Am I missing something

[Hooah87]

Hello everybody

I'm in the process of designing my first box and I've done a lot of research and I'm starting to input all the information to get my cut out sheet and I'm getting confused

My max outer dimensions are 38" width x 10" height x 13" deep. 3/4" mdf gives me 2.06 cubes

That was easy part. By the way my woofer is the re audio scx10d4v2 I'm powering it with a soundstream pn1.650d at 2 ohms

So When I type in my info on the12volt port calculator..

enclosure size 2.06, my port height 8.5" ,port width 2.5 inches and I want a tuning of 30 hz, says that my port length would be 27" .

So I then did 2.5 x 8.5 x 27 gives me 573.75

Then divide that by 1728 gives me 0.33 that's what my port displacement is correct?

Then I added 0.14 for my sub displacement to that, gives me total displacement for port and sub is 0.47.

So 2.06-0.47 = 1.59 cubes

So my box will be 1.59 cubes tuned to 30 hz correct

so I'm trying to input this info on winisd pro to see what the port velocity will be to see if it's a decent design and if this sub will do ok at this tuning frequency. Can anyone lend an opinion on how I'm doing so far

Thank you . Really appreciate your guys help

[Jessica]

your calculations for port displacement did not include port wall thickness from what i see. Not a big deal..

i get, using your numbers,

1.55 cuft net.

.37cuft port volume

13.71 sqin of port per cube

21.25sq inches of port

33.94 hz tuning

this assumes port and sub are on the same face and the port has 3 common walls and 3/4" thick wood.

i used torres calc. so you are probably somewhere between the two as far as tuning.

[Hooah87]

I knew I was forgetting something. And I was going to do sub facing up port firing towards rear of hatchback, it's a Nissan Cube I'm putting it in. Will that design change the tuning

[Jessica]

subs up doesnt change anything really. aside from how it will play in your vehicle. which i cant quantify as that would just require trying it to see how it performs versus other methods.

[Hooah87]

Ok sweet, thanks for your help, how would I go about checking if there will be any port noise based on that design l, do you know of a good program I could figure it out with.

[Jessica]

there is a use here, i can never remember their namem its like tricalculum algorythim or something. he know a lot about port velocities and things like that. he tends to post in a lot of these threads. i cant help you there but i can say too much port is not a bad thing. based on the rms of those sub, i think you are within the range you need though.

[Hooah87]

Ok cool thank you again. Maybe he'll chime in on it. If not I'm just gonna run with it. I'm gonna start tommorw on the build

[Hooah87]

I inputed everything on winisd and I came out with 27.840 m/s peak at 34.26 hz. That's the max port velocity out of every frequency. So I'm hoping that's a good number. I'm trying to find what number you want to stay under to avoid port noise

[DLHgn]

So here's what I got using WinIsd using

1.55 ft^3 net

33.94 Hz tuning

21.25 in^2 port area

and 650W of power

You'll get a peak velocity of ~27.6 m/s @ ~33Hz

You should be fine as far as compression and noise goes though it's still possible. You really want to keep the velocity below 30 m/s to help with these but even at 27 m/s it's still possible that you may hear something. To help ensure you won't you can employ round overs/flares to your port. You should be fine so long as you don't go past that much power. I say this because at 1000w RMS you will see a peak velocity of ~34 m/s. At that point you will probably be losing output due to port compression and could be hearing port noise.

[Hooah87]

Ok cool I'll do the round overs, from what I've read on earlier research before I started , my winisd graph shows that it will reach max excursion at 28hz and that it reaches -3db at around 27 hz. And that most of my graph is above the 0 db line . I like that it gets loud relatively low . But is it a box that is going to sound peaky beeteen 35 and 55 hz. Or is that a good thing, I listen to a lot of decaf and dj slow and throw so I was hoping it was tuned properly