20 replies to this topic

[tamastar]

Hi guys, here's the thing...

 

I've got an amp connected to a pair of front splits and a sub. When the car is on 'ACC' and engine is off, everything works fine, I can play it on high volume etc.

As soon as I turn the engine on, if the volume is anything above approx. 1/3 volume the amp will go into protect mode.

 

My guess (with not a lot of electrical knowledge) is that the battery can't supply enough power for everything when the engine is running? I just thought I'd put it up here for other suggestions before I go fork out for a battery.

 

Thanks heaps!

[allpaw4]

Check all connections. The vibration of the engine running may be allowing a loose strand to touch occasionally. Doesnt sound good though. It could be the amp is on its way out too, and the extra power its delivering due to the higher voltage (~12.5V engine off versus ~13.8V with the engine running) is tripping it into protection. There are multiple possible reasons.

[tamastar]

Check all connections. The vibration of the engine running may be allowing a loose strand to touch occasionally. Doesnt sound good though. It could be the amp is on its way out too, and the extra power its delivering due to the higher voltage (~12.5V engine off versus ~13.8V with the engine running) is tripping it into protection. There are multiple possible reasons.

I've checked all connections, everything's good. The amp is only 3 months old and a decent rockford fosgate, what else could I check?

[Hypnotic]

Check the amp settings as well, make sure the gains aren't up too high.

[Tim.]

Can you give us some more information? Like model numbers, how it's connected up and maybe a pic of the install. It'll just make it easier to troubleshoot and might be something simple/obvious from a photo.

[tamastar]

Check the amp settings as well, make sure the gains aren't up too high.

Gains are just over halfway.
 

 

 

Can you give us some more information? Like model numbers, how it's connected up and maybe a pic of the install. It'll just make it easier to troubleshoot and might be something simple/obvious from a photo.

Head Unit: Pioneer DEH-8450BT

Front Speakers: Polk Audio db6501 splits

Rear Speakers: Pioneer components

Amp: Rockford Fostage P400-4

Sub: Pioneer TS-SWX251

 

Front speakers run off the front two channels of the amp, and rear channels are bridged to power the sub. The rear speakers are powered from the head unit. Amp is installed under driver's seat and grounded under a seat bolt. I've checked all of the speaker connections for shorts and the wiring harness which is all still solid. The headlights also dim with bass hits, I'm guessing that's related. I can put some pictures up tomorrow but I don't think it'll be that simple - this stereo install has worked for months and only started doing this about a week ago.

Thanks

[Hypnotic]

Without seeing the install however just looking at what you have 2 things come to mind.

 

1) Get a bigger battery, if you headlights dim then not enough power is going to the amps (could also be the alternator)

 

2) Drop the gains down, the head unit in question has hi-volt pre-outs, so the amps could be overloading and they will clip/cut out

[Tim.]

How is you battery Negative to Chassis Earth looking? Is it making a good connection? any resistance or corrosion visible?

Any of the power cables getting hot?

Sometimes it's the simple things.

[tamastar]

Hey guys, sorry about the massive delay between last post... but if anyone still cares here's the updates haha

 

Since last time, I've bought a new Century battery, biggest I could get to fit, put new battery terminals on as well. I checked Negative to Chassis Earth it looks fine. I also moved the Earth for the amp to a different position where it gets more surface contact and is cleaner. I don't really want to drop the gains otherwise I'll lose the volume I used to have  . Nothing seems to be getting hot either. Could it be the alternator?

 

Cheers

[alexGT]

have you done a resistance check of your amp's ground to car ground?

[tmh983]

measure the voltage at the power terminals of the amp with a multimeter with the car off, then again with the car running.  Sounds to me like either a shonky earth connection, or your amp is fried...  Also check the voltage drop accross the main fuse, i've had a bad fuse that didn't look blown before, but had a high resistance and it caused some interesting problems.

[Sic'Em]

How your car audio system works is dependent on exactly how it has been wired up.

 

What power source is powering your amp?

What 'ACC' wire are you using to turn on the amp?

How exactly is the head unit connected to the speakers and amp?

 

We could be more helpful if you can provide some photos of your installation.

 

Just going by what you have explained briefly, it is wired incorrectly. It seems you are sourcing your power from a bridged/low end gauge wire which may run fine whilst there is little to no current draw on the vehicles electrical system (ECU/Lights/Etc), as soon as you 'run' the vehicle, the current draw on that circuit is in full use and unstable as the vehicles electrical system is using most of it, the voltage fluctuates and causes the amp to trip out (protect mode).

 

For a power amplifier to run proper and not overload circuits, it will require its own independent power source... that being an 8 gauge (or 4 gauge) ~60amp fused power connection run directly from the battery terminal to your amplifier, as well as the the same gauge earth/chassis connection. The blue 'remote' wire will run from the back of your head unit directly to the amplifier, so when the head unit turns on, it also powers up your amplifier. You can even go as far as also adapting in a capacitor should your voltages fluctuate still... this will keep the audio system sounding great via the constant stable voltage provided.

[tamastar]

have you done a resistance check of your amp's ground to car ground?

Not sure what you mean? Could you tell me how to do that?

 

 

measure the voltage at the power terminals of the amp with a multimeter with the car off, then again with the car running.  Sounds to me like either a shonky earth connection, or your amp is fried...  Also check the voltage drop accross the main fuse, i've had a bad fuse that didn't look blown before, but had a high resistance and it caused some interesting problems.

Cheers, I'll check that.

 

For a power amplifier to run proper and not overload circuits, it will require its own independent power source... that being an 8 gauge (or 4 gauge) ~60amp fused power connection run directly from the battery terminal to your amplifier, as well as the the same gauge earth/chassis connection. The blue 'remote' wire will run from the back of your head unit directly to the amplifier, so when the head unit turns on, it also powers up your amplifier. You can even go as far as also adapting in a capacitor should your voltages fluctuate still... this will keep the audio system sounding great via the constant stable voltage provided.

That is exactly how it's wired up, minus the capacitor.

[alexGT]

multimeter on ohms - one lead on the ground terminal on the amp, the other lead on car ground and check what it reads, should be very low (0.1 ohms)

[tamastar]

 

Some photos of the install. Obviously RCA's from the amp go to the pre-amp outputs on the back of the head unit and remote wire goes to head unit wiring loom. The ground cable from amp is bolted into stripped back bare metal behind the seat belt bolt under the side trim.

 

I just went to check voltages but my multimeter has decided it doesn't want to display a reading for anything so that will have to wait until another day.

[Sic'Em]

In that case, it's probably a faulty amp.

 

Is the amp over heating when the sound system is cranked up? You might have a bad/dry solder joint on the circuitry somewhere... tbh it could be anything. I'ts hard to diagnose with a keyboard over a forum. Take it to a car audio specialist and go through the motions of what is happening, they will soon tell you what the issue is.

[allpaw4]

Any luck with this? Just curious.

[tamastar]

For those who are interested, this actually turned out to be a faulty subwoofer which was shorting and thus putting the amp into protect mode. The sub was literally the only thing I didn't check!

[tamastar]

Any luck with this? Just curious.

[allpaw4]

That'll do it. Remember to match up your RMS wattages - too much on the sub compared to the amp will result in the sub being under powered, and not performing as it should, and too much on the amp compared with the sub will result in sub being over powered and risking frying the coils, as it seems has happened. Plus, looking at those photos, might be worth upgrading the sub wiring between the amp and sub - that stuff looks rediculously small (the sub will pull anything up to about 15 to 16 amps on that amplifier, which that cable is likely rated at about 5 amps)