newbie needs help with rlp 15 box - LONG

[2 lit jit 0]

alright, i ordered my rlp 15, dvc 4 ohm...def looking forward to it...its going to powered by a MTX 801D...800 rms, in a 5th gen civic coupe...i've build about a dozen boxes before but only done sealed...only lately i've been aquainted with winisd and other port determining programs...so i want to build my first ported box...

max outter lenght = 34.5" - pretty much written in stone

max outter height = 15.5" - pretty much written in stone

max outter width = up to 23 inches on bottom, 19 on top, this is a wedge box... - can be (shorter) smaller, not written in blood

max outside cube = 6.49 cubes

********|-----------\

sub is***|*********\

facing***|**********\

this side*|____________\

35^2 inch of port = (total height - 1.5) * (needed width) --> 35 = 14.0" * 2.5"

the main thing is i don't know how long the port is going to be...mike told me winisd does not do a good job with tc subs so i am kinda clueless about how long to make the port to get a tuning frequency of 28-32 with the net volume for the SUB to be 2.6 - 2.8 cubes...

although i can put up to a 6.5 outter dementions NOT net cube, i want some space for my junk too...that is why i really want to make the NET to be around 2.6 - 2.8, excluding the needed room for the port dispalcement and the room for the displacement of the wood..., if the total volume can be smaller, reduce the two width sizes with the top always 4 inches shorter than the bottom...I am also very curious about how this is going to work out with the WEDGE box on the back side...i don't know how the port is going to be effected if i need to extend the lenght to the back of the box...

i already posted a question in the unoffical forum but hopefully i get some answers here because of the traffic...

thanks!!!

i hope the answers i get here will help some poor soul too in the future too

[Supa_c 1]

www.psp-inc.com

you gonna need some 4" ports there pal

[2 lit jit 0]

so you're saying i can't use slotted ports?

anyways, from their port calculator and other port calculators, i'm "getting the idea" that port lenght is NOT going to dependant on what kind of sub it is but JUST the box volume and the port area...

is that right?

once again, i'm trying to get some answers because i do not want to base the specs on a program if programs can't read TC subs right...so as u can see, i am quite lost...

[mrray13 30]

ur correct in the assumption box volume and port area are the two most important aspects of box tuning. the sub is just need to determine it's displacement and to figure out what tuning is going to be needed.

with 800 wrms on tap, i'd run with the port area u have planed and use about a 2.5ft^3 box.

u can actually still run a slot port in one of two ways....

side load it and use a triangle port. i don't remember the formula to figure out triangle area, but all u have to do is keep the area about the same...

or still use an "L" shaped port, but the back wall will have to be two walls.....kinda like this..

*= the outside of ur box and looking at it from the top

*****************----------- 

[Nikuk 1]

the woofer in question does interact with proper vent design.

Any given 1.0 cu ft box with a 2" pvc port would be alright for a 12" woofer with 3mm of xmax and a looser suspension.

But if you were to drop in a 12" woofer with 25mm of xmax & a stiffer suspension, you are going to have much more of a back wave, output, displacement.

Suddenly, the vent mach just went way the hell up.

[2 lit jit 0]

thank you mrray13, i appreciate your help...i think i will go with your first idea of making the port on the back of the box into a wedge shape port with the total area of that side equal to the area of the square port on the front of the box...

because the square port is going to be:

35^2 inch of port = (total height - 1.5) * (needed width) --> 35 = 14.0" * 2.5" (front regular port sides on side of box)

the wedge area will be:

height = 14, triangle base = 4 inches

x = 4 * .5 * 14 = 28^2 inches of area, NEED 7 more square inches

7 = x * 14 --> = x = 7 / 14 --> x = .5

so i will need a port of .5" x 14(height) and a triangle port of 14" x 4"

i'm thinking of putting a glass top on so i think this will be cleaner than your second idea...on second thought, i might do your second idea if no glass top...

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|*|**\

|*|***\

|*|****\

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.5", 4" (height is 14", side view)

ohhh, i hope this works!! thanks for the idea mrray!!!

anyways, NOW how do i figure out the LENGHT now????

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* xxxxxxxxx | * *

* xxxxxxxxxxx*x*

* xxxxxxxxxxx*x*

* xxxxxxxxxxx*x*

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by the way, just to double check, all the X's would be my NET displacement EXCLUDING the displacement of the sub right?

[Supa_c 1]

so you're saying i can't use slotted ports? 

anyways, from their port calculator and other port calculators, i'm "getting the idea" that port lenght is NOT going to dependant on what kind of sub it is but JUST the box volume and the port area...

is that right?

once again, i'm trying to get some answers because i do not want to base the specs on a program if programs can't read TC subs right...so as u can see, i am quite lost...

<{POST_SNAPBACK}>

i made a wedge ported, you have to use round ports.

unless....you make the port under the woofer, i dunno about that one

[2 lit jit 0]

i made a wedge ported, you have to use round ports.

unless....you make the port under the woofer, i dunno about that one

so you're saying that mrray13's 2 technique will not work? they are perfectly sound to me...please tell me why they won't work...for my sake and every else wondering...

i would love to figure out a way to do a bottom port but the lenght to height ratio would not be good...it would be something like 35:1 instead of 8:1

anyways, anyone know how i can figure out the lenght of the port specificly to the rlp's? mike? help

[mrray13 30]

the woofer in question does interact with proper vent design.

Any given 1.0 cu ft box with a 2" pvc port would be alright for a 12" woofer with 3mm of xmax and a looser suspension.

But if you were to drop in a 12" woofer with 25mm of xmax & a stiffer suspension, you are going to have much more of a back wave, output, displacement.

Suddenly, the vent mach just went way the hell up.

u are correct, i forget to mention how the sub's xmax helps to dtermine port area..

2 lit...carstereo.com has a great port calculator...u plug in net box volume, port area and desired tuning..it gives u length...i know of two local shops who use it to figure ports

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[2 lit jit 0]

thank you mrray13,

this is the info i plugged in for SIZE of port:

Driver Size: 15

Num of Driver: 1

Enter Xmax: 24.6

Tuning Freq: 28.5

This is the output:

Min diameter: 9.64" (round port)

Min Area : 72.97^2 inches (WTF)

Lenght side : 8.54 inches (for square ports)

Info plugged in for LENGHT of port:

Quantity of Ports: 1

Volume of Enclosure: 2.6 (I wasn't 100% if this is net)

Height of Port: 14

Lenght of port: 5.2121 (72.97/14 = 5.2121)

Output:

Vent lenght: 83.46 inches long

QESTIONS:

1.) This was not the result i was hoping to hear from the calculator...why does mike recommend 35^2 inches of port when the calculator ask for 73^2 inches?

IF i plug in all the same up there with the exception of the lenght to be 2.5 instead of 5.2121 (to get only 35^2 inches of port),

the lenght came down to: 38.53"

so whats the deal?

hope i'm not asking too much questions just want to do it RIGHT

[Nikuk 1]

Without having gone to that link myself....

I'm assuming that that calculator is assuming full ouput at tuning. Vent speed will be highest at tuning. However, you will NEVER reach full xmax at tuning with that woofer.

The woofer become it's MOST efficient at tuning, moving very little air but with alot of output (if that makes sense). Debunking that calculator.

I doubt that you need 28in^2 of port per ft^3. Not with that woofer at it's Pe.

[Nikuk 1]

oh, duh:

If SoundSplinter recommends 13.5 in^3 per cube... go with that. Unless you have your own program to estimate NFR graphs & vent property graphs.

[2 lit jit 0]

I'm assuming that that calculator is assuming full ouput at tuning. Vent speed will be highest at tuning. However, you will NEVER reach full xmax at tuning with that woofer.

The woofer become it's MOST efficient at tuning, moving very little air but with alot of output (if that makes sense). Debunking that calculator.

I doubt that you need 28in^2 of port per ft^3. Not with that woofer at it's Pe.

i didn't get what u were saying in the second paragraph...probably because i'm still a newb at this whole port thing...the only thing i think i got is that i will not need that much port area...

If SoundSplinter recommends 13.5 in^3 per cube... go with that. Unless you have your own program to estimate NFR graphs & vent property graphs.

so basicly GO with the SS specs and give it 35 cube inch of port and get a lenght of 38.5 inches...???

i would really like mike to confirm all this so it can help me and others out before i built it...i assume mike is busy but i'm not in a hurry anyways...won't get my sub for another week and probably won't built it till spring break anyways...

*Pulls out HAIR* all this time i thought that you plug in A, B, C, D and you should get a straight answer E...looks like it seem that theres more to it...the only problem is that it seems like everything is not as strutured as i thought it did...meaning that i hope all this is STILL not just some hit and miss in the dark

[mrray13 30]

like nick said, go with SS's recommendations...i don't ever use the port area calculator...and now u know why..lol..

i'd do the 35in^2 of port and whatever length the port calculator gave u...

the thing to remember, the calculator does not account for sub or port displacement meaning, when u build ur box, u have to manually account for them and build ur box accordingly to achieve the net volume of 2.6ft^3 after port and sub displacement...

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[SoundSplinter 1]

Hey 2 lit jit...

Sorry for leavin' ya hangin', been a whirlwind 'round here tryin' to catch up after my much enjoyed vacation in New York

To put your mind at ease, you will not need more than 35 sq inches of port area for that baby to sound great, but on the same token the 35 sq inches is a minimum value recommendation. You can always use more if you have the space and drive to do so but in short, 35 sq in will work very well for the RL-p15's job.

[2 lit jit 0]

the thing to remember, the calculator does not account for sub or port displacement meaning, when u build ur box, u have to manually account for them and build ur box accordingly to achieve the net volume of 2.6ft^3 after port and sub displacement...

i think i can mange that bro...thanks...i'll get everything planned out and def let everyone have a look at it...

Hey 2 lit jit...

Sorry for leavin' ya hangin', been a whirlwind 'round here tryin' to catch up after my much enjoyed vacation in New York

To put your mind at ease, you will not need more than 35 sq inches of port area for that baby to sound great, but on the same token the 35 sq inches is a minimum value recommendation. You can always use more if you have the space and drive to do so but in short, 35 sq in will work very well for the RL-p15's job.

no problem mike...i know you're having fun, and like i said, i'm Definitely not in a hurry...

i'm tell ya, i'm learning alot from doing all this asking...hope you get my letter soon and in the mean time, i will be planning my box...

thanks

[2 lit jit 0]

just to give the updates:

mike says she's on her way :D:D

anyways, i did some more searching and putzing around...seems like the online calc mrray gave me and winisd is VERY VERY close to each other...so i'm assuming its going to be correct...

i put in same amounts for each one and i got very close figures...all in inches!

2.5 Cubes

Tune: 28hz Winisd = 41.14 OnlineCalc = 41.99

Tune: 30hz Winisd = 35.06 OnlineCalc = 35.79

Tune: 32hz Winisd = 30.08 OnlineCalc = 30.71

2.6 Cubes

Tune: 28hz Winisd = 39.33 OnlineCalc = 40.14

Tune: 30hz Winisd = 33.48 OnlineCalc = 34.18

Tune: 32hz Winisd = 28.69 OnlineCalc = 29.29

2.7 Cubes

Tune: 28hz Winisd = 37.65 OnlineCalc = 38.43

Tune: 30hz Winisd = 32.02 OnlineCalc = 32.68

Tune: 32hz Winisd = 27.98 OnlineCalc = 27.98

2.8 Cubes

Tune: 28hz Winisd = 36.09 OnlineCalc = 36.83

Tune: 30hz Winisd = 30.66 OnlineCalc = 31.30

Tune: 32hz Winisd = 26.21 OnlineCalc = 26.76

looks like u can't go wrong with either one...

So since i am going to try to get a 2.5 cube box, which one should i tune it to? give me a suggestion...thanks

[mrray13 30]

32-34hz is plenty low enough...

i like 34 hz for 15's...but that's my opinion....

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee