amp cutting out strange

Hello to all, Hope everyone had a Happy aThanksgiving.  I am a very new member here. like 2 minutes, but I have a question or problem I guess.  I installed a system in my truck about 3 weeks ago, here is the rundown:  Eclipse CD3100 HU, MB Quart PAB5400 5-channel amp, Diamond audio components up front 2 ways in the rear, and a Pioneer Premier Shallow 8 inch sub in a sealed enclosure.  I ran 4awg power and Grounded within 1 foot of the amp to a solid GND, used 12awg speaker wire to all speakers including the sub,  Monster Cable RCAs not their best model but around middle of the line (they are good ones).  I have upgraded the BIG 3 with 4awg and left the stock wiring intact.  I put gold plated battery terminals on with set screw sockets for all the extra wires.  I am getting between 14 and 15 V at the amp with the engine running.  My stock alternator is rated at 100A.  I took the truck to Autozone and let them test the Battery and Alternator, both were good.  My problem is this:  Everything works fine untill I drive the Truck, the output is good , I have received many compliments about how well the set-up sounds, but when I drive the truck the amp goes into protection mode, my HU has a power on and off feature, when I turn the power off then back on the amp resets and will play again but only momentarily.  If I am on the freeway at speed this does not happen, more so in stop and go type driving.  My Ground is good I have tested everything with a Multi-Meter many times.  Any help would be gratly appreciated.

sound like an internal amp problem

I am hoping that it is not the amp, it is brand new.  I had my wife drive to the store this morning while I had the Multi-Meter attatched to the amp B+ and GND, it read between 14 & 15 consistently with a few drops below 14 on heavy bass notes, but it did not cut off this time.  I am completely puzzled .  This is not my first install and I have never had a problem like this.  I was told that MB Quart was good stuff, is this common for their components?  Is there a weak link in any of the components I used?  I tried to build this using the best components I could for my budget.  Thanks in advance for any input.

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Also after cutting the truck off with the meter still attached the reading was 12.5V, so the battery is good (like Autozone said), and with the meter reading between 14V & 15V with the truck running I would assume the alternator is fine. 

When the guy at Autozone tested the alternator it had a peak output of 191 amps, it is only rated at 100 amps, is that a cause for concern?

I have read here that capacitors only put an extra draw on the cars electrical system, but if I am not overstraining the electrical system would a capacitor be a good idea as a regulator?

Thanks for any help you can give.

ckeeler, thank you for your response, I am not disregarding it, just hoping it is not the amp right now.

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Did you set the gain properly?

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its a 5 channel amp? you are only running the front components and a sub? did you do something like bridge the front channels and rear channels and then run each set to just the components for more power to them or something like that? what exactly are you doing with those rear channels?

I set the Gain to audible distortion then backed off starting with the sub, at 3/4 max volume on the HU.  I am going to try and start over with the gains in a little while.

Yes it is a 5 channel amp, I am running the front components off channels 1 & 2, the rear door speakers off channels 3 & 4, and the sub off of the dedicated sub channel 5.

Thank you for the input hopefully I can get this fixed, I put alot of effort into a clean install and used the best components I could afford, now I would like to listen to it.  The thing is it is hit or miss, sometimes it cuts out sometimes it doesn't, more so in traffic or stop and go city driving.

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I just went and reset the gains on the amp, I checked the voltage at the amp as i was doing this.  It seems that the voltage is dropping significantly (below 12V) with low bass notes and that is when the amp goes into protect.  I adjusted the gains lower than before, but the amp is going into protect even faster now.  I dont want it to be the amp, but I don't know of anything else it could be. 

The battery is fine, the lights dim very little when the system is working at night, but the system is only pushing 440 watts RMS, at 14V that is much less than 40 Amps, leaving 60 amps off the alternator for the rest of the vehicle.  Should I get a capacitor?  I dont want to spend any more money if it is just going to be the amp anyway. Any ideas?  I am ready to throw it all away and go back to stock.

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try and just disconnect the sub from the sub channel and  play it like normal. see if it still goes into protect mode. if it does then continue to disconnect one channel at a time until it quits going into protect mode. then connect all the others back except for the one that you disconnected that was putting it into protect. if it doesnt go into protect after that its a problem with that speaker or the wires to it, or.....(hopefully not) that channel on the amp.

Alright , I think I will try that tomorrow, tired of messing with it today, the amp works with no load whatsoever I have broken it down to nothing but B+, GND, and remote.  Then with RCAs, then with all output speaker wires, It will work and sound great for a few minutes,  Then all of the sudden it will go into protect mode, then I can turn power off and then back on to the HU and it will work again, sometimes for 2-10 seconds, sometimes it will just play (more at highway speeds).  At first I thought it was a heat issue with the amp but it does this after just starting up in the morning.  I will try what you said tomorrow afternoon, but I think it is the amp.  Thank you for your help

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I am impatient and could not wait until tomorrow so I went ahead and tested everything this evening as far as removing components to find the cause.  The components seem to be fine nothing caused the amp to go into protect mode.  But after putting everything back together and going to town the amp goes back into protect mode.  It is either the amp or the power draw from the amp.  I replaced the factory headlights yesterday and they are a larger wattage than stock so I am sure that is not helping.  The amp is going into protect mode even faster and at lower volumes than ever.

I am thinking of doing an alternator swap, the one that came on the Frontier is rated at 100A but the one for a Nissan Quest is 125A and a direct bolt up, would 25 more Amps make a difference, or am I throwing more money away?

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Yep, unless the amp is defective it seems to be shutting down on low voltage.  Upgrade the Big 3 if you haven't already and you'll need a high-output alternator.  There is also a chance the sub or one of the speakers is shorting out... Pioneer subs used to be known for defective voice coils.  Disconnect the sub and if there's no problem, try a different sub (or go to the shop where you bought it and have it tested.)

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I did upgrade the Big 3, is upgading the stock alternator of 100A to the one off of the Quest 125A enough or do I need to go larger than that? 

I am not competing, it is only a 540 watt amp, with a set of 6" components up front, 5.25" 2-ways in the rear and an 8" sub.  I was not really expecting that much of a power draw on the system. 

I have run 2 12" subs on 1000 watt amps with seperate amps for front and rear components in the past on smaller cars, and never upgraded anything, not the Big 3, alternator, or had to use any capacitors, what is the deal with this truck?

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I think I am going to try a capacitor before I do anything else.  The amp is cutting out when I first start the truck, and then again when I accelerate from a stop or slow speeds.  I guess something on the truck is drawing voltage away from the amp when I accedlerate.  I am still confused, but I am going to find an alternator from a Nissan  Quest at a U-Pull it yard in the next week or so.  I just want to listen to my radio, very frustated.

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1.  Get the amp and your speakers/sub checked out.  Go to a reputable shop and have them check it.
2.  Get your alternator load tested at an automotive electrical shop.  While you're there get your entire electrical system checked as you may have an issue that the sound system is revealing.

The above assumes there is nothing wrong with your installation or setup, based on your replies in this thread.  That does not mean there is nothing wrong, however, so while you're doing #1 above, have them verify the install.  And don't waste your money on a cap, it's not likely to help.

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Well I went today and had the system checked out.  All of my wiring is fine, and supposedly all of my components are fine.  I was worried about the amp, but it it is not the problem.  The professional I spoke with said that all of my components were good.  He spent alot of time testing everything, even pulling off the battery to test it.  He said I did not need a capacitor, the alternator may be putting out too much power.  The voltage at the amp was between 13-14.3 no matter what I was running on the truck, lights heater, blinker whatever.

The only explanation he had was that I may be getting too much power to my amp.  This does not make sense to me.  He never saw more than 14.2 volts at the amp or less than 13.8 V.  I am thinking he may not know what he is talking about.  The system is cutting out less than before, mainly at either acceleration, or braking, it does fine at normal driving. 

The installer I spoke with thinks that maybe I am getting voltage surges at accelaration or braking, but he does not have any proof of that with a Multi-meter, someone please help me out.  I know how electricity works, and I have done plenty of installs prior to this one.  How can he determine this without some proof, and what can I do to fix it?

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If the voltage was going up high enough to shut down the amp, you would be having other problems with the vehicle.  "Too much power" is not likely the cause.  You say it only cuts out during acceleration or braking? Might be a loose connection at or inside the amp.  Is the amp moving around or it is securely mounted?  You might also have an exposed speaker or power wire that is shorting out by movement as well.  If you can, turn the system on and pick up the amp and shake it.  If it cuts out, there's your problem.  The amp may be defective.

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I am leaning towwards the amp as well, this guy that checked it out did not impress me.  I am going to check all speakers AGAIN but everything seems fine.  I asked the guy why I would not be having problems with anything else if the alternator was sending too much power, he had no explanation,  Like I said he did not impress me, but he was recomended by a friend and a complete stranger.  I went to Radio Shack Last night looking for more power cable and after I explained the situation he recomended the same guy.  I could see this if I lived in a small town but I am in San Antonio TX.  I wanted to take it to someone else immediatly but I had to watch those GATORS beat Alabama!

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The amp is mounted everything in the truck is installed correctly.  I have checked everything more than once.  It has to be something with the vehicle, I have installed stereo systems before and never had this type of problem.  Usually a multi-meter will find the problem.  This is my pesonal vehicle so I made sure everything was correct.  I am embarrassed to even have to ask but this thing is puzzling me.  I was asking about a capacitor earlier but I have never had to use them before.  I have taken this thing all the way apart, all the way back to stock, I have stripped the amp, and tested it, I really have no clue.  It is even cutting off when the stereo is on mute, which means it should be sending no power to the amp. 

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The amp is still getting power from the battery when your headunit is on mute.  It isnet getting any audio signal to amplify though.  This really seems like it is an amp problem if it is cutting out when the entire system is muted.  Try sending it back as defective, or returning it for a replacement.

sounds like a loose connection or a short caused by moving wires. also try unplugging your RCAs and see if your amp still goes into protect. it could be a busted connection inside the amp too

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