help please

[btnhfan]

wow. i have lots to say so please take your time to read it and help me out.

so the other day, my subs cut out. this is after having them running for 3 months now. i turned the volume up and it came back on. the next day, it cut out again and didnt come back on. i thought a wire came loose so i re-did the speaker wiring and during that, the + and - accidentally touched and sparked. anyway, nothing was working out, so i got a multimeter and tested the ohms at the sub and the amp.

i cant get reading on either really, or if i do it doesnt make sense. the amp is gettin a constant 13v throughout all of this. so i took the subs out of the trunk and again tried to get a reading. but i couldnt get anything, so i tried to undo the bottom part were the wire goes, and then i heard a hissing noise. what happens if my mm10 loses its airtight seal?

o and i also upgraded my ground wire finally, from 8 to 4 guage, cuz my power was 4 guage, and i never had time to do it

so is my amp or subs blown, and what about the seal?

i have 2 mm10's and a fosgate 1001bd
please help!

[neomagus00]

when you say you took the bottom part out, what do you mean? bottom part of what?

so you tested the +12V line, and got 13 volts... that's good. did you put it between the + terminal of the amp and the + terminal of each sub? that is, check each sub individually for ohms and volts... it should be around 4 (actually probably more like 3) ohms, and if the amp's going full power, maybe 30ish volts? what are your results for each sub?

did you check the fuse(s) on the amp from the spark? and the seal on the mm10's shouldn't just go...

oh, just for reference, when you're working on the system, you should unhook the +12V lead from the battery; since you have a fuse there (right?) it's easy to do

[btnhfan]

yea i forgot to unhook the battery, but i did after that. the bottom part that i tried to take out was at the bottom of the sub, where the terminals are. i did put it there. from what i remember, it was lower than 30v, in the 20's. and i didnt get anything on the ohm reading. like 1 or sometimes negative.

[neomagus00]

okay (yeah, you do kinda have to have the battery connected to get valid readings, huh?)... that strange reading of ohms sounds like a short through the sub. i forget what it's from - hey someone else, this is where you chime in - to confirm, hold the two multimeter leads together, and you should get a similar reading.

is this on one or both subs? and the subs are playing as you do this, yes?

the voltage in the 20s is fine, btw

[btnhfan]

subs are not even playing. and it is on both subs.

[neomagus00]

okay, let me get this perfectly clear - you have power, ground, RTO, and RCA's hooked up to the amp. you also have one subwoofer hooked to one channel of said amp. with music playing on the HU, there's no output from the sub? and when you keep this setup and change subs, same thing?

[btnhfan]

correct.

[neomagus00]

ouch... sounds like you blew both subs... i assume that you were running them in parallel, right? which still gives you 375 W/each, so you're well within their powerhandling capabilities.

do you have access to another amp to try them out? access to another speaker (any kind) to check the amp? did you try the leads across the sub's terminals (the multimeter should be able to put out its own power and test the resistance across the sub)? all this is just to make sure that your subs are toast, cause it could be something else i'm missing.

[fairlynew1]

heres a tip someone gave me to test the subs. dissconnect the speaker wires from the amp, so it is still hooked up to the sub, and take a 9 volt battery, hook up the pos and neg, if you here a noise coming out of it, sounds almost like a small, faint pop. if it makes that noise, theyre still good,

[btnhfan]

i was running the subs so that they each ahd 2 ohm and 500w rms, like it reccomends. ill check that 9v battery and try to get another sub or amp to test. thanks for the help.

[neomagus00]

um... the mm10 have a rec'd rms of 400 W, and you're not getting any more than that out of that amp (unless it's severely underrated and you're pushing it to distortion).

yeah, try the 9v thing, you should see the cone move too... (get a new 9v to be sure)

[btnhfan]

then y does it say 500w rms on the subs?
the brith sheet on the amp says 1097 at 2 ohms, so then im giving it a lil over 500w to each sub wen i wire them to 2 ohms.

http://www.polkaudio.com/car/specs.php?name=mm10

[neomagus00]

a) my bad, it is 500
b) damn, that's a lot of power... and if you want to hear about the effects of overpowering the momos, talk to cody (exalted512), he'll tell you many many stories...

yeah, try the battery thing, and we can go from there... it sounds like both subs are toast tho... did you break them in properly?

[btnhfan]

im going to try the battery thing right now. i broke them in properly, just as the manual said. its been fine for 3+ months now though.

[btnhfan]

welp. the subs are blown or something else is wrong with them. i borrowed my friends mm12 and tested it with the battery and it popped, while my subs did not. then i hooked his up to the amp and it worked. what can i do now?

[neomagus00]

they may be covered under warranty... as to why they blew, no idea...

[btnhfan]

thanks for all your help.

[btnhfan]

o and one more thing. is this covered under polk's warranty?

[MacLeod]

This is concerning me. We seem to keep hearing reports of blown Momo subs. Im wondering if Polk is having quality control issues with their subs? Granted, virtually all the complainants were overpowering their subs but not by much and most manufactuers rate their speakers well below the actual limit for safety reasons. Hmmmm..:confused:

[neomagus00]

well, in the vast majority of cases recently, it's due to significant overpowering; some, like cody's most recent, it was only by 10% overpowering; and at least for this one we have no clue what caused it. i'm guessing only one sub went (cause as soon as one goes, the other gets the full amp input and blows up). but why?, we ask... overdriving the amp? a wire came loose on the second sub, driving the first with the full voltage of the amp? who knows...

the parallel wiring bit throws a new set of complications into the picture; now, if it was a 1 sub system, i'd agree wholeheartedly... as it is, i agree maybe 65%-heartedly :p...

[btnhfan]

what were the otehr cases of blown subs? cuz i might have been over the limit by like 30w or less. and it was always on a fairly low volume. the subs blowing perplexes me.

[neomagus00]

yeah, in your case i'm totally flummoxed... check all your wiring, just in case; not only the way it's wired, but also the physical state of the wires; i.e. are there cuts or gashes, or, if they're crimped anywhere, could the two wires of a pair be touching there, etc.

[exalted512]

my bd1000 was rated at 1236 watts and i blew my first set of momo's while running them off of it...it was clean power though
i dont run my subs to distortion, or at least it wasnt audible and i have a really good ear for that kind of stuff
ive blown my momos from anywhere to 75 watts over to 115 watts over
they work great and never show signs of distress then...bam...
you sparking the wires mightve caused a huge surge and thus blowing the speakers...that gets my vote
-Cody

[neomagus00]

assuming there was still a sub in the circuit when the wires sparked

[btnhfan]

there are no wires there any more, they werent touching at all. they were on opposite sides of my trunk basically. is there a way i could tell what actually happend to them?

the spark happend after the subs stopped working, and the subs werent even hooked up to the wires when they sparked.

[neomagus00]

damn, i thought he was on to something... i have no idea whether you can find out what happened or not, maybe ask a local shop?

[exalted512]

something might be wrong with the amp and it mightve sent a surge to the speakers
ummm
your fuse wasnt blown correct?
push your speakers in really fast...does it sound like sand paper or a spring or something?
last time i blew mine thats what it sounded like and i had(im guessing) fried the voice coil
the other 4 momos i blew were still making sound
have you checked the leads both on the terminal and where they connect with the cone?
the tinsel leads were a big problem on the original momo's, havent heard of a problem with the new ones--but worth a look--i had to repair the tinsel lead on my mm6 midwoofer
-Cody

[neomagus00]

i vote exorcism, it can't hurt :p

[AustinKP]

Originally posted by neomagus00
(cause as soon as one goes, the other gets the full amp input and blows up). but why?, we ask... overdriving the amp? a wire came loose on the second sub, driving the first with the full voltage of the amp? who knows...

the parallel wiring bit throws a new set of complications into the picture; now, if it was a 1 sub system, i'd agree wholeheartedly... as it is, i agree maybe 65%-heartedly :p... Neo, I don't think this could happen. As soon as one sub blew, the amp would be seeing twice the impedance, thus it would only be giving half the watts to the single sub. In other words, two 4ohm subs in parallel would be 2 ohms, thus 1000 watts. If one blew, it would just be one 4 ohm sub immediately receiving only 500 watts. That's my theory...

[exalted512]

Originally posted by AustinKP
Neo, I don't think this could happen. As soon as one sub blew, the amp would be seeing twice the impedance, thus it would only be giving half the watts to the single sub. In other words, two 4ohm subs in parallel would be 2 ohms, thus 1000 watts. If one blew, it would just be one 4 ohm sub immediately receiving only 500 watts. That's my theory...
hes right...itll put the impedance back to 4 ohms and the amp puts out 500w @ 4 ohms
-Cody

[neomagus00]

yeah, you guys are right; i didnt think about how the impedance would change when one sub blew. man, that's 2 biggies on this thread for me.

so that's pretty strange, to get both subs blowing at the same time then; maybe it's the amp, like cody said; is it still under warranty, maybe you can exchange it, just in case?

[subman32]

battery idea is a good one..... i use it all the time for proper wiring. but dont do 9v or else you could possibly blow one. keep it around a AA or a AAA. learned from the 9v by experience

Garry

[btnhfan]

i love polk. they said because it is unde warrenty they will replace them. all i have to do now is find my sounddomain receipt.

[exalted512]

i, for one, am extremely fond of Polk's return dept.
-Cody

[fairlynew1]

why would you use a AA or AAA? their volatage is like 1.5 or so....you would want something closer to 12 volts

[subman32]

i'm talking about testing the sub for proper wiring or if it is recieving power. all you need is that little movement or pop. AA and AAA are just enough for that.


Garry

[Buff013085]

same thing happened to me except i only have 1 mm10. i am only giving it 300 watts and i have had to send it in to get repairs 2 times. this time i am selling the sub. i have never had this much problem in less than 7 months from a sub ever.

[LittleCar_w/12s]

You are all WRONG! WRONG,WRONG, WRONG!!!!
Nah, I'm just kidding...
My question is: what does your meter read for resistance (ohms) for the sub when you have the leads connected to the sub wires, and the wires only connected to the subs?

Here is a guide to troubleshooting subs:

GIVEN (stuff to keep in mind):
>>Digital meters sit and give random readings with nothing connected (inf. ohms) and Analog meters read at infinity.
>>Digital meters will read 0.04-0.6 ohms to be in-precise when connected, this tends to be the impedance of cheap test leads. and Analog Meters tend to be adjusted to the leads attatched and will read 0 ohms

IF the readings are:
(1)>>0 ohms when connected to the sub wires.
(2)>>infinity ohms when connected to the sub wires.
(3)>>High reading (ie. 500-10K ohms)
(4)>>1,2,4,8 (+/_ 0.3) ohms when connected to the sub wires.
(5)>>0 - Infinity depending on how the box sits, or moves.

THEN:
(1)>>Yes, you have a short, if it does not void a warranty, test the sub directly to the driver. If same, the sub is shorted, if different, your wires are crossing somewhere.
(2)>>You have an open, test driver directly, if different, the wires are to blame again.
(3)>> Check at driver, if the same, your coil is definitely fried. In this case, you will normally still get low sound from the driver, unless the coil is stuck.
(4)>>Seems like the coil wire is good, The coil may be stuck, try pushing the sub in a little to un-stick it.
(5)>>Definitely a wire poblem, check the wires in the box, also the tinsel leads from the cone/spider to the driver's terminals.

Remember, your wiring may have a short in it from melting together inside or from a cut or cross, especially if there short-circuit run through the wire at any time.