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View Full Version : Box i built sounds like da fudge



skylineTT
01-25-2012, 05:56 PM
Well I built a box using RE box calc as always (they usually turn out sounding alright) and to achieve the tune I wanted, it called for a 28" port length in the back.. well the box wasnt wide enough for that so I took length off of the end of the port and glued it to the wall with the port width being the distance from the port to the wall.. you can see from the pics.. anyways, I figured that the port length would still be the same but just in a diff configuration and area was the same so tuning shouldnt suffer. well it did! seems to be tuned much higher than I aimed. I also used an FI X in the box which needs about .5 cubes more than what the box offers (didn't know at the time). anybody see any design flaws in the box or is it just that the sub wants a higher freq? thanks

Calculated box. you can see the port is too long so i cut the end and placed it forward
http://i69.photobucket.com/albums/i57/all-names-were-taken/FIX.jpg


built box
http://i69.photobucket.com/albums/i57/all-names-were-taken/IMAG0426.jpg

18" of port area btw

kushy_dreams
01-25-2012, 06:05 PM
Was it a 12inch speaker that was used? If so that box is too small, needs 45s in the corners and by adding the 2nd port wall that comes in from the side, that ate into your airspace and lowered it even more.

Dont use the RE box calc, it is very inaccurate

CAT MAN
01-25-2012, 06:07 PM
because re calc is terrible

skylineTT
01-25-2012, 06:09 PM
It was a used 12 in fact.. lol it has worked well on 3 other boxes i built. what do you all use besides math? would an 8 sound better in here?

kushy_dreams
01-25-2012, 06:18 PM
I would try a 10 first, then an 8. The size is about perfect for a 10 and little on the large side for an 8. If you give exact dimensions of what you have, I can give you a final volume and tune, but it looks close to 1 cube tuned in 32-34 range.

skylineTT
01-25-2012, 06:25 PM
well the box is made out of .75, measures 24 wide, 13.5 high, and 12 deep with 1.5" port width. it is supposedly 1.2 cubes at 30hz but it doesn't play like it is. the sub displacement would subtract from that a little too, and the way i configured the port might have stolen some area from that unless the box calc factored that in.

pro-rabbit
01-25-2012, 06:28 PM
1.2 ported for a 12"? What sub are you trying to use..also that port is hell thing...not a good thing.

skylineTT
01-25-2012, 06:29 PM
haha it is an FI X i had laying around. the wood was also laying around so i didnt design it for any specific speaker. it was the biggest and lowest tuned box i could build with the little amount of wood I had. all of them were 12" by 8ft strips too.

double 07
01-25-2012, 06:36 PM
add a couple more boards and you will have a T-Line..........sorry I couldnt resist.....left off my LOL

pro-rabbit
01-25-2012, 06:38 PM
add a couple more boards and you will have a T-Line......

:eyebrow:

kushy_dreams
01-25-2012, 06:38 PM
Well I'm not the greatest at slot port calculation but heres what I came up with

24x12x13.5 overall dimensions = 2835cubic inches
subtract port displacement of 1080 cubic inches
leaves you with 1755cubic inches divide by 1728 = 1.0156 cu/ft
figure around .1cu/ft for sub displacement so about .9cu/ft

total port length is 42.25inches, combined with the port area and volume comes out to about 34.3hz tune

kushy_dreams
01-25-2012, 06:50 PM
The reason it raised it is because the added piece cut into the airspace and decreased it and the length added was not enough to maintain the same tune after the volume was decreased.

skylineTT
01-25-2012, 06:53 PM
yeah i figured, just didn't know if RE's calc considered the entire length to be internal or not. so .9 at 34-35? .. looks like 8" city

kushy_dreams
01-25-2012, 07:15 PM
Yea depending on the driver an 8 would work

VWBobby
01-25-2012, 07:24 PM
Definitely looks longer than a 40-42" port in there.....just from looking at it. The extra board decreased your net volume (took up space) so that raised the tuning a lot higher than your port calculation.

Use WinISD if you want a better calculator. I'm sure there's better ones out there, but this is what I use in a pinch. I just take the calc for a rectangle port and adapt it for use as an L-port.
LinearTeam (http://www.linearteam.dk/default.aspx?pageid=winisd)

06goat
01-25-2012, 07:33 PM
I know exactly why. You need to use more screws.

VWBobby
01-25-2012, 07:42 PM
If you are using the proper wood glue, there is NO use for screws once the glue has set. Proper glue would be Titebond 2 or 3, Elmers Professional woodglue or similar.

skylineTT
01-25-2012, 07:47 PM
yeah i know, i used the premium stuff too. it would have been fine but it just used the *screws* to tighten it for the glue to set and i didn't see a need to remove them. didnt have to use that many either but it doesn't matter really.

KyleBechtold
01-25-2012, 07:52 PM
add a couple more boards and you will have a T-Line..........sorry I couldnt resist.....left off my LOL


:eyebrow:

Ya I missed that too lol.. somewhere there is funny? idk..


OP like said before your port is to THIN.. can imagine a LOT of noise..

06goat
01-25-2012, 07:59 PM
yeah i know, i used the premium stuff too. it would have been fine but it just used the glues to tighten it for the glue to set and i didn't see a need to remove them. didnt have to use that many either but it doesn't matter really.

Lol I was just kidding.

Ill try la-mans terms here. What happened was when you added that piece to the inside it took away a lot of volume. Remember that your tuning is a variable of your port, which is a variable of the volume. Taking away that much volume changed everything. Also, where you mounted the sub could effect it even more. You typically want it as far from the port opening as possible. If you were to maybe invert the sub, depending on how big it is, it may sound better. That way the displacement of the motor wont be in the way.

ddfan24
01-25-2012, 08:37 PM
give a sa 8 a try was very impressed when i heard a pair. i also use 12volt.com for my port specs and havent been dissapointed with the outcome yet

skylineTT
01-26-2012, 10:39 AM
Lol I was just kidding.

Ill try la-mans terms here. What happened was when you added that piece to the inside it took away a lot of volume. Remember that your tuning is a variable of your port, which is a variable of the volume. Taking away that much volume changed everything. Also, where you mounted the sub could effect it even more. You typically want it as far from the port opening as possible. If you were to maybe invert the sub, depending on how big it is, it may sound better. That way the displacement of the motor wont be in the way.

lol i know brah. As stated, I just didn't know if RE's calc considered that extra port volume internal or not when describing the chamber volume to be 1.2.. I lost roughly 144in^3 by doing that if the calc didn't consider it to be internal. Even inverting the sub, I wont have near the volume necessary to make the sub sound alright.. I have a tang band 8 that I will put in there to test and see how it sounds. even without 45s in the corners of the port, it surprisingly has no port noise, even playing below tuning when the sub is just fapping (lols). I'll cover the 12" hol and try an 8 instead. we shall see how it sounds.

bubbagumper6
01-26-2012, 11:19 AM
The12Volt (http://www.the12volt.com) & WinISD (http://www.linearteam.dk/default.aspx?pageid=winisdpro) are both good for designing basic enclosures

Buck
01-26-2012, 11:59 AM
Hmm.

Ronny
01-26-2012, 12:18 PM
Hehe, oh well, live and learn right?

I do like that you took the initiative to do that though lol.

skylineTT
01-26-2012, 11:00 PM
Hehe, oh well, live and learn right?

I do like that you took the initiative to do that though lol.

Gotta do something with my boredom after work on Christmas break from school. Lol

duanebro
01-29-2012, 10:44 PM
Two TB 8"s would work also. With that much air space you are going to see a boost at tuning.

iamamp3pimp
01-29-2012, 11:35 PM
looks like you raised the tuning a little, bt decreased the volume a ton choking the sub off.



I can design you something that will preform the way you intend.......hit me up


Bass Heads ENT *Custom Speaker Enclosure Design & Fabrication - Home (http://www.bassheadsent.net)

skylineTT
02-01-2012, 04:00 PM
thanks for the offer man but I don't really need a custom design for any specific sub. I just built this out of boredom with spare wood that was laying in the back of a truck we don't drive. ;)