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View Full Version : A little mis-calculating, need yalls opinions ASAP.



Spud2388
06-25-2006, 04:38 PM
Ok, I finally have finished putting my box together, and its volume is 5.898 cuft after sub displacement. I put that figure into the forluma and to reach my goal of 32 hz, I got 2 6" round ports at 20.88" long. After port displacement, the final volume is 5.218 cuft. Is that too much for 2 12" Type R's ('06 versions)? It's not a SPL box my any means, I'm just afraid its going to be real boomy and not sound as good as a 4 cuft box would, which is what I was aiming at but somehow my calculations got messed up :blush: . What's yalls opinions? Should I add some wood in the inside to decrease the volume or leave it alone? They're going to be powered off of a nine.1 if ED ever gets some in. I still have to put braces in it, so that should knock the volume down a little, but not 1 cuft.:crap:

jd_man_90
06-25-2006, 04:51 PM
just wondering, why don't you just redo your calculations to make a smaller box?

jd_man_90
06-25-2006, 04:51 PM
My bad just re read it and realized you allready built it

springy101
06-25-2006, 04:55 PM
no its fine 2 12"s

xluben
06-25-2006, 05:16 PM
Correct me if I'm wrong, but I think you need to use the box volume with port displacement removed when calculating tuning frequency.

With 2, 6" ports, 20.88" long and a 5.218 cu.ft. box Win ISD is telling me 34Hz tuning frequency.

Fast1one
06-25-2006, 05:20 PM
Correct me if I'm wrong, but I think you need to use the box volume with port displacement removed when calculating tuning frequency.

With 2, 6" ports, 20.88" long and a 5.218 cu.ft. box Win ISD is telling me 34Hz tuning frequency.He already factored in ports....re-read the thread....

SHould be fine for two type Rs. Put them in and see how they sound :)

xluben
06-25-2006, 05:37 PM
He already factored in ports....re-read the thread....

SHould be fine for two type Rs. Put them in and see how they sound :)

My understanding is he took the net internal volume and used that to calculate the port length, and then subtracted the port volume. That also corresponds to my quick type-in's with WinISD. But I could be wrong or have misunderstood, either way it doesn't really answer his question.

Spud2388
06-25-2006, 06:02 PM
Correct me if I'm wrong, but I think you need to use the box volume with port displacement removed when calculating tuning frequency.

With 2, 6" ports, 20.88" long and a 5.218 cu.ft. box Win ISD is telling me 34Hz tuning frequency.

I thought about that too, but got to thinking and couldn't figure out how. You'd be trying to find the port length using the volume of the port, which the port length is needed to find, so you'd get nowhere. Kinda confused. I think I found everything right, didn't I?

xluben
06-25-2006, 06:09 PM
I think your problem was building a box without first calculating the port lengths!

If you did it the other way around you could just use WinISD to do it.

If you have the actual equations for calculating tuning frequency I would think that through some kind of substitution you could solve for the variable in question.

Spud2388
06-25-2006, 07:43 PM
I think your problem was building a box without first calculating the port lengths!

If you did it the other way around you could just use WinISD to do it.

If you have the actual equations for calculating tuning frequency I would think that through some kind of substitution you could solve for the variable in question.

I agree, but you learn form your mistakes:crying: . So, with a box that is 5.898 cu ft after sub displacement, and I plan on using 2 6" round ports, what length would I need to make them to get the 32hz I'm looking for? 20.88" as I said before? What would be the final volume and tuning the subs would see after port and sub displacement?

xluben
06-26-2006, 12:13 AM
With the ports you're thinking of it should be tuned to ~34Hz according to WinISD.

Spud2388
06-26-2006, 09:49 PM
so what length ports do I need to make to make it 32 hz?

2 6" round fyi

Spud2388
06-27-2006, 05:12 PM
Ok, I guess I need to go back to the origional question. Do yall think I should lower the volume to around 5 cu ft after sub displacemnet and make my port off of that, which in turn should give me a final volume of around 4 cu ft? The reason I ask is because I have mostly read people recomending 2 cu ft per sub tuned to around 28-33 hz, so with 2 subs, 4 cu ft would be ideal. I really dont want boomy bass, i want something what will appeal to all styles of music.



And in a way, I'm kind of glad I made the box bigger than what I wanted, cause you can always make a box's volume smaller by adding things on the inside, but its a little harder to make a box bigger, without starting over.

Spud2388
06-28-2006, 07:24 AM
bump, bump, bump

Spud2388
06-28-2006, 07:25 PM
ur killing me guys!!!:crying: :D i'm ready for BASS!!!!!

Spud2388
06-30-2006, 12:20 AM
Here are some pics that might encourage yall to help me a little. (I'm begging) And sorry for the large pics, Imageshack crapped out on me, so I had to try something different.

Front/Top
http://img440.imageshack.us/img440/2158/img04182ce.jpg (http://imageshack.us)

Front
http://img222.imageshack.us/img222/1830/img04192xr.jpg (http://imageshack.us)

Side
http://i83.photobucket.com/albums/j281/spud2388/IMG_0420.jpg

Front'Inside
http://i83.photobucket.com/albums/j281/spud2388/IMG_0424.jpg

Back/Side
http://i83.photobucket.com/albums/j281/spud2388/IMG_0423.jpg

Back
http://i83.photobucket.com/albums/j281/spud2388/IMG_0422.jpg

Back Side
http://i83.photobucket.com/albums/j281/spud2388/IMG_0421.jpg

My Port!
http://i83.photobucket.com/albums/j281/spud2388/IMG_0425.jpg

My Canvase
http://i83.photobucket.com/albums/j281/spud2388/IMG_0426.jpg

How the ports will run
http://i83.photobucket.com/albums/j281/spud2388/IMG_0429.jpg

I'm going to do one more measurment to get the exact interval volume, but I'm pretty sure its around 6 cu ft. When I get the exact volume, will somebody tell me what length ports I need to reach my desired volume?? Thats all I need, and I don't want to screw up because 6" PVC is a little pricy.

xluben
06-30-2006, 12:30 AM
looks aweseome!

i'll try and do the calculation sometime this weekend.

Spud2388
06-30-2006, 12:35 AM
Let me explain my box a little bit. The sides are extended outward so they go over the wheel wells. The top is made in a stairstep to allow me to use my cargo cover. The subs are going to be in the middle (big holes) and the ports are on the bottom left and right corners and will go in, then curve and go around the back and end up facing each other. The back slants to the shape of my rear seats and bracing is still needed. I'm thinking one brace form the front to the rear (between the subs), and two more from the bottom to top (behind each sub). I had to include those two triangle pieces on the front because with the way my amps will be mounted, I would have two visible holes. Plus it makes the box look bigger.

If that makes any since to yall, good. I still need to cut the holes for the terminals (which I don't have), cut the ports to the proper length and install them, make amp racks (waiting on nine.1 that was shipped today), carpet/vinyl everything, and finally install it all. I have a crap load of work ahead of me, but it should be fun.

BTW- I got a little silicone happy, so this thing isnt going to leak, period.

Tell me what you think. All feedback is wanted and appreciated.

Spud2388
06-30-2006, 12:38 AM
looks aweseome!

i'll try and do the calculation sometime this weekend.

Oh, you have time. I'm leaving to go to the beach sat and want be back until wed, so I'll get the final specs out to yall tomorrow. I'm thinking anywhere from 30 hzz to 32 hz.

Spud2388
07-07-2006, 08:07 PM
Ok, sorry for being so long on the final specs. There's been a lot going on with vacation, work, family, ya-da-ya-da. So, as of now, with the subs and bracing included, I'm looking at 5.5 cuft. Will someone PLEASE give me the port lengths I need to use to reach 31 hz (couldn't decide between 30 hz or 32 hz). I will be using 2 6" round ports, PVC. I would also like to know what the final volume is with port displacement. Sorry for being picky, but I've looked at my equipment for over 3 months sitting in my room and just want it installed.

Thanks in advance!

Spud2388
07-08-2006, 02:31 PM
daily bump :thankyou:

Spud2388
07-09-2006, 06:22 PM
BUMP ^^^^^^^^^^^^^^^^^^^^:crying: :blush: