This is pissing me off. I just finished mounting my brother's sub (JL 12W3) to a box that I bought from DJ Sexay that he had made for himself but scrapped so that he could put in the W7. I used a fair amount of sealant around the edges, but I tried to be conservative so that it didn't spill over and make the thing look nasty.

Anyway, I hooked it up to his 400W kicker amp and was sorely disappointed. I had it in another set-up (granted in a box that was matched perfectly to the sub) where it was only getting 120W and it sounded better. Right now it's excurion is dramatic while the bass and volume are minimal. My first thought is that it's not sealed properly. Now, I'm really hoping that it's the seal around the subs itself and not somewhere else on the box.

I just want to make sure I'm not forgetting anything 'cause I really want to finish this soon so I can get to my own car. Any thoughts would be appreciated. Thanks.

 

It sounds like your barking up the right tree. Lots of excursion, good sealed box, and 1 sub. It has to be an air leak somewhere. The sub mounting surface is a likely culprit. Is the box finished in carpet or anything? Try using some closed-cell, self adhesive craft foam between the box and sub. Cut away the carpet under the sub if necessary

 

Yeah, that's a good point. I mean, I cut away the bulk of the carpet, but I left a slight ridge just to make sure that the baffle wasn't visible, and it doesn't take much to lose a seal. I'm gonna pop it out as soon as I find the time and really go over it meticulously.

 

Is it wired correctly

 

Yeah, checked that too. Used a multimeter on the speaker plugs and it shows 2ohms of resistance like it should.

 

How to you get your multimeter to read 2 ohms???

mine doesn't read the coil's impedence, just the electrical resistance through the coil which is 0.0 ohms unless the coil is burned out (open) . I don't think your coil is open, because the meter would read 1M..or "infinite".

my question is, how does your multimeter read the actual impedence at the coil terminals?? does your's have an extra option for this?

I have a cheapie digital multi-meter, it's a sears 982406 purchased for $65. it does the job though, one of these days I'll get myself a Fluke. (high end brand)

 

the impedance changes with frequency.. but usually if you measure resistance its pretty close to what the speaker should be. like, if its a 4-ohm speaker, you might get 3.2 ohms or something..

 

Really? The coil shouldn't register 0, that doesn't make any sense. It would register infinitely if you put both leads on the positive terminla or something, but if you put one on the positive and one on the negative then you should register the resistance of teh coil. If you don't, you have a short waiting to happen.

And I registered 2ohms because I hooked it up to the the "final product" terminals on the box with my coils wired in parallel. If I was to measure the individual coils, they'd register around 4ohms, like mud said.

 

I dont want to start an argument with anyone here, but nothing is making sense about this. ohms between speaker terminals is not ohms as in resistance even thoguht they both use the same word. this happens alot in the electronics/computer field and confuses the *&%^^ out of people.

ohms regarding impedence, is actually Xl or "inductive reactance"

this does involve frequency wich mudaholic pointed out, the formula for Xl or impedence of a coil is:

6.28(frequency)(inductance) = XL , epressed in ohms, like resistance but this same coil would have zero ohms of RESISTANCE and 4 ohm IMPEDENCE if it was a speaker coil we were talking about. the formula above, is universal and can be used to figure out the impedence of any coil.

I have no idea how frequncy can be determined in an audio circuit, but the bottom line is that a mutimeter is measuring resistance not impedence.....two completly different things

not all coils will have zero resistance, the ignition coils for instance, have a resistance. speaker coils don't typically have a resistance from negative to positive. there is absolutly no way that there can be a "short waiting to happen". I'm sorry, I didn't come here to argue, I have done this test on perfectly working speakers I have never once seen my meter read 4 or 8 ohms of resistance between terminals. I'm not saying I don't believe anyone here, but your multimer sure isn't reading resistance. I just want to know what multimeter you have and where you got it from. I would like something that can read impedence. there are capacitance testors, so I don't see why there cant be inductance testors.

if you don't believe me, switch that thing to the "diode tester" which is actually a continuity tester. (it is the option on the resistance scale with the music note and arrow) touch the pins together........you should hear an audible tone from the meter and see 00.00 on the display.....this is zero ohms resistance, current is flowing!! put one lead on each speaker lead, doesn't matter wich colors............same thing you will hear a beeeeeeeeeeeeeeeeeep and see the display showing 0.0 ohms current is flowing from one side of the speaker coil to the other, hold the leads apart and there is no tone and the diplay shows one million or infinite depending on the meter you have.