.
For ratios:

1:1 to 2:1 (ported:sealed) ratio is generally more oriented to having a better bandwidth or being daily. 2:1 and up is more SPL oriented and 5:1 is about where returns start diminishing from what I understand.

For port area:

It depends on the vehicle and box, optimal port area is almost always between 1/3 and 1/2 of cone area. It's usually better to go with 1/3 if you're doing a "one and done" box. If you're going to adjust, it's easier to start at 1/2 and slowly cut down.

For tuning:

Tune at Fc for daily and "most" SPL purposes. Some people will play with the tuning for a flatter response or for more SPL at a certain frequency although it's again a lot of testing. Also, aeros are always better than slot ports if the design allows for it. 4th orders are tuned high so the port length isn't usually very long so they work great.

well thanks for all your help.

 

[4bannger 10+ year member]

I'm on my phone so I don't have the Fc formula in front of me.
For ratios:

1:1 to 2:1 (ported:sealed) ratio is generally more oriented to having a better bandwidth or being daily. 2:1 and up is more SPL oriented and 5:1 is about where returns start diminishing from what I understand.

For port area:

It depends on the vehicle and box, optimal port area is almost always between 1/3 and 1/2 of cone area. It's usually better to go with 1/3 if you're doing a "one and done" box. If you're going to adjust, it's easier to start at 1/2 and slowly cut down.

For tuning:

Tune at Fc for daily and "most" SPL purposes. Some people will play with the tuning for a flatter response or for more SPL at a certain frequency although it's again a lot of testing. Also, aeros are always better than slot ports if the design allows for it. 4th orders are tuned high so the port length isn't usually very long so they work great.

is that 3 cuft per sub or for both

 

[T3mpest 10+ year member]

Running it through winisd real quickly 3-3.5 cubes for each chamber tuned around 40hz should be fine. You can always built it a bit larger in each chamber and tune a little lower and then chop the port and add something to take up space as needed. So I'd start with 3.5 in each half chamber tuned at 40 and you can always work it up or down once you've heard it. It's MUCH easier to know how to make a design like this after you have it in the car and know what you want to change.

 

[4bannger 10+ year member]

Running it through winisd real quickly 3-3.5 cubes for each chamber tuned around 40hz should be fine. You can always built it a bit larger in each chamber and tune a little lower and then chop the port and add something to take up space as needed. So I'd start with 3.5 in each half chamber tuned at 40 and you can always work it up or down once you've heard it. It's MUCH easier to know how to make a design like this after you have it in the car and know what you want to change.

yeah thats true. thanks for your and everyones help. I learned alot. from everyone. Im gonna do some google sketch up designs and post them tonight or in the morning and maybe someone can take a final look at my numbers. im not really looking for a one and done box being that I get all the free MDF from my shop I want...but I i dont wanna make something and it be terrible.

One more question. Im only running 800 rms to them which is way less power than they need. They sound suprizingly loud off the small amount of power im putting to them. would that effect the 4th order. I plan on buying a new amp when tax returns come in but i wanna build the box now.

 

[SounDrive Pro Seller]

yeah thats true. thanks for your and everyones help. I learned alot. from everyone. Im gonna do some google sketch up designs and post them tonight or in the morning and maybe someone can take a final look at my numbers. im not really looking for a one and done box being that I get all the free MDF from my shop I want...but I i dont wanna make something and it be terrible.
One more question. Im only running 800 rms to them which is way less power than they need. They sound suprizingly loud off the small amount of power im putting to them. would that effect the 4th order. I plan on buying a new amp when tax returns come in but i wanna build the box now.

4th orders are very efficient //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif You generally don't want to overpower subs very much in one.

From what I understand, a 2:1 ratio 4th order is around the same SPL level (generally) as a ported box. More ported volume = more efficient but less bandwidth. Conversely, less ported volume is less efficient but gives you a wider bandwidth.

 

[4bannger 10+ year member]

im going to be posting up my deisned 4th order with an adjustable port on it.

 

[4bannger 10+ year member]

I'm on my phone so I don't have the Fc formula in front of me.
For ratios:

1:1 to 2:1 (ported:sealed) ratio is generally more oriented to having a better bandwidth or being daily. 2:1 and up is more SPL oriented and 5:1 is about where returns start diminishing from what I understand.

For port area:

It depends on the vehicle and box, optimal port area is almost always between 1/3 and 1/2 of cone area. It's usually better to go with 1/3 if you're doing a "one and done" box. If you're going to adjust, it's easier to start at 1/2 and slowly cut down.

For tuning:

Tune at Fc for daily and "most" SPL purposes. Some people will play with the tuning for a flatter response or for more SPL at a certain frequency although it's again a lot of testing. Also, aeros are always better than slot ports if the design allows for it. 4th orders are tuned high so the port length isn't usually very long so they work great.

Running it through winisd real quickly 3-3.5 cubes for each chamber tuned around 40hz should be fine. You can always built it a bit larger in each chamber and tune a little lower and then chop the port and add something to take up space as needed. So I'd start with 3.5 in each half chamber tuned at 40 and you can always work it up or down once you've heard it. It's MUCH easier to know how to make a design like this after you have it in the car and know what you want to change.

Okay so here is what i got. the port is adjustable up to a 12x12port. I figured I could make it this way, unless im tottaly wrong and adjust it to my liking with tuning the port. sub are firing into the sealed section as ive heard it may be a good idea so you can smell the coils heating up. I would love to get your thoughts and ideas about this design. I took all your suggestions into though in my design.

View attachment 26546614View attachment 26546615View attachment 26546616

 

[SounDrive Pro Seller]

Okay so here is what i got. the port is adjustable up to a 12x12port. I figured I could make it this way, unless im tottaly wrong and adjust it to my liking with tuning the port. sub are firing into the sealed section as ive heard it may be a good idea so you can smell the coils heating up. I would love to get your thoughts and ideas about this design. I took all your suggestions into though in my design.
View attachment 26546614View attachment 26546615View attachment 26546616

The numbers look good, but the design may need to be tweaked. You don't want to port opening to be right in front of the subs, and you want to avoid having subs firing directly at each other at possible. Do you have room to have the subs parallel with the front of the box?

You may want to shrink the sealed section to about 3 cubes to raise the Fc a little, although it would be fine at 40 for a daily box.

 

[4bannger 10+ year member]

I'm on my phone so I don't have the Fc formula in front of me.
For ratios:

1:1 to 2:1 (ported:sealed) ratio is generally more oriented to having a better bandwidth or being daily. 2:1 and up is more SPL oriented and 5:1 is about where returns start diminishing from what I understand.

For port area:

It depends on the vehicle and box, optimal port area is almost always between 1/3 and 1/2 of cone area. It's usually better to go with 1/3 if you're doing a "one and done" box. If you're going to adjust, it's easier to start at 1/2 and slowly cut down.

For tuning:

Tune at Fc for daily and "most" SPL purposes. Some people will play with the tuning for a flatter response or for more SPL at a certain frequency although it's again a lot of testing. Also, aeros are always better than slot ports if the design allows for it. 4th orders are tuned high so the port length isn't usually very long so they work great.

Running it through winisd real quickly 3-3.5 cubes for each chamber tuned around 40hz should be fine. You can always built it a bit larger in each chamber and tune a little lower and then chop the port and add something to take up space as needed. So I'd start with 3.5 in each half chamber tuned at 40 and you can always work it up or down once you've heard it. It's MUCH easier to know how to make a design like this after you have it in the car and know what you want to change.

The numbers look good, but the design may need to be tweaked. You don't want to port opening to be right in front of the subs, and you want to avoid having subs firing directly at each other at possible. Do you have room to have the subs parallel with the front of the box?
You may want to shrink the sealed section to about 3 cubes to raise the Fc a little, although it would be fine at 40 for a daily box.

well the sub are reverse mounted and firing into the sealed sections. But i was worried about that being a problem. I think im going to make it with two chambers the sealed split in half with 3 cuft in each sealed chamber, and the sealed chamber in front like the first design i posted.Il try to get something together really quick.

 

[4bannger 10+ year member]

okay so here is my revised plan based on your feedback. made the ported sections a bit smaler buy still tuned to around 40hz. the port is still going to be adjustable View attachment 26546617View attachment 26546618View attachment 26546619

 

[SounDrive Pro Seller]

okay so here is my revised plan based on your feedback. made the ported sections a bit smaler buy still tuned to around 40hz. the port is still going to be adjustable View attachment 26546617View attachment 26546618View attachment 26546619

That one looks better. Would an external port be possible in your vehicle? It would be easier to adjust tuning and port area on if you desired.