Hi,

I have a Kicker EX120 in a ported box powered by a small Sony mono amp, running off an Alpine CDE-9874E headunit. After maybe 5 minutes of use, the sub will just drop out. If I turn the headunit off and back on again, the sub will come back to life for a few minutes and then die again.

Whilst the sub is not working, the power lights on the amp are still illuminated. I have checked the wiring on the amp and looks well attached. I am thinking either the headunit has a fault or the wiring at the back of the headunit is loose?

Thoughts?

How is the sub wired up? OHM rating before hitting the amp?
Chances are the amp can't handle the sub and when the sub kicks hard the amp goes into protection mode
Turning off the deck and back on again is like a reset but wont fix the issue

Yeah it could be several things. Of course the power light may stay on but a protection light may come on also.

While stationary of course, hook up a smallish speaker at low volume and see if that cuts out.

I'm afraid you are going to need to do some more trouble shooting.

I don't think the coils of the sub will hurt it as it should be a SVC or DVC 4ohm woofer running off a mono.

Checked and double checked your earth points etc?

I'd guess at the amp cutting out as well.
is the amp hot? I believe there's a thermal cutout too.

Does it only cut out with high volume only, or low volume also?

i'm having issues with overheating with my kenwood at high volumes - thats why I asked for your sony one :P kenwood one just can't handle it

Cyber, where are your gains set?
Whats the model of the sub and Amp?
Will it run at low volume for a long time?
Does the amp earth to bare metal close to the chassis rail?
Is the Battery Negative earthed to the body bare metal/ close to the chassis rail?

In normal operation do you get a green light? and when it stops a red light light as well?

ok ok im not the best with audio electrical so let me get this out.

I believe gains are very minimal, maybe 2 on the scale out of 10?

It runs if I leave it on low volume, although i need to confirm this tomorrow.

The amp is earthed in the boot space to solid metal using 4ga

Battery negative terminal also earthed to the chassis using 4ga.

Ers helped heaps with the install of sub and amp, the rating of the sub is MUCH lower than the amp. Sub is around 250W RMS peak, and the amp is something like 400W RMS i think. not a very powerful setup at all and running at 4ohm IIRC. The amp does not get hot after hours of use previously, only just warm to the touch.

I will be checking earths tomorrow.

ERS is fairly fanatical about his audio, and I would assume his connections are good. Generally the auto cutout will activate with a lot of heat build up. But if its done fast enough, its possible that it will just feel warm.
@ 400 watt the small sony amp sound pretty big, like 400mm x 250mm. But that could be the peak.

I couldn't find the Subspecs, but kicker have an intro model @ 150 watts/300 peak.

If you get the chance run the amp in some else boot and see whats what. Thats if its under warranty.
It does sound wierd that at such low gains its cutting out. I hope the Amp aint fried, Do you know what blown capacitors look like, ( a small tin of beans pulled from the fire before they explode, or sometimes leaking a white or yellow goo.)
These Capacitors store power and feed it to the amp as required.

http://braineater.kicks-ass.tv/miscshite/vxcaps.jpg

hmmm I know the amp was once abused by Ers himself lol

His wiring was bloody top-notch to be honest so I highly doubt it would be that. I will take a closer look tomorrow. Sorry Dean the amp might be dead lol

But remember i did GIVE you the window surrounds hehe

:( Hope not - Maybe the HU is dead! :P

If that is the case, as mentioned hook up another speaker / sub.

Cooked subs can cause lots of issues. That would be my next point of call.

I feel so proud of myself right now, i fixed it!!! This electronica stuff isn't so hard hehe

The earth connector on the amp had snapped, so just needed to replace it :)

Thanks for the help guys, it also meant I actually tuned it all up a bit better. The gains were right down on the front and rear speakers so I pushed them up a bit and ITS ALIVE MWAHAHAHA

O.o So what snapped? The ring terminal or the ground wire contact?

the ring terminal. They dont like being bent 90 degrees

EDIT:just realised that the original problem has been resolved, so this is completely irrelevant for this case. But still, I'll let it stand just in case it helps someone else down the track. :)

The last time I had one doing that it was the sub having partially blown its coil.

It reduced its resistance from a rated 4Ohms down to about 1Ohm. At really low drives it was all good, but as power started beefing up, the amp would start cycling into (and out of) protected mode.

Best test is just to hook a multimeter up to the subs input terminals and measure the resistance through the coil. If the resistance is way lower than the sub is rated for; your coil has popped and you're over-loading the amp majorly every time you run it.

I am having some other issues now, can hardly hear the sub even after turning the gains up. Oh well, time for a new sub and amp!! Also, I have interference somewhere after fiddling with the earth from the amp :(