SOULMUSIC

iTrader: (8)

I reconed the sub I blew last week and while it was curing I burnt the other subs coils. WTF? I'm sooo pissed

I'm gonna assume I had some clipping issues, not a bad ground as I thought before. Seem more likely I guess?

When the last one blew we thought we had a low voltage issue also (from the digital cap readout, it was just barely above 10 v when we checked. The subs performance declined over a five minute period then it blew.

This time however , no voltage issues ..12+ ..there was no audible clipping at any point, nice clean bass to our ears. The bass just cut out like someone pulled an rca. After touching the cone we knew it was the sub ..F'ing HOT!! The amp was cool though

So.. Does it sound like a clipping problem? Anything else I could offer up ito help diagnose this?
Please can someone help me with my math to set the gains with a DMM?
I just can't figure the numbers out properly

Sub is 1500 rms /amp rated 1k at 1ohm(does 800 though) / 6 volt inputs on the amp/ using a AC Matrix line driver .. I'm lost
MATHHHHHHHHHH arrrgg

PsychoAcoustics Canada

iTrader: (3)

improperly built box, poor cooling, distortion any of these could contribute to it

madwarrior

iTrader: (3)

did you not just build a new box for those subs? if you did i would have to go with the box. not enough ventitlation. i know some of my older subs in built boxes would starts to go quiet cause lack of air to the sub. but they never blew.

Soundigital

iTrader: (1)

when the performance declines is because the coil is so hot that the Re went to a high number, like 2x the inicial value and then you get half of the power. At this point you should shut it down and check.

Do you really need the line driver?

madwarrior

iTrader: (3)

Could the line driver have something to do with a burnt coil?

SOULMUSIC

iTrader: (8)

murilo- our HU is a low end Soundstream monitor, I don't have the voltage output numbers right here, not great though , also the RCA's are 20 ft to the amps in the van, if that makes a difference
It seemed like we were't getting any volume regardless of the gain setting before we used a old Phoenix gold tld22 LD, the LD seemed to fix it
We upgraded to a Matrix when we switched to using 3 amps and we figured we needed the channels
...we've used LD's for years because we always buy cheap headunits..I know i know..
So I think we need one, but hey, I made my $600 subs last 3 weeks, I'm OPEN to anything.
I just got a DMM, so I can check some things now I guess

I think I figured out the voltage numbers to set the gains with a DMM.
Came out to 28.28 v
If it is clipping alone, would setting them below this number unsure it's not clipping?

MW- No I bought the box, its the amp rack I built onto/around it I just finished.
I really hope its not the box, wait till you see it, you'll understand why I don't want to replace it yet
It is on the small side for the subs though, you and PA could be onto something shoulda gone to 2.0- 2.5 per sub, but space is an issue.

Maybe strap the amps and run a single 12" in a BIG ported box...would be about right number wise.. 1500 sub/1600 wrms strapped..

OOOh I just remembered, when the first one blew it was superhot and the other one wasn't, so perhaps that changes the problem being the box? Should they both not be hot then? The gains were matched by sight, so not even exactly . but the other sub should have been running a little hot too, shouldn't it?
The subs are in separate chambers with a shared central port

Man, I'm fricken scared to try again, the only "good" sub I have right now is my FIRST recone!! If I fry that , I'm stuck with a couple of 300 w RE's for the summer .. untill I can recone again or just get different subs..I'm so frustrated

Soundigital

iTrader: (1)

Yes, it is a good way to clip a sine wave, of course the filter on the amp's input will smooth the square wave but still it can be a reason, it can overdrive the amp.

SOULMUSIC

iTrader: (8)

The "overload" light on the Matrix must mean clipping, a least that what I assumed.

I tried to set it so the yellow "overload" light would only come on for a split second on the biggest bass hits. Too much still I guess huh.
Thats probably the flat spot(clipping) on the wave I've seen while watching vids with oscopes ?
Lesson learnt.

Would it be better to use the LD set high and the gain on the amp low, when setting voltage with the DMM ?
Or the opposite, less LD more gain?
Does it make a difference ?

Gonna put the box back in the van tomorrow, just have to decide if its 1 amp at 1 ohm with 1 12"
Or 2 amps at 2 ohms on 2 12s"

Gonna set with a DMM either way, I hope I have it figured right ????

Should the subs be plugged in the the amp when setting the gain or not?
I've seen too many conflicting stories to understand the difference..

JohnVroom

This is what is most likely causing it, though a defective run is possible (improbable)

in addition to the quote below you could be clipping the input of your amp (putting too much voltage into the amps input for a given gain setting). On your owners manual you see variable input voltage ratings for your amp (lets say 1v to 4v) this corresponds to your gain setting, when the voltage output of your line stage exceeds the voltage that the amp can take the input is simply clipped off at the max and the sound of a woofer with a clipped output commences (SO even if your line stage isn't clipping your amp may be clipping due to excessive input voltage)

Dukk has said this before and I have too any HU can drive any amplifier to max output without a line driver

bottom line in all this is WHAT CAUSES A WOOFER TO OVERHEAT AND FAIL? too much power, too little cooling

and the problem here is you dont recognise when your woofers distort (it may be easier for you to note when your tuning the volume **** up when it stops sounding good or it stops getting louder even though you keep turning up the volume ****)

SOULMUSIC

iTrader: (8)

Dont' recognize distortion?...ouch dude..
Maybe you could recommend a hearing aid?

the amps have 6 v inputs and the matrix is 5v pr channel, probably not that I suppose.

Just in case it is the box itself(lack of cooling) we're gonna put the RE's in and run with them for now, they ran flawless in that box for weeks, and we had set the gains using the same flawed method.

Thanks for all the input guys

Here's the burnt coil