PDA

View Full Version : 10 cu.ft. @ 33hz (2 HDC3 18's)



SSS 18734
02-22-2009, 07:28 PM
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.
http://img24.imageshack.us/img24/2879/step1s.jpg

Step 2 - if you choose to brace differently, the brace displacement is .25 cu.ft.
http://img155.imageshack.us/img155/1521/step2.jpg

Step 3
http://img3.imageshack.us/img3/4087/step3y.jpg

Pioneer~Saturn
02-22-2009, 07:31 PM
I would like to see more port area...but doesnt look bad

SSS 18734
02-22-2009, 07:34 PM
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
02-22-2009, 07:36 PM
tune higher

Rashaddd
02-22-2009, 07:41 PM
Why @ 33? Coulda used more port and tuned higher

tez4life
02-22-2009, 07:41 PM
tune higher

x2, 35hz at a min. :)

Plenty of HDC3 18 owners tune at 38hz, and still own the lows :fyi:

team3d
02-22-2009, 07:47 PM
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
02-22-2009, 08:03 PM
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
02-22-2009, 08:14 PM
How do you feel about the port area?

RAM_Designs
02-22-2009, 08:19 PM
How do you feel about the port area?

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

team3d
02-22-2009, 08:23 PM
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
02-22-2009, 09:37 PM
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
02-22-2009, 09:44 PM
I am doing 35hz no higher

SSS 18734
02-22-2009, 10:09 PM
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
02-22-2009, 10:15 PM
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.

SSS 18734
02-23-2009, 03:36 AM
Here is a slot port if you decide to go that route. 132 sq.in. of port. You could make it bigger, but then you would have to bend it inside the box, which isn't worth doing for an extra 10-20 sq. in. of port.

Specs are approximately 9.5 cubic feet tuned to 35hz. Feel free to cut holes in the brace as necessary. Also, I didn't change the external dimensions, so the double baffle will be exactly the same.

http://img510.imageshack.us/img510/9685/slotport1pic.jpg

http://img8.imageshack.us/img8/2845/slotport2pic.jpg

mlstrass
02-23-2009, 11:17 AM
I am doing 35hz no higher

Have you heard a lot of HDC's tuned to 38Hz and thought the lows were missing? I've done a bunch of HDC boxes all tuned to 38Hz and they kill on the lows and have good output.

I've also done them at 35Hz and you'll get exaggerated lows and lose some output, which may be what you want :crazy:

groundpound4200
02-23-2009, 11:20 AM
I have one HDC315 in 3.5 cubes tuned to 32HZ right now and I dont like it very much. Very peaky and only plays the lows. Its what I had laying around and its too cold in MN to finish up my other box.

team3d
02-23-2009, 07:08 PM
[QUOTE][

Have you heard a lot of HDC's tuned to 38Hz and thought the lows were missing? I've done a bunch of HDC boxes all tuned to 38Hz and they kill on the lows and have good output.

I've also done them at 35Hz and you'll get exaggerated lows and lose some output, which may be what you want /QUOTE]
So how low will they drop at 38hz? How much shorter do I need to make the port in the drawing to get 38 hz?

SSS 18734
02-23-2009, 07:30 PM
Make it 15" long for a 38hz tune.

A better idea is to increase the port to 28 inches wide and make it 20 inches long to get 168 sq.in. of port.

team3d
02-23-2009, 07:33 PM
Did you mean to say that like that. Cause the 28 inches longx6 inches high equals 168 sq. inches of port. If I do it that way are you saying make it 20 inches long? for what htz?

SSS 18734
02-23-2009, 07:45 PM
Never Mind

team3d
02-23-2009, 07:47 PM
How did that look on the isd?

SSS 18734
02-23-2009, 07:48 PM
It still looks good on WinISD. A little loss on the lows, but it doesn't roll off until 30hz. Keep in mind the actual curve will look nothing like this when its actually in your car.

ha, that port is actually taking up quite a bit more space than I thought it would. Let me re-do the box real quick so its in between 8 and 9 cubic feet.

team3d
02-23-2009, 07:59 PM
Well the reason I asked is cause I want the lows but not to worried about the ones below 30htz. Just in the general area so ill go with it at 38. I just ordered the subs so I will get a build log started like thursday or friday

SSS 18734
02-23-2009, 08:24 PM
8.93 cubic feet @ 38.15hz with 156 sq.in. of port

External box dimensions are unchanged from the first box, so use those in conjunction with this one to get all of your cuts.

http://img18.imageshack.us/img18/1293/96733034.jpg

http://img11.imageshack.us/img11/1923/40212585.jpg

The predicted WinISD curve, 30hz is still only -5db, but will be much flatter in-car.

http://img144.imageshack.us/img144/5250/winisd.jpg

team3d
02-23-2009, 11:21 PM
What do you mean by that?