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View Full Version : tuning a box lower after it was already built?



jsluss17
10-31-2011, 01:02 AM
i built my box for my sa-12 tuning it at 32 hertz and i wish i could tune it lower than that. is there any way i could tune it lower without removing anything? like if i could just add on to it or something because i'd like to get the lows better

Ninesvnsicks
10-31-2011, 01:04 AM
Longer ports = lower tuning.

Moble Enclosurs
10-31-2011, 04:07 AM
The problem with that is, changing the physical parameters of the enclosure after it was designed originally, will change the way the driver performs, not so much as just how the box performs. Because our hearing can adjust quickly to these changes, many people do not notice a difference after a few days, but parameters such as excursion and power handling may change, which will create a different load for your amplifier as well. I'm just saying, altering a box after it is already built for a specific driver, can make it possibly undesirable and can change the way the driver performs all together. And its possible you may want to end up doing a new one after a while. I would recommend another design from scratch, because tuning is not a controlling factor in most designs built for music. ..since that is the sole purpose of your request. We need to not rely so much on tuning frequencies as we do cutoff points and passband response as a whole.

Bettr n' Revrse
10-31-2011, 04:11 AM
How much lower do you want? Sounds like someone should have bought a Skar not and SA lol

fasfocus00
10-31-2011, 11:33 AM
you could also line the walls with polyfill batting, wont work wonders but will do what you want.

Danometal
10-31-2011, 12:01 PM
If your box has a slot port, you can add another section to the inner port by going through the sub cutout, and attaching with L brackets, and then using silicon or whatever. You will have to calculate the total loss of net volume to get your new tuning though. Another method is to add a piece of mdf to the port wall(s) to reduce the port area, which will lower the tuning. Also, adding polyfill will lower tuning by a couple hz. I've used all 3 methods in the same box with great results. My frankenstein box is still going strong in my Nephew's Cherokee. It hits way lower than it did originally.

Vossy
10-31-2011, 12:02 PM
Last resort you could cover some of the port

hispls
10-31-2011, 12:06 PM
If your box has a slot port, you can add another section to the inner port by going through the sub cutout, and attaching with L brackets, and then using silicon or whatever. You will have to calculate the total loss of net volume to get your new tuning though. Another method is to add a piece of mdf to the port wall(s) to reduce the port area, which will lower the tuning. Also, adding polyfill will lower tuning by a couple hz. I've used all 3 methods in the same box with great results. My frankenstein box is still going strong in my Nephew's Cherokee. It hits way lower than it did originally.

This^^^


Really I can't see tuning a box for a 12 like that any lower than you are. If you really need sub 30hz you should have either gone for more cone area, or a LMS or XBL^2 or other exotic technology driver.

Have you tried even just moving the box around, aiming different directions, firing sub at walls? Often just the position and aiming of the box wil make more difference in overall response than just tuning up or down a few cycles.

Danometal
10-31-2011, 12:26 PM
Oh yea, keep in mind that, if you can't afford losing any net volume, reducing the port area will not affect your volume, but adding inner port length will. A 4th method to consider is to build an external port to attach to the existing port opening. You can wrap it around the box or something, but it will be epic ugliness for the eyes.

Bass Addict
10-31-2011, 12:55 PM
not to deviate from this guys thread but i have a question on my box that does pertain to this thread and if someone could help me figure my tuning and cubic^3,i would appreciate it.love my box.i would really like to know the "EXACT" tuning though.
box is;
30" wide with a double face 3/4" mdf
16" deep
13 1/2" tall
slot port is 2 1/2" wide
12" tall
around 14" in total length
here is the kicker,i had this box originally in my house with a plate amp bolted to it.i took the plate amp out and put a 10x10" 3/4" piece of MDF mounted on the inside of the box to cover the whole.anyone want to help me figure it out ? yea,its a frankenstein box as well.when i get my havoc,i want to build a box to this tuning as i love it

Phoenix Risen
10-31-2011, 01:36 PM
got bass....

make your own thread.

pro-rabbit
10-31-2011, 01:42 PM
not to deviate from this guys thread but i have a question on my box that does pertain to this thread and if someone could help me figure my tuning and cubic^3,i would appreciate it.love my box.i would really like to know the "EXACT" tuning though.
box is;
30" wide with a double face 3/4" mdf
16" deep
13 1/2" tall
slot port is 2 1/2" wide
12" tall
around 14" in total length
here is the kicker,i had this box originally in my house with a plate amp bolted to it.i took the plate amp out and put a 10x10" 3/4" piece of MDF mounted on the inside of the box to cover the whole.anyone want to help me figure it out ? yea,its a frankenstein box as well.when i get my havoc,i want to build a box to this tuning as i love it

Just a quick estimate would be 2.3ft3 after displacements and 43hz or so for tuning. I could be wrong as I just did that off the top of my head while waiting in traffic.






For the OP-
What are the specs on your enclosure? This would help more then just guessing at everything. I agree with mobile though. Better off to start again if you don't like the output of this enclosure.

TheUnderFighter
10-31-2011, 02:05 PM
I'm not sure how well it works, but I know Poly-fill is supposed to trick the driver into thinking it's in a larger enclosure, which could help your driver hit the lows better. Also, SKARs are known to hit the lows quite a bit better than the SA's, just for future reference.

Bass Addict
10-31-2011, 02:42 PM
Just a quick estimate would be 2.3ft3 after displacements and 43hz or so for tuning. I could be wrong as I just did that off the top of my head while waiting in traffic.really ? 43 ? wow i thought it was lower than that ! im really surprised that this d6 is hittin the lows extremely well then

pro-rabbit
10-31-2011, 06:45 PM
really ? 43 ? wow i thought it was lower than that ! im really surprised that this d6 is hittin the lows extremely well then

Is your length right? I have not double checked my math yet, but it should be close to accurate at least.

jsluss17
10-31-2011, 08:56 PM
yeah i tried the polyfill and it didnt really do anything it might've changed the tuning a little bit but it seems quieter and doesn't hit as hard. I was just wondering if there was any easy way i could it's not needed really i don't need it though. thanks for all the help

wenn_du_weinst
10-31-2011, 09:03 PM
change teh way your box is facing until you change the q factor lower

5dollaFtDong
10-31-2011, 09:14 PM
Maybe you can add additional baffles where the slot opening is. Depending on how much lower you want to tune, you could cut square rings the size of the port, stack them, 2 or 3 high, and use say a 1" roundover bit on the sides to make it look less ghetto.

pro-rabbit
10-31-2011, 09:19 PM
I would still like to know more about the enclosure itself. Height, width, depth, port area, port length. Any pictures would also help. These things are needed before you can really take any of these ideas into consideration to try.

wenn_du_weinst
10-31-2011, 09:21 PM
wait a second you didn't follow that bullshit rule of setting your subsonic 5hz under tuning did you?

Moble Enclosurs
10-31-2011, 10:02 PM
here is the thing....if you are not utilizing a port that is long enough to cause self compression related to the frequencies of interest, or matching them anyhow, then the compression area will have most of the control over the tuning of the design. So, if you are to try this, the best way is to increase the compression area for lower tuning, that will have more of an effect than making the port longer, which might actually lower output, not just frequency tuning. So, as I said before, jsut doing another design is recommended unless you can utilize the most efficient way to lower tuning in any design that uses a smaller than optimal port volume, which would be to increase compression area. But again, there is always a trade off. So, without knowing the trade off, just design a new one. That is your best bet. Not saying it cannot be done, but doing it the most efficient way in your case might be implausible.

jsluss17
10-31-2011, 10:40 PM
the box is 22 wide by 19 deep and 11 high. it's supposed to be tuned to 33 hertz i think but i'm not really sure. the batting inside of it just made it a lot worse lol probably not my best idea so im just gonna take it out. will making the actual port thinner do anything? like adding a piece of wood to the side of it on the port to the left side so where the air is coming out?

pro-rabbit
10-31-2011, 10:44 PM
What are the port dims? That enclosure is very small, what do you have in it?

jsluss17
10-31-2011, 10:49 PM
the long one is 15 3/4 and the L part is 4 inches long. i have an sa-12 in there and it's like the biggest enclosure i could fit in my car (2003 mustang)

pro-rabbit
10-31-2011, 10:54 PM
So what your saying is the outside dims of the enclosure are

22 wide
19 deep
11 high

The port is 20(ish) long

How wide is the port? This box is very very small and should house an 8 or maybe a 10"

dbeez
10-31-2011, 10:58 PM
Bigger box can fit in there its been done.

jsluss17
10-31-2011, 11:06 PM
the ports 1.75 inches wide. well it's the biggest box i could easily fit in there unless theres better dimensions? it's about 1.75 cubic feet before displacement so it's almost as big as sundown calls for

pro-rabbit
10-31-2011, 11:10 PM
1.97ft3 gross

the port is small, what is the height of the port?

jsluss17
10-31-2011, 11:41 PM
i think it's probably 9 and a half inches high i would guess

pro-rabbit
10-31-2011, 11:55 PM
Well from what I can tell your port area is small, your enclosure size itself is not to bad at 1.5(ish) after displacements. Perhaps swapping to a precision port would be the best bet for your application.

jsluss17
11-01-2011, 12:25 AM
what do you mean precision port? and how would i do that? sorry i'm new to building boxes

pro-rabbit
11-01-2011, 12:32 AM
Let me see if you have to room to do so.

By precision port I mean a plastic round flared port.

jsluss17
11-01-2011, 02:21 AM
so like an aeroport then?

Odd-io
11-06-2011, 03:21 PM
the long one is 15 3/4 and the L part is 4 inches long. i have an sa-12 in there and it's like the biggest enclosure i could fit in my car (2003 mustang)

yourenotdoingitright


Bigger box can fit in there its been done.

One of my old setups was 5 cubes@28hz. Current is 4.2 sealed.

http://i45.photobucket.com/albums/f69/diligentdave/trunkage/DSCF0689.jpg