1. ## close to correct?

EXTERNAL
15.5tall x 13deep x 35

INTERNAL
14*11.5*33.5=5393.5
5393.5/1728=3.12
3.12-.21=2.91

port= 2.5*14=35 sq inch
port length=20.3

35 hz

im thinkin of doin 40 or even 45 sq inches of port though, what yall think

2. ## Re: close to correct?

Originally Posted by saywhat?
EXTERNAL
15.5tall x 13deep x 35

INTERNAL
14*11.5*33.5=5393.5
5393.5/1728=3.12
3.12-.21=2.91

port= 2.5*14=35 sq inch
port length=20.3

35 hz

im thinkin of doin 40 or even 45 sq inches of port though, what yall think
Port displacement is off. Remeber use 3.25 x 14 x 19.55" for the port displacement.

3.25 = the wood used for the port
19.55 = subtract .75 of the displacment for the end of the port being part of the original box measuments. Will not effect displacement.

So that would make your box size 2.38ft^3. tuned to 33hz.

3. ## Re: close to correct?

well would u be so kind to make a box a little WIDER, dont touch the height/depth to right around 2.5 or 3 (max width being 40, max depth being 15.) i gotta get this into a mustang haha. if u could do that, it would be great!

4. ## Re: close to correct?

Originally Posted by saywhat?
well would u be so kind to make a box a little WIDER, dont touch the height/depth to right around 2.5 or 3 (max width being 40, max depth being 15.) i gotta get this into a mustang haha. if u could do that, it would be great!

Actually I like the original outcome 2.38 tuned to 33hz is a decent box for say a 12.

What speaker is it???

If it requires less or more space I can do that 4 ya.

5. ## Re: close to correct?

rl-p 15.....2.5-3.5 cubes

tell me if this looks right-

INTERNAL
14*12.5*36.5=6387.5
6387.5/1728=3.69.....say 3.7
3.7*.21=3.48......say 3.5 .21=driver displacement

port=14x2.5
length=15.87 subtract .75 = 15.12
15.12*14*2.5
area=.25

3.5-.25=3.25

6. ## Re: close to correct?

Originally Posted by saywhat?
rl-p 15.....2.5-3.5 cubes

tell me if this looks right-

INTERNAL
14*12.5*36.5=6387.5
6387.5/1728=3.69.....say 3.7
3.7*.21=3.48......say 3.5 .21=driver displacement

port=14x2.5
length=15.87 subtract .75 = 15.12
15.12*14*2.5
area=.25

3.5-.25=3.25
Nope, remember this being a slot port one of the walls you will be using a piece of wood to make it. so this would increase your port displacement. So your 2.5 becomes 3.25"

Keep that box make the port 14 x 2.5 x 19. That will tune you to 35hz

7. ## Re: close to correct?

problem is...i need to make a step up in the floor of the box so im gunna have to most likely have 2 turns in the port, what do u subtract from the length at each turn? im about to draw what u said into sketch up to see it visually, can u explain how u got 19 for the length?

8. ## Re: close to correct?

more than one bend = same thing, just add the .75" to the port side wall measurment when factoring in displacment.

Your box 15.5 x 14 x 38 = 3.70ft^3
Speaker disp. = .21
Total box size before port displacement - About 3.5ft^3

With a port of 14 x 2.5 x 19 = .5ft^3

So total box size would be 3.0ft^3.

To tune the box to 35hz it would take a length of 20.78" factor in the side wall(remember slot port) it comes out to 19.53". I removed the .5" from the length to compinsate for the .75" of the box not factored in to displacement on the port.

So to keep it simple I gave you 19" which would tune you to 35.25hz.

If you want to be 100% accurate and get 35hz not 35.25hz then make the port 19.36"

EDIT - Bold = port end correction. That is what it is called.

9. ## Re: close to correct?

I'm being way to productive today

10. ## Re: close to correct?

so if i do take a couple bends dont worry bout subtracting anything, just make it the 19 inches.

11. ## Re: close to correct?

...i was lookin shady on that jmac.....care to explain?

12. ## Re: close to correct?

Originally Posted by Jmac
In the first one, it's 2.416 ft^3 tuned to 41.4 Hz ... He got port displacement wrong (assuming it's an L-shaped port) and used gross volume for calculating the tuning frequency instead of net volume ...

In the second one, I get 2.993 ft^3 tuned to 36.86 Hz using a straight port (would have to fire sideways and it would be 20.75" - 2.5/2 - 0.75 = 18.75" not 19" anyways) and 3.013 ft^3 tuned to 36.74 Hz using an L-shaped port ...
Maybe I did not calculate the port displacement for an L shaped slot port. Jmac do you care to explain where i went wrong on it???

13. ## Re: close to correct?

I just went over it again. And this is what I got.

Construction Material = 3/4" MDF
Box Height = 15.5"
Box Width = 38"
Box Depth = 14"
Number of Ports = 1 (Slot)
Diameter of Ports = 14" x 2.5"
Length of Ports = 19.9"
Port Area = 35 square inches
Box Volume = 2.97 ft^3
Box Tuning = 34.87Hz

All of this was done by hand. So could someone please verify the numbers. If you find a mistake please point it out with the correction. I'm pretty sure this to be accurate to my knowledge.

This kept me up So I had to try and find what happened. Thanks Jmac.

14. ## Re: close to correct?

jmac, ill be getting plans from u this weekend.

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