What could possibly be wrong with my amp?

accidentprone86 · Dec 24, 2005

So my sub amp works intermitently. It is an audiobahn a6005dn class D.

I have it hooked up and it only works half the time. It powers on and off the way it is suposed to weather it is working or not. I have checked ALL of the leads in and out of the amp with a voltometer in both conditions.
EVERYTHING is exactly as it is supposed to be Except for the speaker out put.
No volts When not working and ranging volts when working.

What the Hell could cause this? The weirdest part is When it works and i start the car it will quit working, then when I turn the car off it will usually start working againe.
What could cause this, either inside or outside of the amp?

Camman · Dec 24, 2005

a few Things that come to mind, but I am not familiar with your amp so your going to have to help me out. Is it a regulated power supply? Its possible you are not feeding it enough when it is not working(ie alt is week). Is it possible your wire from the battery is loose and intermitently making contact? Make sure your rca cables are tight on both ends(stereo and amp). Are you running any other amps?

The other, which is not so good, would be your power supply in the amp. Usually it ends up being a bad diode or something cheap, but unless you know how to fix it... gonna cost a bit. I don't think however there is such a thing as an intermittant diode

Daggar · Dec 24, 2005

My speculation will be alternate possibility to Camman's.

My theory is that the amp is working correctly. Most have thermal protection of some sort and will shut down before the amp is damaged (sounds like what is happening in your case). You're speakers are drawing too much current. You need to take a look at the speakers are wired to your amp. If you have mutiple speakers wired to the amp in parallel then you're reducing the effective resistance of those speakers by half. Many car audio components are designed to run speakers with a 4 ohm resistance. By connecting multiple speakers to the same output in parallel you're dropping that reistance down to 2 ohms (causing the amp to shut down). I've also seen a pretty large number of sub speakers that come off the shelf that are manufactured for 2 ohm. This can be a problem as well if the amp is not specifically designed 2 ohm speakers. I've also seen speakers that advertise themselves at 4 ohm but have multiple voice coils. If those voice coils have their own separate leads and you hook them all up together then their compbined resistance is cut in half.

Solution/s:

If a multi speaker setup. Rewire them in series (this is a temp fix) --or--

Go to your favorite audio shop and purchase an inline 2 ohm resistor for each speaker you have attached to your amp.

If it's a single speaker setup then you will need just one inline resistor.

Camman · Dec 24, 2005

My apologies, I was making the assumption this was not a new install. Daggar's advice is spot on for a new install. Sorry for the confusion

Daggar · Dec 24, 2005

Camman said:
My apologies, I was making the assumption this was not a new install. Daggar's advice is spot on for a new install. Sorry for the confusion

You might be right bro. I was just posting another possibility.

PuterAmI · Dec 24, 2005

To the OP...
See my reply on FourEyedPride.

accidentprone86 · Dec 24, 2005

My set up is.
I have a 4-channel amp audiobahn a6004t 4x75 watt rms at 4 ohm. My speakers are infinity kappa series all the way around.
My sub amp is 1x300 watt rms at 2 ohms "stable at 2 ohms". My sub is a single 12 inch audiobahn 400watt rms at 2ohms "it is wired down to 2 ohms".
To give the amps signal i have a deck with three preouts.

My 4 channel amp Always works and it sounds beautiful!
My power is 11.95 volts at the distribution block and directly at both amps. This is with the ground on the voltmeter being touched to the same grounds the amps are using.
My remote turn on is giving 11.97 volts to both amps.
These numbers are when they are working AND when the sub amp is not working.
Like i said both amplifiers are ALWAYS turned on when the key and the deck are on.
The 4 channel always sends a signal to the speakers. But when the sub is not working the amp is not sending a signal to the subwoofer. I tested the input to the amp by switching the Rear RCA on the 4 channel with the Sub RCA on the mono. The sub RCA sent a clear signal to my rear speakers. The Rear RCA was plugged into the sub amp and still no sound from the woofer, yet the amplifier is powered on.

This seems to some how be related to when the car is turned on. The sub USUALLY works when the car is not running but sometimes it doesn’t even work then. My main 4g wire that powers both amps is also hooked to the proper side of the starter solenoid.
I do have a weak alternator that doesn’t charge at idle But I have a brand new battery.
My buddies even started my car revved it up at a constant 3000rpm, did the same to his car and hooked our batteries together with jumper cables. We did this thinking the sub amp was not getting enough power with the motor running to send a signal to the sub, BUT even this did not work.

I am at a total loss here the sub amp is always turned on but dose not always send a signal to the woofer.

Euphoric306 · Dec 24, 2005

i ran for a while without my gauge cluster in, my sub amp stopped working a few minutes before my battery died. this was due to the fact that the alternator does not work when the voltmeter in the guage cluster is disconnected.

i assume you still have the 65 amp alternator in your car you need to upgrade to the 3g if you're running two amplifiers (along with all the other stuff)

do you ever have trouble starting the car?

sounds as if the battery has enough juice to power the sound system when the car is not running, but then it may run out and thats why it goes off. also when you start the car, the ignition system is drawing amperage and that may cause (what i assume is the larger amperage amplifier) the sub amp to cut out.

good luck and i again urge you to upgrade to a 3g amp even if it is not the immediate problem you are facing. its easy, fairly cheap, and a lot of good insurance

1991vert · Dec 24, 2005

some amps automatically shut off it they start to overheat. i know mine do. put them in a more ventilated area? i also had another problem with music cutting in and out when i was driving. it turned out to be the wire to the battery terminal was loose and not bolted down tight. bad connection.

i can tune my amp power through my head unit. it goes from 1-16. if you have that option, try putting it down a little.

accidentprone86 · Dec 24, 2005

That is the thing, the amp does not turn off it just quits sending a signal to the woofer. So the car does still have enough power to keep it on at all times.
I do have a 160 amp 3g alt in the mail. But i dont think that is the problem considering I had my car running and my friends car runiing with a boost from his battry and it still would power on (like everyother time) But no signal is scent to the woofer.

Could something be wrong internally in the amp?

1991vert · Dec 24, 2005

then i think it's doin it's job. is the amp hot when it shuts off? you could've fried eggs on mine. mine was in the trunk of my convertible, turned up to 14/16 power underneather a retracted convertible top. barely any room to breathe. with 2 other amps back there, they werent nearly as hot and kept sending signals.

the amp would start sending a signal after it cooled down a bit. i've since relocated the amps

accidentprone86 · Dec 24, 2005

Well there is acutually penty of room for them to breath. They have internal cooling fans and the are placed under both of my 5x7s on the rear deck, they move a bunch of air. I wouldn't imagine cooling being a problem givin there placement and how cold it has been latly.

I have had a lot of mixed replys about everything oout side of the amp but Is there something inside of the amp that could cause it to intermittenly not to send a signal to the speaker while still on?

Daggar · Dec 24, 2005

It won't cost you much to wire a resistor in series with your amp and speaker. I still think that your amp is shutting down because of the current draw and that the resistance from your speaker is less than what it should be.

accidentprone86 · Dec 24, 2005

Daggar said:
It won't cost you much to wire a resistor in series with your amp and speaker. I still think that your amp is shutting down because of the current draw and that the resistance from your speaker is less than what it should be.

The amp is 2 ohm stable and the sub is rated at 2 ohms.
If you are right, would a capacitor fix the problem?

Daggar · Dec 24, 2005

No sir... a capacitor will not fix it. If it's a single speaker sub then you would need to wire 2x 1 Watt 4 ohm resistors in parallel with your speaker in order to increase circuit resistance 2 ohms (if my thinking is straight). This will make your speaker circuit a 4 ohm circuit and should relieve some of the stress on the amp. If you're able to wire up that speaker for 4 ohms then try that first.

Edit: Even though a speaker is rated at 2 ohm, that rating would be nominal. I also took notice that your speaker is 400W RMS while the AMP is 300RMS bridged. So the speaker certainly seems capable of taking everything the amp has to give and then some.

Daggar · Dec 24, 2005

I would also heed the warning of the others about ensuring that power and ground are as good as they possibly can be. The more power that amp puts to that sub, the hotter it will get. If power coming in is less than desireable, the heating of the amp will occur at a significantly higher rate.

Daggar · Dec 24, 2005

My numbers are off up there for the resistors....

Before I set out to try to find the correct numbers.... are you able to wire up your sub for 4 ohm?

Edit: In other words: Is your sub a dual voice coil?

accidentprone86 · Dec 25, 2005

yes it is a dual voice coil.
I get what you are saying about wiring it down to four ohms but i would only have half the power into the sub, right?
Also so i am not 100% sure about why you said the amp would quit sending a signal to the sub. It now wont send a singal at all weather the car is runing or not, But when the amp turns off their is a Big bump from the sub.

Edit: Would it be possible to include a wire diagram for the sub voice coils. I remember though i wired the sub diagram that was included with the amp and i still had the problems. My buddy wired it down to 2 ohms and said i was probably only get 100 watts to the sub.

Black1987Stang · Dec 25, 2005

My system did the exact same thing, it was the one the kid had when i bought my stang. It was an Infinity with a 400watt amp...it was the goofy looking kind cuz it has the amp like built into the side of the box along with the one 12 inch sub. I had 4 gauge power and ground wires, and a 1/2 farad capacitor. It would just cut in and out at random times just like ur describing. There wasnt any patterns at all:heat, weather, going over bumps etc. all i remember was that i was listening to a cd then all of a sudden I would hear BOOM BOOMM and it would work fine for the rest of the ride. Then I got a "real" system a 1200watt Power Acoustics amp and a box with 2 12's and it never skipped a beat.....until i hooked up the remote wire while the cd player was running i got some magic smoke coming from the amp and took it apart to see one of the voltage regulators got fried or it was a transistor i couldnt tell.

Daggar · Dec 25, 2005

If it's a dual voice coil speaker and is currently wired for 2 ohms then your wiring will resemble something like this:
Both voice coils are being equally fed by the amp and resistance is being cut in half. If each coil is 2 ohms then wiring it this way reduces their combined resistance to 1 ohm (not good).

What you need to do is rewire it to look like this:
Voice coils are conneted in series. Their resistances are stacked. 4 ohms total if each coil is 2 ohms.

Swapping from 2 ohms to 4 ohm will reduce max volume a little but will not cut it in half.

When voltage is reduced and amps are raised or vise versa in equal proportions, the wattage rating is still the same. If what I think is happing with your system is actaully the case then your speaker and amp will BOTH perform better. Your amp is currently feeding current as fast as it possibly can and is still not able to provide for that monster speaker you've got there. Instead, it's cutting off. What you will be doing is reducing current flow to the speaker but increasing voltage to it (by turning up the volume knob). Your amp is cutting out before your speaker is getting the necessary voltage to perform well. That at least, is what I think is going there.

What could possibly be wrong with my amp?

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