polk MM 10s ported, is this right?

[Cruzer 10+ year member]

here is what polk's website says for dual ported box.

Polk Audio - Car & Marine Audio Speakers

i type it in RE audio box calculator and it presents this:

is that right and i mount the subs side by side, to the right of the port.

or do i put the port in the middle, and instead of the L going all on 1 side, i split it and go half and half behind each sub?

Click to read more...

 

[Cruzer 10+ year member]

anyone? =/

 

[RAM_Designs 5,000+ posts]

Put the port on one side. With a skinny port like that, splitting it and making it even skinnier is only going to cause tuning problems.

 

[RAM_Designs 5,000+ posts]

I'm trying to figure out how they're getting their numbers. You have 12" deep inside the box, yet it's calling for the first port wall to be 10.75" long, and it can't be because the front piece that your subs will mount to calls to be 25.25", which will overlap the port wall...so first port wall should be 10" long to give you 2" of space from the back wall.

Also, with the second port wall being 18" long, you have 13.5"x2.75"x30" worth of port displacement inside the box(13.5"x2.75"x12" to the back of the box, then the 18" longer to the end of the port)...which is .644ft^3. Subtract that from the gross volume of 2.484ft^3, and you have 1.84ft^3...which is .12ft^3 smaller than what they say. And that's before sub displacement and any kind of bracing you may put in there. .1ft^3 for each sub and you're automatically down to 1.64ft^3 with a 34hz tuning. Put in a little bracing and you're looking at 1.55ft^3 or so tuned to 35hz.

I love proving how off the RE calc is...someone correct me if I'm missing something here and looking like a moron.

 

[SpeedEuphoria 10+ year member]

I love proving how off the RE calc is...someone correct me if I'm missing something here and looking like a moron.

The box is 28" wide so the 25.25" front + 2"port width +the side .75"= 28"

on the port wall 10.75" for the length is equal to the cut sheet 10" + the .75" for the front sheet

anyway the port displacement I get is also .644cubes. The internal volume total is 2.484375 -.644=1.84 cubes like you say before sub displacement and the higher tuning you say.

Anyway I think the OP is trying to build the box that it says on the Polk website. Pretty sure by comparing that you need to use 7.25" in RE calculator for the "square port length" as this 7.25" + the 10.75"=18" of port length which raises the box volume to near what it says on the polk website after displacement.

But the tuning will be higher like ~37-38hz or so as they are shallow subs but couldnt find displacement info in there pdf.

 

[Cruzer 10+ year member]

ya polk says for 2 10s make the internal volume 2.06 cubic feet. then i type it in RE calculator and it shows 1.945 or some crap.

im so lost and never built a ported box and seems this calculator is only confusing me more haha.

not to mention all this controversy and i havent even tried yet to change the dimensions and fit it in the spot i want...

so how do most people come up with their ported designs? or newer people, how do they do it?

also just to throw it out there, as i know nothing of how aero ports work, wouldnt an L shape port be less efficient as air has to travel around and out the port, as apposed to it being straight, or going through a aero port or regular tube port?

 

[SpeedEuphoria 10+ year member]

Basically you have to do pen and paper or calculator to verify or modify the design. You can use this to figure the tunning freq after you have correctly figures the volume subtracting the subs and port.

Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators

basically the aero's are more efficient so you need less port area, and also they take up less space then 3/4" mdf, so all in all you can make the box smaller using aero's

 

[SpeedEuphoria 10+ year member]

BTW this IS the Box I think? that Polk spec's for those subs:

See where I changed the port length total so it now equals the 18" that polk suggests, not the 32.5" like you had it. Crap they figure it off the back wall, which would make the tuning even higher and the box slightly bigger.

Not sure how polk wants you to do it. If like the RE calc your tuning will be more like 40hz

This would be with 18" port length as RE calc figures it.

If we knew the sub displacement then we would know which one is right, it may be the 2nd one, but thats kinda high tuning.

On another note, most here dont go exactly by the manufacturers specs. They go slightly bigger box and normally tune 30-35hz, maybe more for 10's? Also they use 12-16 square inches of port per cube(mostly 16). But most want to get Loud.

 

[Cruzer 10+ year member]

well i entered it how they had it on the website... 18 L u only put it at 7.25 where u got that idk...

Use 3/4" MDF for box building material. Slot port - 13.5 H x 2" W x 18" L

so they recommend tuning them to 36hz ??

 

[SpeedEuphoria 10+ year member]

the 18" length is the total length of the port

so the 10.75" and then the 7.25"=18" port length

but the re calc measures it off the back and side so it shows as 21.75" port length. If you cut that down like the 2nd pic so that RE calc shows 18" port length the tuning will be ~2hz higher or 38hz(then ~2hz more due to subs, read below)

They are recommending higher then 36hz as when you minus the subs displacement it makes the box smaller and the tuning higher by ~2hz.

So they are either recommending 38hz or 40hz depending on which way they measure the port length

 

[Cruzer 10+ year member]

well i really need my box to be 24 wide, by 21 or 21.5 deep. hight dont really matter as long as subs and ports fit.

can anyone help? prefer aero port but slot is fine, im not gonna be picky lol

 

[SpeedEuphoria 10+ year member]

I did some reading and the port length needs to be from the center of the port width so the RE calc is wrong and the volume is a little low compared to my math.

If you knew the displacement of your subs then I can prob make you a pic with correct info to your liking

 

[Cruzer 10+ year member]

so i should just not use the re calculator lol...

idk the displacement of my subs, nothing in manual or on website that i can find.

 

[Cruzer 10+ year member]

and using Products Menu i put 2.06 box @38hz port diameter 2, 2 ports, it says 5.22 length so where can i find 2 of them?

 

[RAM_Designs 5,000+ posts]

Two 2" circular ports isn't going to cut it...not even close.