Njord

I'm currently using a sealed box for my Alpine Type-R dimensions: 8.5x24x11 =1.3ft^3

I started playing around with this program that was recommend from this forum called WinISD, and this is what I came up with.





Text(inner dimensions):
Chamber Volume (ft^3) 1.3
Vent volume 0.0984
Sub volume 0.05
Total 1.448 ft^3
Cutoff Freq 32Hz
Vent Mach 0.11


Thinking about it now, I didn't take into account the displacement of the vent 'walls' (3/4 MDF) Besides that, any other problems? I'm hopping someone will let me know if this a good idea and how to make it better.

Thanks.

vrdublu

iTrader: (5)

Based on the Thiele small parameters you have there this sub should be incorporated into a sealed system, rather than a ported one. You have a huge hump at 60hz, I tried modeling this in Bass Box Pro and it didn't look so good, I also got the huge hump at 60hz but then it drastically fell off, this was modelled with 500wats inpitut. I recommend you go with a sealed box.

Njord

Bah, I'm using a sealed box now and the bass isn't satisfying. I thought the 'big hump' wouldn't be bad as I'm running this sub between 30-80hz. (30 being the minimum my deck/amp output)
Between 50-80hz there is only a 3db variance, but 4-7dBs higher then a sealed box.
Alpine recommends a small box for their subs.

vrdublu

iTrader: (5)

Satisying how? Doesn't play low enough=need better sub, perhaps a 12", isn't loud enough=need better sub or better amp. It is true that a box can solve some of these issues, but not all. I don't have all they specs of this sub so it's hard for me to help you. How much power you feeding it now, where is the box? In the trunk I presume? Detail helps sort out problems and more often then not, solves problems.

P.s: If you run a sealed box with a "Q" of 0.95 which is not ideal but............will give you 1.225 cu.ft after driver displacement but no bracing, so you would need to accomodate for that. That would give you an F3 of 39.1 hz, keeps your impedence nice and flat and your cone excursion never goes over 17-18mm which is what that driver is rated for anyway. Your response will be +1.67db at 70-80hz and drastically falling off past 200hz, fill the box heavily with poly-fill or equivalent and you're golden. This is all modeled on 500 watts with an output of 114.7db @ 66hz - 80hz.

stephenfleming

iTrader: (1)

I would recommend going with a larger box.
That will help level out that hump at 60hz, and probably move it down
Try the same thing, but make the box around 1.75 to start.
OR
Just build the spec box Alpine suggests

vrdublu

iTrader: (5)

Stephen stop wasting time on here and get my Tweeter pods done already, lol.

Njord

The sub doesn't sound that bad, but I feel like the small gains I could get from a ported enclosure would make it perfect. It just needs to go a little lower, and a little louder.

System info:
Type-R 10" 4Ohm DVC Powered by Alpine MRP-m500 500Wrms
Sub is in the trunk, firing forward (into cabin). The car is a small sedan(4dr)
Trunk lid and rear deck have B-quiet on it.


So you think with my current sub box, I should add poly-fill?
I just measured my box and its actually 24x7x12 = 1.167ft^3. Nothing fancy, no bracing (I don't think I need to worry about flexing at 500w)

Thanks for the help.

sunfired

iTrader: (-1)

Try turning it and firing it to the rear.

Denonite

iTrader: (1)

Sorry bro, I think there are some big problems with that. I'm not sure if I'm seeing that right, but those t/s parameters seem way off. I have the alpine manual with the t/s in front of me and it shows; vas 20 liters (250 l which i see there is 8.8 cubic feet...way too much for 10") , fs 33hz(reasonable for a 10", not 17.5 hz), spl 83 db(again reasonable, not 90), the rest seem ok. A little tip with winisd, don't put too much info in, just input fs, vas, qts, xmax, sd, pe, z(2, or 4 ohm won't change the graph, but you need something), check the auto calculate box and that's all you need for proper modeling. I assure you that your graph will be much nicer. Based on your info, I modeled your sealed in a 1.3 box, and a vented in a 1.3 (net) box. The good news is that it will deliver more output from 25 hz up to 100 hz, with approx 6 db more at 30 hz and 40hz, and 4 db better at 50 hz, max output is at 41 hz. There is no huge hump, but a nice smooth curve. Your box calculations are off as well. you need a 1.3 cube net inernal volume (1 cube works well...the Alpine box just so you're aware), but based on your box, the port needs to be 9.5" x 1.75" x 31" for a low vent velocity using a 25 hz high pass filter (subsonic) at any roll off rate even 6 db's works enough to reduce cone excursionbelow 18 mm. That ven will take up 0.43 cubic feet (includes wall thickness), and your sub has a displacement of .050 cubes, so a gross internal volume of 1.77 cubic feet is needed for that response. So, re calculate your box dimensions based on those numbers and you're set. Oh, and just so you know, I've been using Winisd for 5 years now and it hasn't let me down at all, every box I've designed works as expected.

MTA

iTrader: (1)

try reading the subwoofer hes using in the program.... its a 12 for starters and its not even an alpine... ACI SV12 ... does that clear up something?

seriously..with what your design is 1.3cu ft tuned at 32hz will play really nice... dont worry about what that program showed you... just build it and preferably use a 3" dia port about 9"( tunes at 36hz) and if I remember 12"long tunes around 32hz or so ,
just face the box backwards to let the port load...you will have nice lower extension and good kick
I did alot of alpine type r boxes..always 1.5 cu ft total tuned @ 32-36 hz
with a 500 watt amp this should play really good all day long

also change the shape of the box
12"x13.5"x22" works well for the 9" port...these are outside dimensions using 3/4" mdf