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View Full Version : Re-tuning a box with slot port *pic*



Xprime4
05-19-2009, 08:47 AM
I installed the box in my car few days ago and i'm not too sure i love the sound of my sd2.5. They were hitting much clearer and less boomy in a similar ported box with a smaller port area. They now don't sound flat but are def louder.

The box is ported 7.2 after subs but before port displacement. tuned around 37 in a slot (wall going in.. that's it) box. Anything i could do (now that the box has been glue and carpeted) to change my tuning? I was thinking about sealing the slot (there would still be a mdf sheet getting in, but seal) and adding a 8inch sonotube (50ish in/sq round compare to my actual 131 square). Any other idea?

little picture of the box. I won't be building another one since i'm broke :greedy:
http://i371.photobucket.com/albums/oo152/xprime4/box9.jpg?t=1242737201

Xprime4
05-19-2009, 08:53 AM
now that i think about it, there won't be space for the tube because the port will be in the way :eek: What to do?

Xprime4
05-19-2009, 12:01 PM
I just checked some more calculator and if i want to add a 8inch sono, it only got to be 9-10 inch long for a 34-36 hz tuning with 7.3ft/cu? accurate or not? that sound like a small port to me

mlstrass
05-19-2009, 12:17 PM
what is the NET enclosure size? Seems like a lot of port area, like over 20^2 per cube which is pretty high for a daily box.

And "assuming" those are 15's then your box is WAY too small. I'd want at least 3.75cubes NET per sub with 4 - 4.25 per sub even better with 16^2 of port per cube tuned at 38Hz.

mlstrass
05-19-2009, 12:19 PM
You could try laying MDF in the port to take up port area, but you'll also lower tuning some. That would at least give you an idea if the port is the issue.

I ran a DD 9515 in 4cubes with 80^2 of port area and tuned to 42Hz and it actually sounded pretty good on all types of music.

Xprime4
05-19-2009, 12:30 PM
Yeah the box is on the low side, but the last one i had was too , yet still sounding a lot better to me...
Like i said, box is 7.2 after sub displacement. The port atm 17height 6.75 wide.
From my calculs, that gives 114.75 then divide by 7.3 ( or is it after port displacement???) = on the 16ish per ft/cu... my last one was more like 12-13 , yet sounding a lot sharp and better transitient response on fast kick bass

also the idea of trowing mdf in it... how do i do that? cut smaller and silicone ? i'm not sure this would be easy

jmanpc
05-19-2009, 12:34 PM
slide a piece of wood in the same height and length as the port and glue it up against one of the walls. it will make the port 3/4" narrower. repeat if necessary.

Xprime4
05-19-2009, 12:37 PM
slide a piece of wood in the same height and length as the port and glue it up against one of the walls. it will make the port 3/4" narrower. repeat if necessary.

well sound simple by the way you say it. I may try that.

What about the sono? 8inch diameter x 9-10 inch long and sealing the port (the airspace won't be lost that way right?)

also, if I take jmanpc idea, this will higher the tuning not lowering it? It's ok for my if it's lowered... not sure about getting it even higher

mazdakid
05-19-2009, 01:11 PM
Putting a piece of mdf in there will lower the tuning. If you're going with a sono, just get a 10". Id use the old slot as a brace and cut windows out of it.

Xprime4
05-19-2009, 01:14 PM
Putting a piece of mdf in there will lower the tuning. If you're going with a sono, just get a 10". Id use the old slot as a brace and cut windows out of it.

all i got is a jumping saw and no talent using it:rolleyes: a 10inch sono would need to be longer than the 8inch one right?

mazdakid
05-19-2009, 01:27 PM
A 10" needs to be longer than an 8" to be tuned the same. The sono will take up less airspace too

Xprime4
05-19-2009, 01:48 PM
so my 9.5-10inch with a 8inch sono for 34-35hz sound accurate? i wouldn't too much job to do if that sound cool. I love sono ;) and smaller port area = less peaky sound right?

Xprime4
06-16-2009, 11:54 AM
I'm bumping this coz i want some more change

I was thinkign about sealing the port... and putting a 8 inch sono facing the box top. Box pic is in signature

There won't be as much clearance between the port and the hatch. But i'd like to experiment. Would it works? The 8 inch sono would be 10 inch long for a 36hz tuning.



http://i371.photobucket.com/albums/oo152/xprime4/artskill.jpg?t=1245168037

Xprime4
06-16-2009, 12:09 PM
sry if the draws aren't clear.

The first one is box top
Second one is side view... with the hatch closed (showing the clearance)

I know the port area is small, but i like the sharpiness of smaller port area

maybe that pics would be more representative
http://i371.photobucket.com/albums/oo152/xprime4/box12.jpg?t=1245168766

DonH
06-16-2009, 12:51 PM
jesus man just re do the box bro! no money? just go **** sum fat chix for sum $$!

re do the box with the 8" sonotube with the length at ~9.5" or so for a 35hz tuning

make sure that the tube has at least 8" behind the end of the port though bro!!

Xprime4
06-16-2009, 12:55 PM
jesus man just re do the box bro! no money? just go **** sum fat chix for sum $$!

re do the box with the 8" sonotube with the length at ~9.5" or so for a 35hz tuning

make sure that the tube has at least 8" behind the end of the port though bro!!

I'm just tired of buiding boxes... i've just build one for a car that i sold 1month later, now i did this one a month ago and... 100$ worth of stuff each time... that's enough !!!

I'll probably be switching sub again in few months anyway :laugh:

8 inch of clearance? that's gonna be difficult. Is it really THAT important?

Xprime4
06-16-2009, 10:47 PM
lil bump for tonight. Is it worth it to try my new design or not, if i can only get like 4 inch of clearance outside of the port

mbrooky
06-18-2009, 01:23 AM
Yeah the box is on the low side, but the last one i had was too , yet still sounding a lot better to me...
Like i said, box is 7.2 after sub displacement. The port atm 17height 6.75 wide.
From my calculs, that gives 114.75 then divide by 7.3 ( or is it after port displacement???) = on the 16ish per ft/cu... my last one was more like 12-13 , yet sounding a lot sharp and better transitient response on fast kick bass

also the idea of trowing mdf in it... how do i do that? cut smaller and silicone ? i'm not sure this would be easy



well if it's 7.2 cuft before port displacement then with port displacement @ 37hz that only gives you roughly 5 cuft for both subs to share.....you could always build a square port like this....(i'm in the same dilemma sorta...probably gonna go 8" sonotube or square port like pictured cuz the slot port takes up too much volume)

mbrooky
06-18-2009, 01:26 AM
oops here's the pic i was talkin about....

http://www.caraudio.com/forum/attachment.php?attachmentid=26512096&d=1245298011

spl_robb
06-18-2009, 05:05 AM
you can use mbrooky idea, and do a removable port like i did.(sub up-port back) that way you dont need to re do a box. just play with dif. port lenghts and diameters.just try to do long port so you can cut to yor fs needs.

http://i182.photobucket.com/albums/x45/drift_robb/DSC00705-1.jpg

Xprime4
06-18-2009, 10:52 AM
So i did some mods to my box yesturday and had few listening hours already.

Sub up , 8inch sonotube up... around 6 inch of clearance before the window.

Result: -On some songs, the bass def hit harder than with the port on rear side.
-Tuned around 37hz killed some lowest line (34hz before), but the upper roll
seems higher. Still some hard flexing lows. I guess its from getting some more
airspace. The 8inch sono take very little compared to the port i had (i destroyed it
with an hammer and sealed the port hole.

And finaly, i'm getting some port noise on some tracks i didn't before (white girl).. a little annoying. I put the ssf from 15hz to low 20ish and it help a little
Definitively more rearview mirror movement now too...


So i think the operation went well. On a bad note, I destroyed most of the bracing by destroying the port. The box is flexing a little, but no air leak.Sounding better to me.

Any bracing i could add one the box is sealed? And i'm looking at 10inch sono... but i don't want the bass to be too boomy

Xprime4
06-18-2009, 10:55 AM
you can use mbrooky idea, and do a removable port like i did.(sub up-port back) that way you dont need to re do a box. just play with dif. port lenghts and diameters.just try to do long port so you can cut to yor fs needs.

http://i182.photobucket.com/albums/x45/drift_robb/DSC00705-1.jpg

Great. Aeros are great for that too. If i'm not fully satisfied with the tuning. just put another lenght or cut and you got a new box :cool:

That box already went through 3 operations and still alive

spl_robb
06-19-2009, 03:21 AM
So i did some mods to my box yesturday and had few listening hours already.

Sub up , 8inch sonotube up... around 6 inch of clearance before the window.

Result: -On some songs, the bass def hit harder than with the port on rear side.
-Tuned around 37hz killed some lowest line (34hz before), but the upper roll
seems higher. Still some hard flexing lows. I guess its from getting some more
airspace. The 8inch sono take very little compared to the port i had (i destroyed it
with an hammer and sealed the port hole.

And finaly, i'm getting some port noise on some tracks i didn't before (white girl).. a little annoying. I put the ssf from 15hz to low 20ish and it help a little
Definitively more rearview mirror movement now too...


So i think the operation went well. On a bad note, I destroyed most of the bracing by destroying the port. The box is flexing a little, but no air leak.Sounding better to me.

Any bracing i could add one the box is sealed? And i'm looking at 10inch sono... but i don't want the bass to be too boomy

any pictures on the new box??

Xprime4
06-19-2009, 10:03 AM
any pictures on the new box??

Got a video of it . It's not pretty btw... still need some more painting job on the port area.

http://s371.photobucket.com/albums/oo152/xprime4/?action=view&current=HPIM2530.flv

The total lack of bracing ain't great. Anything i could add now to make the box more solid?

Lakota
06-19-2009, 10:22 AM
Aero port.

Xprime4
06-19-2009, 10:26 AM
Aero port.

yeah that's what it is, now...

Lakota
06-19-2009, 10:35 AM
Needs "flare."

Xprime4
06-19-2009, 10:37 AM
Needs "flare."

how would you flare a sonotube?

krainium
06-19-2009, 10:46 AM
You could add threaded rod or wooden dowels to the inside to stiffen it up. To add flare to the sano tube you have to make a piece of mdf that is flared then add it to the end of the sano tube.

Xprime4
06-19-2009, 11:08 AM
You could add threaded rod or wooden dowels to the inside to stiffen it up. To add flare to the sano tube you have to make a piece of mdf that is flared then add it to the end of the sano tube.

Getting the bracing inside, once the box has every side on ain't easy... i have no skill and no equipment beside a jigsaw... any pics or dyi of the process of turning a sono into a flare sono

krainium
06-19-2009, 11:12 AM
Building a flare is out of the question unless you have a router. You should be able to slide a wooden dowel or threaded rod thru the sub hole by the looks of it.

Lakota
06-19-2009, 11:34 AM
Cut out different size mdf rings and stack them together. Fill in the gaps with fiberglass.

Lakota
06-19-2009, 11:36 AM
I would add threaded rod to the plane that has the sub on it. Those pieces of mdf that you had it there are not very stiff.

Xprime4
06-19-2009, 11:38 AM
I would add threaded rod to the plane that has the sub on it. Those pieces of mdf that you had it there are not very stiff.

ok i'll check that.