Box tuning?

I know this question has been asked before but I'm looking for a website that gives accurate port dimensions. Also, how to you measure the port? LxWxH? I need to figure out the port dimensions for 31Hz in ~8 cubes. Width is about 37", height is about 17", and depth about 26". It's about half MDF and half glass so figuring out the exact volume is difficult since the box cannot come out of the car. Thanks for any help.

I found a page on caraudio.com. I hope its accurate.

WinISD is as actuate as you will need.

8 cubes net after all displacements including driver and port? If so go as follows.

6 3" ports 12.6" long each
8 3" ports 17.5" long each
10 3" ports 22.5" long each
12 3" ports 27.4" long each
4 4" ports 14.6" long each
6 4" ports 23.4" long each
8 4" ports 32.2" long each
10 4" ports 41.0" long each

Where did that info come from? Also, how about slot ports. A single 16" x 4". What would the depth be for 31 Hz for 7, 7.5, and 8 cubes, excluding driver and port displacement (exact volume is still undetermined)?

make that 15 inch tall x 4 inch wide

8 cubes net after all displacements including driver and port? If so go as follows.

6 3" ports 12.6" long each
8 3" ports 17.5" long each
10 3" ports 22.5" long each
12 3" ports 27.4" long each
4 4" ports 14.6" long each
6 4" ports 23.4" long each
8 4" ports 32.2" long each
10 4" ports 41.0" long each


Also, I'm not sure I understand how you did this figuring in port displacement. Let's say my box is 7.5 cubes. The driver displacement is .36 cubes. So I'm at 7.14 cubes. To tune a 7.14 cube box to 31 Hz requires a certain size port. So I use 7.14 cube port dimensions. If port displacement needs to be accounted for, my 31 Hz port has changed my box from 7.14 cubes to roughly 6.5 cubes. Since the enclosure is smaller due to displacement, the port size is now not correct because it was calculated based on a 7.14 cube box. Should I just assume that the box will be roughly 6.5 cubes with port and driver displacement and port based on that volume? If I tune based on 7.14 but port displacement makes it ~6.5 then my tuning freq changes from 31 Hz to about 29.6 Hz. How much would 1.4 Hz change the sound? And does this post make sense? Sorry if it doesn't.

somebody plz help quickly, i have to get these dimesions tonite. ng, fry, stang, where ya at?

things have changed, its actually 6.64 cubes without displacement so ill have to figure that out. should i tune higher to make up for lack of volume or staple cotton to the inside of the box?

well, the decision was made. since the subs are only 2 inches apart and there isn't much room above or beneath them, a slot port was pretty much ruled out. my favorite next to the slot was 6 3 inch ports 16.74 inches deep. three on top and bottom in a triangle patter low and upside down triangle high. the other option, to reduce port displacement as much as possible is two 4 inch ports, 8.3 inches deep or even 2 3.5 inch ports 6.03 inches deep. they seem awful small but i guess that is how it works.

COMPLETELY stuff that bitch with as much polyfill as you can get in it without Blocking the polevents and ports to get them up closer to 8 cubes NET.

doesnt work that way with ported enclsoures.

So are you saying polyfill doesn't work in ported boxes CB?

yes it does dipshit. It slows down the waves hence making the box sem bigger. My AV18's box changed when I just lined it with polyfill. It makes the box seem bigger, lowers the tuning, and helps the low end out a little bit.

does it matter how large the port is as long as it is still the right tuning freq? what i mean is, a 6 inch long port seems awfully small will it still work the same as a larger port of the same freq?

You do want to have a certain amont of port area so that it doesn't make wind noises and so that there's atually the area there to properly handle the sound waves, but no as large as the tuning is correct don't worry about a short port.

Who's a Dipshit bumpinstang77?

All polyfill does in ported boxes is slow air flow clogging the port. Go ahead and do it and you'll feel kinda stupid when a nice hunk of it goes flying out of oyur port because its been clogging it up.

will there be a large difference in sound from 3 cubes per speaker and 3.5 cubes per speaker at 31 Hz?

also, what if i wrap the polyfill loosely in some kind of fishnet to keep it away from the pole and the port? like a big loose block of it.

if you where going to put polyfill in there i would reccomend you get the quilt lineing stuff instead and stple ot to the whalls, a few layres. the difference between 3 and 3.5 is 100% dependant on the speaker. you'll loose some flatness and possibly a decible or so but nothing too drastic.

All polyfill does in ported boxes is slow air flow clogging the port. Go ahead and do it and you'll feel kinda stupid when a nice hunk of it goes flying out of oyur port because its been clogging it up.

So the port acts kinda like a small fan ? I wonder where all the air comes from .........

CB Is the dipshit......... And yea Germany something like that to block it all off is good...... Everyone check this out.

http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic&f=11&t=076651#000000

OMG!!!

Reat u on how hemholtz resonators work, why fiberfill is used in enclosures, and why ported enclsorues work Bumpin.

The driver presurizes the enclosure, the air goes to escape through the port, the driver causes a vacume, the air is pulled back in... IF some is to come loose and block the flow of air you are loosing SPL and chaging tuning by slowing down the pressur chages.

Wow, slowing down pressure changes, maybe that is why fiebrfill is used in Transmission line and 1/4 wavelength enclosures?

I like how everyone explains it as "tricking" the driver. Sure is cool to know my ava 18 has studied southpark and is all like "what ever, whatever, ill do what i want" Reguardless of what the amp is telling it to do and the only way to get it to do what you want is to feed it chicken skin (fiberfill).

Im not debating that you cna change how the driver acts with the enclosure, im saying it isnt a good idea. The ONLY time i ressomend putting anything in your enclosure is opencelled foam in enclosures large enough to have Nodes or antinodes. the link you posted stated itsself, 40% is the maximum you can gain...and that is by stuffing it to the hilt. what does that do? slow pressure changes and therefor tuning, even with the new "net" airspace.

Not only do you change tuning you will loose potential SPL. i doubt the difference between 3 and 3.5cuft with an SX is going to be drastic. a little bit more peaky, maybe an extra 1-2dB more peaky.

thanks for all the help. one more quick question, should i now refigure the port size for what the box will seem to be with poly in it? or is ok to leave it? i believe that leaving the same size will cause it to be tuned lower after adding poly to it so wouldnt that make up for the slight loss in low end due to the box still being just under 4 cubes per sub? i know 3.5 is nominal so should i concern myself with trying to make up for it at all?

OMG!!!

Reat u on how hemholtz resonators work, why fiberfill is used in enclosures, and why ported enclsorues work Bumpin.

Trust me I know more about this shit then you ever will.

The driver presurizes the enclosure, the air goes to escape through the port, the driver causes a vacume, the air is pulled back in... IF some is to come loose and block the flow of air you are loosing SPL and chaging tuning by slowing down the pressur chages.

LOL!!! Poly fill doesn't block AIR It slows down waves and moke the air seem bigger. Quit talking out your ass and look at the test. Always tryin to sound smart.

Wow, slowing down pressure changes, maybe that is why fiebrfill is used in Transmission line and 1/4 wavelength enclosures?

I like how everyone explains it as "tricking" the driver. Sure is cool to know my ava 18 has studied southpark and is all like "what ever, whatever, ill do what i want" Reguardless of what the amp is telling it to do and the only way to get it to do what you want is to feed it chicken skin (fiberfill).

Once again you need to pull your b/fs dick out of your mouth and talk some sense.

Im not debating that you cna change how the driver acts with the enclosure, im saying it isnt a good idea. The ONLY time i ressomend putting anything in your enclosure is opencelled foam in enclosures large enough to have Nodes or antinodes. the link you posted stated itsself, 40% is the maximum you can gain...and that is by stuffing it to the hilt. what does that do? slow pressure changes and therefor tuning, even with the new "net" airspace.

Do you just like randomly make shit up as you go on. Like your own little fake Audio Physics????

Not only do you change tuning you will loose potential SPL. i doubt the difference between 3 and 3.5cuft with an SX is going to be drastic. a little bit more peaky, maybe an extra 1-2dB more peaky.

Yea you tune it a little lower. You do loose a little SPL in the top end to gain some low end and a better all around sound. And the difference isn't drastic but its a decent change for the better.

so i should leave the port the way it is or reconfigure it for how the polyfill affects it? i still want to hit high numbers. if i dont hit at least 150 im gonna have a damn stroke. i could have just bought two si mag 12s and been able to build the absolute perfect enclosure instead. these SXs better impress me after all the stress im goin through with the install, not to mention all the time ive waited to do this.

bumpin' im not going to sit here and aregue with you, im areguing with a wall. Germany, do what you want. I gave my advice so take it how you want.

i cant stand it when a thread turns to arguement. cb, i appreciate your advice and value it but i want to get several opinions. i know both you and bumpin are knowlegable and want ideas from both of you. i think im gonna poly the shit out of the box and tune to match it. if it doesn't change much of the volume of the box then it still shouldn't change tuning much. thanks for everyones help.

alright, ive been fucking around with winisd and i cant figure it out. there isn't a listing for the re sx. everything else is there but re. when i enter info for a new driver it tells me there is something wrong with qes, mms, etc. where can i get more on the ts parameters. the website asks for more info than reaudio.com lists. someone help me out please.

CB's just to young to comprehend. He hasn't experienced enough, and hasn't had any college level Physics classes.

n00bx.

nG

I know what happened with a number of enclouses which we stuffed that where ported.

and you have to enter the SX's T/S params into WinISD.

and you have to enter the SX's T/S params into WinISD.

WinISD means jack shit to me.

nG

as does me, but he asked why the SX, and other RE speakers, arent in WinISD.

Only thing i use winISD for is Ports and transient responce.

I guess I am glad I just build a sealed box and I'm done with it.

ive decided to place the ports on the back of the box between the seats. only problem is they cant be longer than 10 inches. so looks like im working with six 2 inch ports. i wanted to go with more port displacement but i guess its all i can do. even so. six 2 inch ports is still a good amount of port displacement. the box came out to 3.5 cubes per speaker net with a little poly fil i will be looking good. i pick it up saturday so pics will be up on sunday. id do it sat but im gonna be in my car all day and night. so sunday while im on duty and cant leave the ship ill post lots of pics.

6 2" ports? WTF? that is only 18sqin of port area.

i hope you ment 2 6" ports.

i was able to work a 5 1/2 inch port 10.9 inches long. it tunes to 35 hz but im gonna drop a lot of poly in it to drop the tuning a little.