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poor output from subbox with pictures

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=116623
Printed Date: March 29, 2024 at 12:02 AM


Topic: poor output from subbox with pictures

Posted By: eric21
Subject: poor output from subbox with pictures
Date Posted: September 30, 2009 at 8:12 AM

I built a ported box for 4 12" alpine type r's to go in the back of my crew cab pickup and the bass output is quite lacking imo. Each sub is getting about 750 watts each so 3000 total which should be plenty. Note that this is only for strret pounding and not SPL.
The enclosure is 8.5cu.ft. net and has a port that is 15" x 6" and 22" long. The bass is ok from about 25-35 hertz (still not impressive though) and all other frequencys totally blow.
I've tried the box pointed foward, back and up with the best results being from having the box point up.
I assumed that maybe my port was tuned too low so I made it 12" long instead of 22". It still plays about the same as before believe it or not.
I've noticed that the speakers quickly begin to stink and at many frequencys sound like they are playing freeair. So i'm thinking that I have too much port area for these subs (i know its only 90 sq.in.) but they sound like they need alot more back pressure.

Guys please take a look and see if you notice any places for cancelation or other flaws that might make this box sound so poor. Any design change ideas would be qreatly appreciated.
Thanks!!
Picture of box without speakers 

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Picture of inside the box

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Replies:

Posted By: ragsports
Date Posted: September 30, 2009 at 9:19 AM
One flaw i can see is that there is no internal bracing. For a box of that size you have to brace the walls of the enclosure. There is most likely some flexing going on here...




Posted By: eric21
Date Posted: September 30, 2009 at 10:29 AM

ragsports wrote:

One flaw i can see is that there is no internal bracing. For a box of that size you have to brace the walls of the enclosure. There is most likely some flexing going on here...

Yeah you are right about that, I got alittle lazy. After I figure out my new design i'm going to add a good amount of bracing. Thanks!

Now if anyone can see anyother problems with my port/box design please let me know! Thanks guys





Posted By: tommy...
Date Posted: September 30, 2009 at 12:14 PM
Sorry if this seems noobish...But the subs wiring was done correctly...?

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!




Posted By: eric21
Date Posted: September 30, 2009 at 12:16 PM

Thats ok, yeah I checked all the phasing of the woofers and even switched them to hear the difference and they are correct.

Thanks though





Posted By: icearrow6
Date Posted: September 30, 2009 at 12:40 PM
My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.

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Posted By: eric21
Date Posted: September 30, 2009 at 12:54 PM

icearrow6 wrote:

My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.

Do you think I may be getting cancelation because of the one common chamber for all the subs?

I like the idea of seperate chambers, do you think a 4" areoport per chamber would work ok?





Posted By: aznboi3644
Date Posted: September 30, 2009 at 1:27 PM
icearrow6 wrote:

My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.


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Custom Enclosure Design




Posted By: eric21
Date Posted: September 30, 2009 at 1:46 PM

aznboi3644 wrote:

icearrow6 wrote:

My vote is too big of a box. ~2.1 per woofer is too much in my opinion. I also vote for bracing or individual chambers. Try 1.5 airspace per woofer.. with the 12" slot port.

When you say 12" slot port, what dimension are you refering to?





Posted By: KPierson
Date Posted: September 30, 2009 at 2:00 PM
It's hard to tell from the pictures, but there doesn't appear to be any river rocks, moon rocks, pop rocks, or any other types of rocks in the box.

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Kevin Pierson




Posted By: tommy...
Date Posted: September 30, 2009 at 2:12 PM
Heamphyst said he had a bunch in his yard...Im sure he'll give you a great deal...!

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M.E.C.P & First-Class
Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!




Posted By: armymp90099
Date Posted: September 30, 2009 at 2:38 PM
ok this is most likely a dumb question but what do people mean when they talk about river rocks? ive heard it a few times here.

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-ETS-
Escape The Scilence




Posted By: haemphyst
Date Posted: September 30, 2009 at 2:42 PM
1: I can't see HOW that "sans drivers" picture works... Is that a picture of the bottom of the box, before the driver holes are cut?

2: BRACE IT! Those panels are HUGE, man! With panels that sze, no wonder you aren't gettig any output.

3: Common chambers are not a bad thing, necessarily, so IMO, that's not the issue. I do agree, however, that the enclosure is probably a little bit large-ish. Large enclosures will prevent you from achieving max output but it improves your extension.

tommy... wrote:

Heamphyst said he had a bunch in his yard...Im sure he'll give you a great deal...!

...smokin' deal, baby! Most look like doggie cigars, but you can have all you want!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: eric21
Date Posted: September 30, 2009 at 2:42 PM

armymp90099 wrote:

ok this is most likely a dumb question but what do people mean when they talk about river rocks? ive heard it a few times here.

Haha it was from another thread where someone said putting rocks in his box made it sound better, probably because it took up airspace. I wish i could just use some rocks haha





Posted By: armymp90099
Date Posted: September 30, 2009 at 2:47 PM
lol ok that makes sense now. maybe he could put some decals on the box to give it more horsepower too!

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-ETS-
Escape The Scilence




Posted By: eric21
Date Posted: September 30, 2009 at 3:08 PM

haemphyst wrote:

1: I can't see HOW that "sans drivers" picture works... Is that a picture of the bottom of the box, before the driver holes are cut?

2: BRACE IT! Those panels are HUGE, man! With panels that sze, no wonder you aren't gettig any output.

3: Common chambers are not a bad thing, necessarily, so IMO, that's not the issue. I do agree, however, that the enclosure is probably a little bit large-ish. Large enclosures will prevent you from achieving max output but it improves your extension.

tommy... wrote:

Heamphyst said he had a bunch in his yard...Im sure he'll give you a great deal...!

...smokin' deal, baby! Most look like doggie cigars, but you can have all you want!

The bottom of the picture is where the speaker holes were cut (where you can't see the port opening) sorry I could see how that would be confusing.

The output isn't nonexistant but sounds like garbage with most music. I have strong bass at 25 hertz and my car flexes really bad at that point but I loose everything a few hertz later.

I am going to brace it much better, do you think a seperate chamber with a seperate port per woofer my help my problems?

Thanks





Posted By: KPierson
Date Posted: September 30, 2009 at 3:48 PM
As long as you are using one amp to power all the subs I wouldn't worry about individual chambers.  It will strengthen the enclosure, but it won't be a requirement.  A box is all about size - determine exactly how big the box needs to be and the exact port size and build it.  Anything past 10% off is going to give less then optimal results.

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Kevin Pierson




Posted By: eric21
Date Posted: September 30, 2009 at 3:53 PM

KPierson wrote:

As long as you are using one amp to power all the subs I wouldn't worry about individual chambers.  It will strengthen the enclosure, but it won't be a requirement.  A box is all about size - determine exactly how big the box needs to be and the exact port size and build it.  Anything past 10% off is going to give less then optimal results.

I'm running two clarion 1550watt amps, so should I divide the box in half and reconfigure the port?





Posted By: KPierson
Date Posted: September 30, 2009 at 3:56 PM
I would divide it up then.

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Kevin Pierson




Posted By: icearrow6
Date Posted: September 30, 2009 at 4:25 PM
[QUOTE=eric21]
"I'm running two clarion 1550watt amps, so should I divide the box in half and reconfigure the port?"

.... I found the problem?
I think u are running these speakers in STEREO, on a single chamber....
You have the left channel split to one amp, and right channel split onto the second amp? If you want to get ALL the woofers to work in unison you need to run the as MONO. Take one of the RCA's preouts from the deck and split it. you'll drop a little in voltage, but you'll get MONO on BOTH amps. Try this before you go and make another box altogether... Bracing the box though is a given.

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Posted By: icearrow6
Date Posted: September 30, 2009 at 4:26 PM
KPierson wrote:

I would divide it up then.


^^ PRO ^^
posted_image

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Posted By: eric21
Date Posted: September 30, 2009 at 7:09 PM
icearrow6 wrote:

[QUOTE=eric21]
"I'm running two clarion 1550watt amps, so should I divide the box in half and reconfigure the port?"

.... I found the problem?
I think u are running these speakers in STEREO, on a single chamber....
You have the left channel split to one amp, and right channel split onto the second amp? If you want to get ALL the woofers to work in unison you need to run the as MONO. Take one of the RCA's preouts from the deck and split it. you'll drop a little in voltage, but you'll get MONO on BOTH amps. Try this before you go and make another box altogether... Bracing the box though is a given.


Thanks for the detailed response, I wish thats what it was though. I previously had 4 sealed 15" woofers off of the same two mono block amps and they slammed really well with the exact wiring configuration. I was just thinking a properly tuned ported box should outpreform a sealed box thats why I went with this box. I don't mind building another box, I just wanna get it right this time. I'm gonna divide up the chambers for sure, but just need to figure out the ports. Thanks for all the responses so far!!




Posted By: eric21
Date Posted: October 01, 2009 at 7:35 AM
Ok here's an update - since i'm gonna build a new box anyway, I made a port insert that had an opening of 12"x4.5" and 10" long and put that in the old port hole. The difference was huge, the speakers kept in control much better, the voice coils didn't stink as easily and the output was alot louder.
Then after I added some wood to the inside of the box to lessen the volume and that helped too by seeming to make them sound more musical over a larger frequency range.
Still one thing I noticed is that the 2 outtermost subs seem to be moving more then the inner 2 subs, so i'm guessing there is some big pressure differences in the box because of the position on the port.




Posted By: jeffchilcott
Date Posted: October 01, 2009 at 7:59 AM
Besides the bracing issue, I am almost wondering if you are having unequal loading issues.

With a box that large I dont like to have a "center" port.   I typically use a narrow but very wide port...I.E 2.5x36xport length.

I have had much better results with that, and if the port is from 1 wall to another also add some bracing in itself.



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2009 0-1000 Trunk WR 154.0DB 2009 1001+ Trunk WR
2007 USACI World Champion
2007 World Record
2006 USACI Finals 2nd Place




Posted By: eric21
Date Posted: October 02, 2009 at 7:21 AM

jeffchilcott wrote:

Besides the bracing issue, I am almost wondering if you are having unequal loading issues.

With a box that large I dont like to have a "center" port.   I typically use a narrow but very wide port...I.E 2.5x36xport length.

I have had much better results with that, and if the port is from 1 wall to another also add some bracing in itself.


Thanks Jeff, I learned quite a bit from the build screw up. I've decided to do 2 chambers with the subs in a straight line along the bottom of the box with a 6" areoport centered above each pair of woofers and add some bracing. Does that sound like it should work alittle better?

Once I get my ports in the mail I show my build, hopefully this one doesn't suck as much.





Posted By: eric21
Date Posted: October 13, 2009 at 7:44 AM

Ok, I re-built my box and I gotta say what a difference. The new spec's are 2.1 cu.ft. per woofer, 2 seperate chambers with half dividers in between each woofer for bracing/loading. Each chamber has 1 - 6" areoport 10" long and I used a double baffle this time. It's pretty intense from 30-45 hertz. Thanks for all the advise.

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Posted By: blackcivichatch
Date Posted: October 13, 2009 at 7:48 AM

Looks good man. Where did you get the ports at?



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UNLABELED Custom Car Club President




Posted By: eric21
Date Posted: October 13, 2009 at 7:55 AM
blackcivichatch wrote:

Looks good man. Where did you get the ports at?


I got them at precision sound products (https://www.psp-inc.com/). They are pretty nice quality but cost $40 a port, I think it was worth it though.





Posted By: boogeyman
Date Posted: October 13, 2009 at 8:29 AM
 Looks good....how does it sound?




Posted By: eric21
Date Posted: October 13, 2009 at 9:09 AM

boogeyman wrote:

 Looks good....how does it sound?

Thanks man, well I went from 4 - sealed 15" woofers in the crew cab of my pickup to the 4 - 12" ported and it sounds louder to the ear but i'm sure the spl isn't as high. The low end bass from these woofers in this box is really surprising (sub 40 hertz) and sounds good on most music. They really lack though on 55 hertz and up though, but overall i'm pretty happy with the results. They can hurt my ears pretty good and the bass really messes with my vision when driving so i'm assuming its pretty loud.





Posted By: babydaddy
Date Posted: October 17, 2010 at 6:52 PM
try making the port come out the side of the box.

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KyleRozema




Posted By: KarTuneMan
Date Posted: October 20, 2010 at 10:40 PM

KPierson wrote:

It's hard to tell from the pictures, but there doesn't appear to be any river rocks, moon rocks, pop rocks, or any other types of rocks in the box.

I remeber THAT one.... a true 12 volt "classic"



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