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View Full Version : 1243d with bandpass help!



iggiafrica
03-29-2012, 04:15 PM
Hello! Im new to the forum...kinda. ive been living off of everyone heres help for a while now, and decided it was probably time to make an account instead of just sniping the forums haha.

Anyways, before everyone starts flaming me saying "just do sealed/ported, bp ***** etc" i know the differences, i know what i want and i want a 4th order...i had one for a single 12 oldschool fosgate that put out 300 watts and sounded like 600 with an excellent frequency range!

So now ive bought 2 alpine 12s, 2 mrp m500 amps and have unlimited mdf to work with, i just cant seem to get my measurements to produce what i want.

Id made a box last week but the ports were 4.25" wide x 22" long and it had little efficiency below 50hz, but destroyed everything above that!

Id just like help building one that will have a nice rumble around 31hz with good range. Ive tried winISD and i guess im too illiterate to understand it fully... Ive got 15"h x 32" w x 29" L to work with...i know its doable, im just having a hard time understanding port widths and stuff... I guess it has the same effect if it was short and wide as if it were thin and long? Im not really understanding it... If someone could explain it to me i would be so greatful!!

Thanks in advance!
-iggi

DoesDad
03-29-2012, 04:32 PM
Can't help. Don't like bandpass.:imo:

iggiafrica
03-29-2012, 04:40 PM
Ive seen alot of people say that lol!

Well could you explain port sizes and difference to me for just an average ported box?

DoesDad
03-29-2012, 04:47 PM
The box builders on here are usually pretty helpful. You know you can get a design for really cheap. Maybe 15-25 bucks (don't quote me on that). That would be the way to go for you cause it sounds like you've got some construction skills. Pro-rabbit, mobile enclosures, Donh, buck, etc....

iggiafrica
03-29-2012, 05:00 PM
I may end up doing that, but id still like to know what makes things do what they do...i always love learning the reasons behind how things work haha. If i did have someone design it for me theyd probably have to explain why the port would have to be the size it is and what that would cause (lengths in soundwaves and so on) im just that kinda guy haha

DoesDad
03-29-2012, 05:05 PM
There's actually a couple acoustic guys on here (can't remember names). Actually think one or two might be schooled in it. They'll probably chime in too. I can't help you my man. I just order boxes. Lol! Tell the guy how much room I have, what I want it to do and place my order. Bada bing.

wenn_du_weinst
03-29-2012, 05:10 PM
I'm confused on why your stuck on bandpass?

CAT MAN
03-29-2012, 05:24 PM
bandpass isnt that bad. you just need to know what you're doing

iggiafrica
03-29-2012, 06:43 PM
Exactly! Im just stuck on bandpass cuz i know the potential of it... I want to be able to understand it. I slapped a sealed box in my rig for the time being but i miss the rumble... Sq is great but im an spl guy and 4th orders intregue me..i want to know it all haha

iggiafrica
03-30-2012, 12:01 AM
So i drew up a design for a box.. sealed (if i remember right) is 1.23^ft3 per sub, the ported section before the ports is 3.29^ft3, and the ports (2) are 30.75 long, 13.5 tall and 2" wide...what kind of tuning am i looking at? And how do i figure it out from these parameters? (I prefer doing the math by hand rather than using programs lol) so...what do i have?

KyleBechtold
03-30-2012, 12:10 AM
its all realitive.. the sealed to the ported section is realitive along with the tuning.. I just built one for two t3s I did 2cubes ported 2.5 sealed 18" long port 40" of port..

TaylorFade
03-30-2012, 12:12 AM
If you have unlimited MDF to play with, just start building until you get it right. Lol.

30.75" long? What are you tuning to? 30hz? BP's don't work like regular ported. MOST tunes are ~ 50hz. Not all, but most.

If you don't want to pay someone, I'd start here... 1cf each sealed, 2cf each ported tuned to 50hz. This is a pretty standard ratio. Bigger ratio will get you a bigger peak around tuning. Smaller ratio will flatten the response out. Generally speaking.

Here's a port calculator for you. I don't know anyone that can do the tuning by hand.
Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators (http://www.the12volt.com/caraudio/boxcalcs.asp#porsq)

CAT MAN
03-30-2012, 12:14 AM
If you have unlimited MDF to play with, just start building until you get it right. Lol.

30.75" long? What are you tuning to? 30hz? BP's don't work like regular ported. MOST tunes are ~ 50hz. Not all, but most.

If you don't want to pay someone, I'd start here... 1cf each sealed, 2cf each ported tuned to 50hz. This is a pretty standard ratio. Bigger ratio will get you a bigger peak around tuning. Smaller ratio will flatten the response out. Generally speaking.

Here's a port calculator for you. I don't know anyone that can do the tuning by hand.
Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators (http://www.the12volt.com/caraudio/boxcalcs.asp#porsq)

or 1.3 and 3 at 46.....because big 4ths are loud 4ths

TaylorFade
03-30-2012, 12:17 AM
or 1.3 and 3 at 46.....because big 4ths are loud 4ths

Big 4ths are peaky 4ths. He's only got like 8 cubes anyway.

CAT MAN
03-30-2012, 12:18 AM
Big 4ths are peaky 4ths. He's only got like 8 cubes anyway.

hence why they get loud :p.... only 8 cubes he could do 1-1:5 ratio if he wants a more controlled response.

iggiafrica
03-30-2012, 12:26 AM
so smaller ratio provides flatter response? And more area is louder? As a rule of thumb...not always ofc lol

CAT MAN
03-30-2012, 12:26 AM
so smaller ratio provides flatter response? And more area is louder? As a rule of thumb...not always ofc lol

smaller ratio is flatter larger ratios are peakier but louder. usually for spl

TaylorFade
03-30-2012, 12:35 AM
If you play with the chamber volumes in winISD, you can see how they affect the frequency response. Don't take that BS as gospel, but it'll give you an idea of what we're talking about.

CAT MAN
03-30-2012, 12:36 AM
Don't take that BS as gospel,

taylorwin!

iggiafrica
03-30-2012, 12:45 AM
For whatever reason i cant seem to get winisd to do what i want...i dl'd pro before work so ill check it out when im home but im not fully understanding it i guess..

TaylorFade
03-30-2012, 12:47 AM
Just run the little applet. That's all you really need to fool around with it.

CAT MAN
03-30-2012, 12:48 AM
Just run the little applet. That's all you reall need to fool around with it.
or if he has xp BBP6 would work .....more complicated tho ._.

MisterDeadeye
03-30-2012, 12:50 AM
Bass Box 6 FTW.

TaylorFade
03-30-2012, 12:51 AM
Bass Box 6 FTW.

Unlimited MDF, sawdust on the floor and TL FTW. Screw those **** sims.

MisterDeadeye
03-30-2012, 12:53 AM
Unlimited MDF, sawdust on the floor and TL FTW. Screw those **** sims.

Don't make me feel bad now. :crap:

CAT MAN
03-30-2012, 01:04 AM
Unlimited MDF, sawdust on the floor and TL FTW. Screw those **** sims.
well with most people they dont have that. honestly i cant remember the last time i used one of those. now i had some pwk software from a while back that he actually did himself i guess that was on my old computer tho

Don't make me feel bad now. :crap:

:uhoh: only in bed :naughty:

iggiafrica
03-30-2012, 01:07 AM
So what effect would a shorter but wider port have? The same basically? Or completely different?

CAT MAN
03-30-2012, 01:09 AM
So what effect would a shorter but wider port have? The same basically? Or completely different?

smaller port area=more controlled

TaylorFade
03-30-2012, 01:14 AM
So what effect would a shorter but wider port have? The same basically? Or completely different?

With a much higher tune from what you were trying to do, you'll be able to do more area and shorter length too. If you're talking about a width to height ratio, try to keep it under 9:1. i.e. don't make it 20" wide and 1" tall.

iggiafrica
03-30-2012, 03:19 AM
I can't get the subs specs into winisd... ive put in everything i can and it gives me this....

http://i44.tinypic.com/mm55ax.jpg

I don't know what to fill in for the things that are missing.... lol. This is why i keep saying "I can't get it to work"...

iggiafrica
03-30-2012, 01:26 PM
Also, whats the result of too little port area? Facing subs toward eachother head on? Facing them together at 45 degrees? Having the type rs playing 5-10 h wont damage them, will they? The specs say range is 20-200...any leway?

I really appreciate all your help... A month ago i didnt know the first thing about car audio...but this forums been amaing! You guys rock haha

CAT MAN
03-30-2012, 01:29 PM
Also, whats the result of too little port area? Facing subs toward eachother head on? Facing them together at 45 degrees? Having the type rs playing 5-10 h wont damage them, will they? The specs say range is 20-200...any leway?

I really appreciate all your help... A month ago i didnt know the first thing about car audio...but this forums been amaing! You guys rock hahatoo little port area can cause 3 things in 4th orders. massive port noise, less output, more controlled output.... usually all 3 happen at once for a new guy. not saying you couldnt do small port area but there is a fine line in small port area and a hole in the box

iggiafrica
03-30-2012, 02:15 PM
Lol i know what your saying... Im trying to stay away from pvc and just do slot ports...also from what i drew up its more of a labarynth design..do 90 degree angles effect anything? Also. If it started being 2", then the board was 4" from the side wall and went back to 2 wide and so on for 3 turns, what happens? Essentially a multi-width port i guess..any harm there? Or a snail shell box that hits 10x harder? Haha

iggiafrica
03-30-2012, 02:26 PM
I guess theyd be more 180 degrees

iggiafrica
03-30-2012, 04:47 PM
How different would it be building just a ported box? Is port tuning pretty much the same?

And another bandpass question: what happens when the drivers are turned around? (Magnet in ported area)

iggiafrica
03-31-2012, 12:37 AM
Is there anyway someone could help me out with all the winisd dimensions? Id really like to play with the different types of boxes..im off tuesday and plan on building. I plan to make a sealed, ported and 4th order for these 2 12s by the end of april... Winisd would be a HUGE help!

iggiafrica
03-31-2012, 06:46 PM
Well i finally got winisd to work, but i cant change the reading to SPL.. it says error something divided by 0..and im not sure why the line counts from like -30 to 0....what does that mean?

Kangaroux
03-31-2012, 06:56 PM
Mp3 files and the like measure volume in terms of decibels with 0dB being the loudest. I assume winisd adopted the same concept, though it's kind of a strange way of labeling the graph.

iggiafrica
03-31-2012, 10:02 PM
Well...i dont understand it lol. Id like to see the spl that my designs could potentially produce

iggiafrica
04-01-2012, 05:54 AM
Its been fun folks :) illbe putting my top 3 designs in winisd tomorrow and see what will work best for what i need. Ill be building on monday, wish me luck!