4th order design 2 alpine type r 15's

[4bannger 10+ year member]

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

View attachment 26546486View attachment 26546485View attachment 26546484

Click to read more...

 

[4bannger 10+ year member]

come on 15 views and no help

 

[RangerDangerV2 5,000+ posts]

I like 4th orders.

 

[4bannger 10+ year member]

I like 4th orders.

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

 

[SounDrive Pro Seller]

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 10+ year member]

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 Pro Seller]

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 10+ year member]

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 10+ year member]

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 10+ year member]

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 10+ year member]

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 10+ year member]

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 Pro Seller]

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 10+ year member]

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 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 Pro Seller]

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