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Discussion Starter #1
so ive done some research and read about bottoming out subs and what not. i have done it before several times and i dont understand why. i made my box myself but with the manufacturers spec's. its a 12" power acoustik MOFO series sub.
here are the specs for the sub and box
2400 watts power handling
1200 Watts RMS
270 oz . magnet
3¡± BASV/Kapton Hybrid 18 AWG Voice Coil
SPL 90 dB
Fs: 36.7 Hz Vas: 0.73 cu.ft. Qms: 5.34 ? Qes: 0.36 ? Qts: 0.3363
Xmax: 0.7"
Sealed box: N/A
Ported box: 2.4 cu..Ft.
Tuning: 40 Hz
Port size: 3¡± (dia)x 6.75¡± (length)
# of ports: 2
Mounting Depth: 6.75¡±

i built the box to exact spec except the ports at 8.25 inches long now because a box port program told me to do so haha. the fact is that i beleive there is some kind of error with the port sizing because if the sub is bottoming out then it has to be having too much port area to push the air through. or i am just putting too many watts to it. yet i am running a power acoustik bamf 2000/1d amp which puts out (supposedly) 1200 watts rms which the sub can handle fine. ive heard people going well over that. anyone have any ideas of what i should do?

another sort of related question is that i took the sub out of the box to check it in free air and here is a video of what the noise it is making..by the way the voice coil has some sort of alluminum add on that goes to the dust cap to dissipate heat quicker which may be the noise im hearing but it has just broken off the main part..let me know what you think i know your awesome.
YouTube - Sub Problem
 

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either your voice coil is ****ed or you need a subsonic filter on your amp to prevent said bottoming out or you are driving it too hard

and power acoustik = :(
 

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Sounds like the former is scraping the pole.

Did the sub get dropped or have evidence of being dropped?
 

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Discussion Starter #4
Sounds like the former is scraping the pole.

Did the sub get dropped or have evidence of being dropped?
the only evidence of some abuse is when it was shipped from me from someone who used it lightly, i noticed that four of the basket braces near the mounting rim were cracked...it didnt move it very much but they were cracked and one broke off completly from the other part but was about 1 mm away from the other. i used jb weld to fix it since i thought they didnt make them any more. could that mess with the former and pole?
 

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I think you have your answer....and a bad sub.

When the frame is fuc ked up ....forget it.

Just get something else.....at least you could get a decent sub this time around.

I'm sure you'll get a few ideas around here.;)
 

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Discussion Starter #7
damn. well i will just use it till it finally gets put out of its misery i guess because it works fine when its in the trunk and the trunk is closed...but when its open it is just rattling like crazy and it sounds like crap.

someone got a suggestion for a sub with good travel...more than .7" like this one. haha i love subs with good travel.

anyone want a custom box made to the spec above? let me know :)

the ports arent 6.75 inches long though. they are roughly 8.25 inches long and the tuning is like 39.5 Hz dont ask me why i just did the math
 

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Discussion Starter #9
**** Austin, My money is on it's no good to you now:(

Sorry man.
ITS ALL BECAUSE OF THAT GROUND WIRE!! LOL jk its been doing it for awhile now. that sucks i will try to find another one or something. = [

umm my budget is probably no more than 200 for a sub. if i have to spend a little more then thats fine
 

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Discussion Starter #11
I am selling my box with 2-10" 1st gen. Ascendant Audio Assassin's


You can find my ad here, Must go now, complete car system

To see what I am selling. I'll sell the subs and the box to you for $180.00
eh sounds like a very good offer but im looking for a 12 to replace this one in the same box if possible. this box took me a long time to make and i dont just want to scrap it. thanks for the offer though :) and plus i dont have a whole lot of money to spend on it right now.
 

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I can't see that video but if it's the MOFO series with the blue metal-looking star thing for a dust cap, those tend to come loose. When they come loose it will sound like the sub is squeeking or prematurely bottoming out.

*edit* Yep, those are the subs. You may not be able to see it come detached from the cone while pulling on it, but odd are that's what is going on. A friend of mine went through four MOFO 12's a long time also with the same problem in all of them. He switched to our Mag v3's and he never had any problems with them. Now he runs two Nightshade 15's in a BIG box with lots of batteries and power.
 

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Discussion Starter #15
I can't see that video but if it's the MOFO series with the blue metal-looking star thing for a dust cap, those tend to come loose. When they come loose it will sound like the sub is squeeking or prematurely bottoming out.

*edit* Yep, those are the subs. You may not be able to see it come detached from the cone while pulling on it, but odd are that's what is going on. A friend of mine went through four MOFO 12's a long time also with the same problem in all of them. He switched to our Mag v3's and he never had any problems with them. Now he runs two Nightshade 15's in a BIG box with lots of batteries and power.
wow that sucks. those subs and that design seem pretty cool. the point of the metal dustcap did seem to work since it got really warm when i used it a lot. oh well so much for me getting another one of those lol
 

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Discussion Starter #16 (Edited)
just for kicks, you could try and manipulate the gap on that sub.

mount it inverted, and take a couple of pieces of 2X4 to make a simple lever, then wedge a tire iron under the magnet and "GENTLY" pry down, while the sub is just barely making the noise, (low power, low frequency for stroke-age) going around the circumference of the magnet, until you find where de-stressing the frame gives the quietest play.

then comes the tricky part:

find a way to keep even pressure on the frame, while squishing epoxy putty into the tiny crack that develops between the magnet top plate and the frame, so that the gap is permanently moved into a better alignment.

it's a blowed sub, so before you finish it off, (and wear down the coil to a short) you might find that a little experiment lets you keep wangin' that puppy for a bit longer...
oohh i might try that haha. when it was doing the 1 hz i was holding the cone while it was moving and it seemed quieter in some areas than others so i might try that. so your saying bend the framing? i think i know where i should do it which is where the frame broke. here are some pics showing the break. it was shipped in a crate that it sat in and it probably slid around while being shipped...god damn ups probably throwing it around.
 

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After considering all of the evidence, I'm going to have to side with shadowfactory. That driver is just not very good, broken or working.

Maybe you should grab a DIYMA 12 while you still can.
 

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Seeing what he had, I have to highly disagree with the DIYMA suggestion. I wouldn't recommend any SQ driver to him actually (no Mag v4, IDQ, MAX, W6v2, etc). With a big ported box and 1200 watts from an amp labeled a 2000 watt, none of those drivers will hold up very well.

PS: That cracked frame will definitely make noise while playing. The dust caps on those can be problematic, but yours is clearly the frame. That would explain the squeeking noise. Think about the noise that metal on metal makes when it just barely moves - squeeking.
 

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Seeing what he had, I think this is a great opportunity to introduce him to a quality piece so that he could very clearly hear the difference between the two. If he buys two with his $200 budget he could just use caution when setting his gains and using the volume knob.

OP, would you like to have great SQ with respectable output?
 
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