DiyMobileAudio.com Car Stereo Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter · #1 ·
Greetings Everyone, New member here to diymobileaudio and car audio so please bear with me. So with that being said hope you guys can help me out!

I plan on building a ported enclosure for my suv trunk less(all open).I've started with the build on winisd and I feel like I'm halfway there. I just need clarification and additional advice to continue on.

The internal Net volume is 6.45³
with bracing displacements and speaker displacement. The volume drops down to 6.26³

This is the figure I inputted into Winisd 6.26³(after displacements not including port yet) so now Winisd can give me the port size and after playing around. I take note of the port dimensions I end up with (3.5x16.5x25.30)
I factor in the(.75mdf) just a rough draft no drawings yet. Ends up at (4.25×16.5×25.30) which the port is 1.03³

At this point now I Subtract the 6.26³(Displacements not including port) from the port displacement which is (1.03). It puts me at 5.23³.


I used the 6.26³ to get my port size to see the air velocity performance before the port is factored in.

I used the 5.23³ for winisd to see the transfer function, SPL, and cone excursion.
Now I would assume my internal airspace is 5.23³(all displacements added in) and that's how much the room the sub has to breathe

In summary I calculated net volume
subtracted the displacements not including port, inputted that volume in Winisd to get my port velocity only and subtracted the port from the volume again to get the airspace.

I added pictures and the port velocity has a different volume before I subtracted.

Did I do this right or completely wrong? I hope not if I did I'm willing to scrap my plans and start over. Thanks guys for your help!
Rectangle Slope Plot Font Parallel
Slope Rectangle Plot Font Parallel


Rectangle Slope Plot Font Parallel
Rectangle Slope Plot Font Parallel
Rectangle Slope Plot Font Parallel
 

·
Registered
Joined
·
1,386 Posts
Well its probably ok but you didn't list the model of the sub so how could anyone check?

the volume you put into winISD is the net volume of your design. You dont put in 6.xxx and then figure out tuning and then change the volume again.. You have to consider both at the same time or iterate back and forth to arrive at the correct net volume corresponding to a gross volume available.

The port velocity plot has the wrong volume so that might be wrong.

The tuning freq seems pretty low, why did you pick that?

how much power are you running?
 

·
Registered
Joined
·
2,256 Posts
software operate with net volume, so if you want to end up with let say 5cuft you will have to add to this volume all sub volumes like port, brace and speaker displacement.

Old Speakershop software was so easy and clear on that, but it only operate on very old win platforms like Win97 or 2000, lol
 

·
Registered
Joined
·
382 Posts
Just cut off the speaker displacement volume and port volume from the total.
Yes, winisd want the net volume. Just be sure to put in the right port measurements, to have an accurate air port velocity.

Sent from my LG-H932 using Tapatalk
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #5 · (Edited)
Well its probably ok but you didn't list the model of the sub so how could anyone check?

the volume you put into winISD is the net volume of your design. You dont put in 6.xxx and then figure out tuning and then change the volume again.. You have to consider both at the same time or iterate back and forth to arrive at the correct net volume corresponding to a gross volume available.

The port velocity plot has the wrong volume so that might be wrong.

The tuning freq seems pretty low, why did you pick that?

how much power are you running?
Thanks for the answer!
the model is Kicker 41L7154
running a 1200rms amp the input power is also the same in winisd

I picked 28hz because I want to go a little lower than 33hz and the research I did about others who did 28hz sounded nice to me.




the amp

the sub
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #6 ·
Just cut off the speaker displacement volume and port volume from the total.
Yes, winisd want the net volume. Just be sure to put in the right port measurements, to have an accurate air port velocity.

Sent from my LG-H932 using Tapatalk
Thanks for the answer! If you cut off speaker displacement and port volume won't that change the net volume completely making it bigger than it was therefore throwing off the port velocity measurement and the transfer function response because now the sub and the port is no longer there and wasn't accounted for in the design.

What am I not understanding I really want to understand.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #7 ·
software operate with net volume, so if you want to end up with let say 5cuft you will have to add to this volume all sub volumes like port, brace and speaker displacement.

Old Speakershop software was so easy and clear on that, but it only operate on very old win platforms like Win97 or 2000, lol
Thanks for the answer! Wouldn't that make the net volume larger causing a inaccurate measurement?
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #8 ·
I guess pretty much what I'm not understanding is how do you factor in the port to the final gross volume(sub, bracing). Because the gross then becomes the net for winisd to go off of??
This is a just a little confusing and a little roadblock that's all.
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #9 ·
I found this online while doing research. I'm pretty sure this answers my question about me being wrong with the calculations.

My enclosure size is all measured the displacements would add a few cubes. Once figured out the excess amount I need for the port.Whatever winisd gives me.

Also I have one question.
My box net volume is already set to for example 5³ fixed so how do I compensate for the 1³ port that would make it a 6³ box because winisd called for a 1³ port? Is there a way to adjust the net volume again to get it back to 5³ if your box is fixed to 5³ ?



Start off by messing with the measurments until you get the needed amount for your sub(s).

Ex: 34"x13"x18" = 3.56cuft internal.

How you get the cuft is take your measurments subtract 1.5 from each one and mulitply them all and then divide by 1728.

So, 34x13x18 becomes 32.5x11.5x16.5 = 6166.875, then divide by 1728 and you end up with a net volume of 3.56cuft.

Once you have your net volume you then calculate your port displacement.

Ex: Port is 18" tall x 3" wide X 30.5 long and that ends up being about 33.66hz.

What you do to calculate disp. is this...

Take the length of your port (30.5) and subtract .75 from it = 29.75"

Then multiply that by your height. (18)

Then take the width of your port (3) and add .75 = 3.75 then multiply that.

You end up with 1874.25 and once you have that, you then divide by 1728 to get your cuft.

Which is 1.08cuft.

Now once you have all of that, you then take your net volume (3.56cuft) and add your port disp. (1.08cuft) and then add your sub disp. and whatever that eqauls is how much cuft your box needs (gross volume) to end up with 3.56cuft after you add your port and the sub.
 

·
Registered
Joined
·
2,256 Posts
I guess pretty much what I'm not understanding is how do you factor in the port to the final gross volume(sub, bracing). Because the gross then becomes the net for winisd to go off of??
This is a just a little confusing and a little roadblock that's all.
The volume that software suggests as optimum or your custom entry of volume is always a net volume (add volume). All braces and port/subwoofer displacements are subtract volumes. You need to add all thoose subtract volumes to the net volume of enclosure.
If your calculation for enclosure volume is 50 liter net, your port takes up 3 litre and subwoofer driver takes 4 liter and a feb braces another 3 liter, THEN a final volume should be 50 + 3 + 4 + 3 =57 liter (all this numbers are made up just for an example)
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #12 ·
The volume that software suggests as optimum or your custom entry of volume is always a net volume (add volume). All braces and port/subwoofer displacements are subtract volumes. You need to add all thoose subtract volumes to the net volume of enclosure.
If your calculation for enclosure volume is 50 liter net, your port takes up 3 litre and subwoofer driver takes 4 liter and a feb braces another 3 liter, THEN a final volume should be 50 + 3 + 4 + 3 =57 liter (all this numbers are made up just for an example)
I understand thank you
 

·
Registered
Joined
·
1,386 Posts
Yes I tried that calculator I didn't like it because you are limited on there like not being able to edit depth of box, Thank you for the suggestion.
Well you use the other 2 dimensions + volume to change depth. Which makes a bit more sense when you design a box as you already know the net volume you're targeting and you typically have a dimensional constraint in one or two directions
 

·
Registered
Joined
·
12 Posts
Discussion Starter · #15 ·
Well you use the other 2 dimensions + volume to change depth. Which makes a bit more sense when you design a box as you already know the net volume you're targeting and you typically have a dimensional constraint in one or two directions
Hmmm.... I fiddle with it later on
 
1 - 15 of 15 Posts
Top