10 cu.ft. @ 33hz (2 HDC3 18's)

[SSS 18734 5,000+ posts]

This design is for team3d and his pair of 18" HDC3's. I'm trying to get better at designing boxes in Google Sketchup, so critiques/comments are welcome.

To be exact, it is 9.92 cubic feet tuned to 33.3 hz after all displacements. There are 85 square inches of port.

Step 1 - I left enough clearance for you to use flared aeroports. I'm not sure how to draw them in sketchup. Those guide lines will get you the center of the port.

Step 2 - if you choose to brace differently, the brace displacement is .25 cu.ft.

Step 3

Click to read more...

 

[Pioneer~Saturn 5,000+ posts]

I would like to see more port area...but doesnt look bad

 

[SSS 18734 5,000+ posts]

I would have added more area using a slot port, but he wanted aeroports. 6" is an easy size to come by, and adding extra ports would have made them way too long. I think if he uses flared ports, he should be okay in terms of noise.

 

[WhiteIce 10+ year member]

tune higher

 

[Rashaddd 5,000+ posts]

Why @ 33? Coulda used more port and tuned higher

 

[tez4life Premium Member]

tune higher

x2, 35hz at a min. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Plenty of HDC3 18 owners tune at 38hz, and still own the lows //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[team3d 10+ year member]

ok the reason for 33hz is cause its what i suggested. I could deal with 35hz but no higher. if someone could tell me how to make it 35 so he doesnt have to redo this i would be thankful.

Also thanks sss for doing this for me

 

[SSS 18734 5,000+ posts]

If you wanted to make the tuning 35hz, just make the ports 14" long instead of 16".

You could also make the box an inch less deep, and make the ports 15" long, for a ~35hz tune.

According to WinISD, a 33hz tune will roll off at 29hz, whereas a 35hz tune will roll off at 30.5. The 35hz tune has a peak output of about +1db over the 33hz tune. The curve will look much different in the vehicle, of course, but you should still get wicked output all the way down to the mid twenties with either one. There shouldn't be much of an audible difference between the two.

 

[team3d 10+ year member]

How do you feel about the port area?

 

[RAM_Designs 5,000+ posts]

How do you feel about the port area?

I always use slot ports to get 2x the port area I can with aeros...

 

[team3d 10+ year member]

Here is a question for anyone that can help.The flared aeros im getting are weird. The back flare and front flare are the same diameter. If i shave some off the diameter of the back flare so i can remove the ports when needed will it hurt me sound wise?

 

[PSturmer 10+ year member]

According to WinISD, a 33hz tune will roll off at 29hz, whereas a 35hz tune will roll off at 30.5. The 35hz tune has a peak output of about +1db over the 33hz tune. The curve will look much different in the vehicle, of course, but you should still get wicked output all the way down to the mid twenties with either one. There shouldn't be much of an audible difference between the two.

once you actually build boxes to winisd specs you'll quickly find out it is not very accurate. it is useful for many things, but in this case it is not. plenty of people have used these subs and have real world experience with them, so your much better betting your money with them.

 

[team3d 10+ year member]

I am doing 35hz no higher

 

[SSS 18734 5,000+ posts]

I actually have a question as well; when using flared ports, do the flares themselves affect the tuning?

For example, if the pipe between the flares is 16 inches, would he actually get a lower tuning when he added the flares? Or would it stay the same?

 

[SSS 18734 5,000+ posts]

once you actually build boxes to winisd specs you'll quickly find out it is not very accurate. it is useful for many things, but in this case it is not. plenty of people have used these subs and have real world experience with them, so your much better betting your money with them.

I realize that; I even said it in the post. The point of it was to show him how theoretically, 33hz and 35hz tunings should yield largely similar results, which they will.

The difference between 33 and 38hz will be more substantial, but he will still gain low-end extension with a 33h/35 hz tuning.