subs hitting wierd
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=86132
Printed Date: April 26, 2024 at 4:06 AM
Topic: subs hitting wierd
Posted By: oxygen65
Subject: subs hitting wierd
Date Posted: November 24, 2006 at 4:50 PM
i just installed 3 12w3v2's in a car running off at 2.7 ohms in a prefab ported box using a ma audio 401sx . when the subs hit the middle sub hits the hardest and the other two dont but then sometimes the subs on the side hit harder and then sometimes they all hit the same??? the only thing i can think of is that it is becuse the subs have a shared chamber for all 3 even though it is ported. so any help on this would be nice, thanx
Replies:
Posted By: master5
Date Posted: November 24, 2006 at 5:21 PM
If the subs are actually sharing the same chamber, and are recieving the same power, and are the same model sub and ohms..they should be hitting the same. Either you have a phasing problem, or the coils are wired wrong..or a combination of both. If you are 100% positive that all 3 subs are identical you can use a meter to see that each one is at the same ohms load. The use a 9v battery to check if they are in phase (they all move the same direction) when you send the dc voltage. I can't see anything else it could be after that other then a poor enclosure seal somewhere (leak), but if they are sharing the same airspace I would think they would all show the same effect together. -------------
Posted By: aznboi3644
Date Posted: November 25, 2006 at 12:53 AM
Agreed with master...to me sounds like a wiring problem.
Plug them into a wall socket and see if they all move the same direction...simple and easy test lol
Posted By: master5
Date Posted: November 25, 2006 at 12:57 AM
Funny azn..yeah they will move allright...out of the baskets..lol I have plugged speakers into the wall before...if you use ohms law you can see they are getting alot of power..well lets see... P=e2/r ok..so for a 4ohm sub....P = 110 x 110/4 P = 12,100/4 P = 3025W rms @ 60HZ yEAH i DON'T RECCOMEND THAT...LOL -------------
Posted By: master5
Date Posted: November 25, 2006 at 1:04 AM
oh he's at 2.7 ohms so closer to 5000watts rms...that'll do it
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Posted By: jvillefinest
Date Posted: November 25, 2006 at 7:46 AM
thats funny, before i even opened this post i knew it was a phase issue...just had this same issue the other night with my w6s battery test should prove this theory correct.... ----i like coleslaw----- ------------- 2007 Acura TSX
SQ setup in the works
Posted By: oxygen65
Date Posted: November 25, 2006 at 2:14 PM
ok so your saying its a phaze issue. there is a setting on my headunit were i can reverse the phaze of the subwoofers, i did that and it doesnt help any and i have no idea what you are talking about doing with a 9 volt batter, but could you explain it a little more so i can fix this problem
Posted By: aznboi3644
Date Posted: November 25, 2006 at 3:22 PM
You can't simply swith a flip and correct your wiring problem...you are gonna have to get your hands semi dirty and take all of the subs out and redo the wiring.
Click on the woofer wiring guide on the left of the page for help
Posted By: oxygen65
Date Posted: November 25, 2006 at 4:08 PM
well i took them out of the ported box and put them a old sealed box that i had layin around and they work fine now. the wirering was right on them i checked it like 6 times to make sure. i dunno i think there was somethin wrong with that box that i had them in. now i just have to build another box. could it have had somethin to do with the port that made the subs do that?
Posted By: aznboi3644
Date Posted: November 25, 2006 at 4:10 PM
Well can you draw up a picture of the box???
Posted By: xtremeimage
Date Posted: November 25, 2006 at 4:13 PM
if the boxes are not ported to correct spects , it can cause a problem , try using a program to tell you how to do it , i hear there are some good ones out there, i do a lot of book reading so thats how i do it , each sub must be in its own indipendent box porteded sealed from each other.
Posted By: master5
Date Posted: November 25, 2006 at 5:06 PM
Ok as far as phasing being the problem it is not about the subs being out of phase with the rest of the system..which is what that switch on the deck is for..it is the subs being out of phase with each other. However you seem to be pretty sure that they are wired correctly. So it is a problem with the box..I agree with xtremeimage there. But I personally have built plenty of ported boxes where mulitple woofers share the same airspace..there is NO reason this won't work...If it's built right. Any ported box built improperly will react unpredictibly, not give the best sound..and can lower the power handling of the subs causing them to blow prematurly. Now regardless of the subs being in the same space..or divided you need to take everything into account when building a vented box. The correct airspace..the correct port volume...well sealed and braced where needed. Otherwise expect problems like this or worse. There are some good programs out there that you can load in the T/S parameters of your subs..and it will instantly give you all the proper specs and if like my program gives you a cut sheet as well. You tell the program the type of enclosure (sealed, ported, bandpass, iso..anything basically). It even displays a graph predicting it's F3, output..power handling etc..really nice. -------------
Posted By: master5
Date Posted: November 25, 2006 at 5:17 PM
https://www.carstereo.com/help/Articles.cfm?id=17 If you go here you can use this "basic" calulator for a ported enclosure. You will need to enter some parameters which you should have or must get from the speaker manufacturer. You can determine the TS parameters yourself with some equipment but it's time consuming and not really nessecary for a typical install. Now if you are going to divide each chamber just enter "1" and build the other 2 chambers/ports indentical. If you wish to share the airspace enter "3" and it will give you the specs. Good Luck -------------
Posted By: oxygen65
Date Posted: November 25, 2006 at 7:00 PM
well it is a prefab box and i think there is something wrong with it but anyways i need box for 4 of them now but what kind of box building program can i get for free or cheap?
Posted By: master5
Date Posted: November 25, 2006 at 7:04 PM
the link I posted is perfect for you..and its free
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