Amp is going into short circuit mode

Hello,

I need some help with trouble shooting my system set up.  The problem that I have is with my Clarion APX4360 amp which keeps going into a short circuit protection.  The amp is rated at 4 x 90W at 4ohms, and I am running 4 focal polyglass components which are rated at 75W nominal, 90W max and these are 4 ohms components.  The volume on the HU goes from 0 up to 33.

Here is where it gets interesting:

When I play songs that are recorded well, ie clear, good dynamic range, no background noise the amp short circuits at a volume of 26,  when I play a song that is not recorded as well and it shorts at around volume of 29 and sometimes around 31.   In either case it seem to short itself when there is distortion starting to enter the speakers.   Once I put volume down for it starts to work again within few seconds.   I know that the Amp is not overheating, because it is not even warm to touch, and also it has a build in diagnostics and it show as short circut when it shuts down.  Overall the system does get lound, however I can sit in the car and listen at full volume without any problems, a bit disapointed becase I was told the the focal speakers get very loud and that I would not be able to sit in the car.

I just want to figure out why does this amp shor circuits?

Is it possible that the amp can sense the distortion in the speakers and shut down?  I have never heard of such feature on an amp.

Is it possible that the speakers itself have some sort of a distortion protection and create a short circuit to shut the amp off?  I have never heared of such a feature in speakers as well.  I know these are good speakers but still...

Is my amp simply not good enough for the speakers?

Any suggestions, or advice please let me know.

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2006 Jetta
Clarion MAX675VD HU
Clarion APX4360 & DPX1800 AMP
Focal Polyglass all around
2.5 Farad CAP

Sounds like your amp gain is too high or at least one of your speakers or speaker wiring is shorting out.

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So it is possible for the wiring to short out onlu at higher volumes?  I though once a wire is shorted it is shorted and that is it.

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2006 Jetta
Clarion MAX675VD HU
Clarion APX4360 & DPX1800 AMP
Focal Polyglass all around
2.5 Farad CAP

Did you completely re-wire the system , or are you using the factory wires to the speakers??

If using factory wires still, definatly run some new wires direct from amp to speaker.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

I have been told that the factory wires are OK for up to 600watts of power, I am only running max. 90watts.  Considering my AMP gain is only at 1/5 gain I am probably way under that.  The way I have it set up is from the amp to behind the HU is a thicker aftermarket speaker wire (16GA) and then I connected it to the corresponding speaker wires from the cube that is behind the HU(The stock wires are pretty thick maybe not 16GA but they are up there).  The reson for this set up is the way WV designed doors in these cars there is no access to wires by removing the inside door panel.  I would have to remove the outside skin to get access to the speaker wires and any other wire.  Also to run the wire through the rubber gourment is also impssible because it is an actual connector with no room for extra wires.  So I was forced to use the front part of the factory wiring.  It is also strange that no one else with upgraded system in a golf or jetta has this problem.  I am starting to suspect faulty Amp, or fauly speaker crossovers that are causing this. 

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2006 Jetta
Clarion MAX675VD HU
Clarion APX4360 & DPX1800 AMP
Focal Polyglass all around
2.5 Farad CAP

first of all I would like to say that vw is evil but that set aside I was working on a car with simular problems and I was considering it would be a battery ground wire issue maybe there is corrosion and it simple is not putting out the amount of amps it should.

This is simple....

take the speaker wires off the amp and meter each pair one at a time and VERIFY that each set is 4ohm +/- a few tenths. If any are measuring low there is a problem with that speaker or the terminals/wires.

If all meters good check for a possible shorted speaker wire by setting the meter to continuity or resistance and place the negative probe to ground and probe every speaker lead one at a time with the other probe.  If you get ANY reading from chassis ground to a speaker wire...you found the culprit...repair as needed.

If you do not have a meter or know how to use one you can do it the "ghetto" way and just hook up one speaker at a time to the amp...the speaker that causes the cutout is the culprit.

If all checks out well with ohms and no shorts..you have a bad amp.

Do this and post back so I can say..."I told you so"  lol

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I've had speakers that read alittle less (i,e should be 4 and are reading 3.7) than they should and they have worked fine... I am guessing even if they are the same speakers they can be slightly different because of production.

"4-ohm" speakers will almost always have DCR less than 4-ohms since speakers ar rated at their nominal impedance, not at their resistance.  Unless they are open or completely shorted reading their DCR may or may not tell you anything useful.

If the amplifier gain is set correctly speakers can short out at higher volumes for a couple of reasons, including over excursion (try adding a high-pass filter to them at around 100Hz) or in some designs the tinsel leads can slap against the speaker frame and momentarily short the amp to ground.  I have also seen stray strands of the speaker wire touch or almost touch ground and this causes amps to shut down at higher volume.

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I was refering to the DCR..and I mentioned +/- a few tenths because the DCR is usually around 3.7 ohms.But if it reads 4.2ohms..I would still see no harm. When using a meter to find out why the amp is going into protect mode..I look for low dc readings...like 1.3ohms as an example..well basically I see this all the time..a defect or damage in the voice coil which allows the amp to play up until a certain level..then cut off..If I didn't see this ALL the time..I wouldn't have reccomended it be tested this way. I also look for shorts..I also see amps that can play through a short at moderate volume..weather it be a wire pinched..or voice coil tinsels touching..or a speaker that is internally shorted to the frame (it plays fine when you dismount it)..well you know..the basic things you check when an amp cuts out..

But after reading this post again....I might have to agree that it could be happening due to the gains being too high..it is hard to pinpoint a problem like this without actually hearing at what level this "distortion" as described is coming in. But worth a check regardless.

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