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View Full Version : 4th order design 2 alpine type r 15's



4bannger
01-05-2014, 09:33 PM
okay so this is my first 4th order design that I have done. Most of the info that i got for the design was from the SMD forum. Can someone tell me if this design will work and if not what changes do i need to make this deisgn work. Im sure some of the much more experienced box designers can help me on this.

Vehicle : toyota sequoia
Location in the vehicle: behind third row
Space available (Length x Width x Height): 48x 48x 30
Subwoofer make and model: apline type r
Subwoofer Size: 15"
Number of Subwoofers: 2
Type of Port (Kerfed, Slot, Aero, etc.): 4th order slot port
What type of music do you like?: rap
Is your goal SPL or Everyday Music?:SPL
Tuning Freq (Hz): 45 - 50hz
Volume : max
Questions: will the deign I have work









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4bannger
01-05-2014, 10:49 PM
come on 15 views and no help

RangerDangerV2
01-05-2014, 10:53 PM
I like 4th orders.

4bannger
01-06-2014, 06:42 AM
I like 4th orders.

Would this design be a good 4th oder and would I need to change anything?

SounDrive
01-06-2014, 06:50 AM
I'm on my phone and can't read any attachments. What's the sealed volume, ported volume, sealed resonance (Fc), tuning, and port area?

Type R's seem to be well suited for 4th orders.

Jroo
01-06-2014, 10:22 AM
I couldnt see the sealed and ported volume but it looks like you have a very large ported section and port and smaller sealed section. Usually when you see that, you have a person looking for loud, but just guessing without know specs. Ive had a couple of 4ths but mine were always closer to 1:1 ratios or larger sealed because I wanted low end and more of muscial/flat response and sound.

SounDrive
01-06-2014, 11:34 AM
2:1 ratio and smaller is generally what you want for daily. 3:1 still isn't bad; higher is generally for SPL only..

You have a 4:1 so that's a burp box at this point but may be able to play fine on music, just with more rolloff on the low end... Also there's too much port area. If you're going to adjust, I recommend starting at 1/2 cone area and downsizing until you find a good spot. If you're going for a "one and done" build, I'd do 1/3 cone area as port area.

Figure out your sealed Fc, and if it's acceptable (say mid 40s to low 50s) then tune to that number.

4bannger
01-07-2014, 06:39 AM
2:1 ratio and smaller is generally what you want for daily. 3:1 still isn't bad; higher is generally for SPL only..

You have a 4:1 so that's a burp box at this point but may be able to play fine on music, just with more rolloff on the low end... Also there's too much port area. If you're going to adjust, I recommend starting at 1/2 cone area and downsizing until you find a good spot. If you're going for a "one and done" build, I'd do 1/3 cone area as port area.

Figure out your sealed Fc, and if it's acceptable (say mid 40s to low 50s) then tune to that number.

Okay well thanks everone for the info. Im gonna give the 1:1 ration a try. I guess i got some bad information when I was reading up on making them, or maybe did a horrible job at reading it.

anyone have any suggestions with tunning my ported sction.

winkychevelle
01-07-2014, 09:57 AM
there is so many variables really. A 1:1 ratio normally work well unless the woofer in question doesnt like seal boxes then I tend to go on the large side for the sealed like 1:1.15

But then you have subs that like sealed boxes. Then you can go larger with the ported side to gain efficiency.

Personally I never go past 2:1 ratios as the pass band is just way too narrow and I never push enough power to need that kind of box.

1/2 to 1/3cone area for port area tends to work well leaning towards the larger port.

passive radiators are not advised for this kind of box they will almost always be damaged.

last few boxes I built were tuned between 46-48hz tuning lower takes alot off the high end and pits it on the bottom end and vise versa

Jroo
01-07-2014, 11:55 AM
Did you have someone model these subs for you? I wouldnt just pick a ratio to start with because you may end up building a 4th several times to get it to sound right. All the ratios you see are in general and certain subs act differently depending on your goals. I have a 4th design for a Sundown sub that has a smaller ported section than the sealed side. When you look at the graph it is louder from 70 down than it was in the sealed or ported spec boxes but plays pretty flat. That would be a perfect example of somebody modeled it first and played with it real life before telling me what to build. A 4th order can sound good and get loud, or can sound like pooh if something is off.

4bannger
01-07-2014, 07:49 PM
there is so many variables really. A 1:1 ratio normally work well unless the woofer in question doesnt like seal boxes then I tend to go on the large side for the sealed like 1:1.15

But then you have subs that like sealed boxes. Then you can go larger with the ported side to gain efficiency.

Personally I never go past 2:1 ratios as the pass band is just way too narrow and I never push enough power to need that kind of box.

1/2 to 1/3cone area for port area tends to work well leaning towards the larger port.

passive radiators are not advised for this kind of box they will almost always be damaged.

last few boxes I built were tuned between 46-48hz tuning lower takes alot off the high end and pits it on the bottom end and vise versa

So it seems like im going to have to try find what works best for me. Ill try a 1:1 ratio. would it be advised that i make the sealed chamber like 1 or 2 cuft bigger than alpine reccomends

winkychevelle
01-07-2014, 09:58 PM
So it seems like im going to have to try find what works best for me. Ill try a 1:1 ratio. would it be advised that i make the sealed chamber like 1 or 2 cuft bigger than alpine reccomends

You dont want to go too big on sealed maybe 1.5times the rec but not 2times

SounDrive
01-07-2014, 11:42 PM
Tune the ported chamber to the sealed resonance.

Post the VAS and Fs (and recommended enclosure sizes) and I can give you some numbers to work with, I made a 4th order calculator of sorts for personal use.

You usually don't want to make the sealed size bigger than recommended unless the sub has a high Fs, because you'll drop your Fc really low and have a box with poor response on higher frequencies, and you may end up with a muddy response.

4bannger
01-08-2014, 08:53 PM
So after doing some research I found a resonance calculator online.

from the apline site
Optimal sealed: 1.75 cuft
Free air resonance (fs): 23hz
Equivalent stiffness (Vas): 100L (3.53 ftcu)


form the Speaker Box Calculations (http://www.bcae1.com/spboxad2.htm) that had the calculator
3db down point (f3): 36.2338 hz
resonant frequency (fc): 33.0752 hz
Enclosure volume (vb): 3.3053 ftcu

Can someone tell me if im on the right track here. From what yous said about tuning the ported to the sealed resonance i should tune my ported section to 33 hz?

SounDrive
01-09-2014, 04:36 AM
I would shrink it a little to try and get the Fc above 40..

4bannger
01-09-2014, 07:10 AM
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
01-09-2014, 08:51 PM
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
01-09-2014, 11:37 PM
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
01-10-2014, 03:56 AM
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
01-10-2014, 11:14 AM
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
01-10-2014, 06:57 PM
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
01-10-2014, 07:17 PM
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
01-10-2014, 09:27 PM
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
01-10-2014, 10:44 PM
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 :) 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
01-12-2014, 03:25 PM
im going to be posting up my deisned 4th order with an adjustable port on it.

4bannger
01-12-2014, 08:36 PM
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.

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SounDrive
01-12-2014, 10:02 PM
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.

265466142654661526546616

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
01-12-2014, 10:28 PM
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
01-12-2014, 11:12 PM
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 265466172654661826546619

SounDrive
01-13-2014, 03:04 PM
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 265466172654661826546619

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.

4bannger
01-13-2014, 04:30 PM
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.

Yes it would be I have a SUV and I took out my third row so I have Max room of like 47x50 I'm gonna revise the design one more time and put the adjustable port external and onto of the box to be more esthetically pleasing (well to my taste) and your right. It would be easier because changing the port length and volume would change the overall volume and effect my ratio and tuning if I'm right?

SounDrive
01-13-2014, 09:21 PM
Yes it would be I have a SUV and I took out my third row so I have Max room of like 47x50 I'm gonna revise the design one more time and put the adjustable port external and onto of the box to be more esthetically pleasing (well to my taste) and your right. It would be easier because changing the port length and volume would change the overall volume and effect my ratio and tuning if I'm right?

Yes that's correct. Having an external port makes sure that you won't be changing the volume.

4bannger
01-13-2014, 10:44 PM
Yes that's correct. Having an external port makes sure that you won't be changing the volume.

thanks learning a lot from you and all the other helpful people on this forum. I knew i could find someone knowledgable enough to help me with this. this is the final design here the tuning is the same, port size same except for length

SounDrive
01-14-2014, 06:59 PM
thanks learning a lot from you and all the other helpful people on this forum. I knew i could find someone knowledgable enough to help me with this. this is the final design here the tuning is the same, port size same except for length

Where will the port be firing? Towards the rear I'm assuming?

4bannger
01-14-2014, 07:55 PM
Where will the port be firing? Towards the rear I'm assuming?

firing up towards the headliner.

SounDrive
01-14-2014, 09:49 PM
firing up towards the headliner.

It may be louder with a surface to load off of. Port back (or on the side depending on the vehicle) usually works well.

T3mpest
01-14-2014, 09:58 PM
yeah I would NOT do port up in an SUV, especially in a 4th order. Many times upfiring causes nulls in upper bass response and that's really going to limit how high you sub will play if you have a sharp null like that, usually it's around 60hz. The low end tends to be better when you fire directly off the rear too, so you'd be screwing yourself on both fronts. My SUV is sub up port back right now, but since my subs can play upper bass no problem, I'll be doing sub back port back here very soon.

4bannger
01-15-2014, 06:31 AM
It may be louder with a surface to load off of. Port back (or on the side depending on the vehicle) usually works well.
well weather i was to fire it at the hatch door or at the roof i would have the same about of space between the port and door and roof


yeah I would NOT do port up in an SUV, especially in a 4th order. Many times upfiring causes nulls in upper bass response and that's really going to limit how high you sub will play if you have a sharp null like that, usually it's around 60hz. The low end tends to be better when you fire directly off the rear too, so you'd be screwing yourself on both fronts. My SUV is sub up port back right now, but since my subs can play upper bass no problem, I'll be doing sub back port back here very soon.

Yeah ill take some quick measurment and see whats up. Thanks for the suggestion. I knew that to be true subs but not ports.