I will almost guarantee its a bad battery...

I've been doing my own stereo work for almost 20 years now and I've had my share of bad batteries and alternators...

When the voltage gets too low the amps draw massive current to make the rated output. Remember voltage x amps = watts. If the amp is trying to put out 200 watts on 10 volts, it's going to pull 20 amps which is more than the weakened electrical system can provide, hence the amp is going in to protect...

Any auto parts store should be able to test the battery and alternator in the truck for you for free. I've been wrong plenty of times before, but that's where I'd start. Bad connections can make the voltage drop happen too, so I'd go there next.

 

He also said the battery is EIGHT YEARS OLD! I've never seen one last that long. My last battery crapped out at the 6 year point; it was still under warranty (the big yellow WalMart batteries--8 year warranty!) so I got a new one for @ $45.00.

 

thanks overdrive! ill check it out! ay nice looking truck by the waY!

 

Before you go getting a cap, check all your wires...I had that prob in my Camaro, I upgraded all my alternator wires and battery cables and checked all grounds. No more prob...

Also low rides are cool too, My other rides on air

 

Care to bet some money on that? The alternator is the highest voltage point in your system. If the amp's needs are greater than what the alternator can produce, then the system's voltage drops below that of the floating voltage of the battery. At this point both the alternator and battery are discharging. It is at the moment the system's voltage drops belows the cap's voltage that the cap will discharge. And if you were to look at hte time it takes for the cap to discharge you'd realise that it is 100% depleted in a few hunderedths of a second. After which point it becomes a further drain that the strained battery and alternator have to deal with. This results in a LOWER voltage during a long bass note than without a cap.

this has been proven in the db drag lanes, Idbl lanes, and Mecca lanes and has been proven on the meter repeatedly by many many people with their own meters - myself included - yes I own a TermLab.usb meter. No cap you get x score, add cap score drops...

Heck in my class at dB Drag I can use 2 Farads of capacitance along with my total of 2 batteries. Considering when I burp at full power on the meter my engine is off Im running on batteries alone. Capacitors only hurt the score since to get your full score you have to burp for a solid 2 to 3 seconds straight.

Since when does any sub overdrive an amp? The last time I checked, it was the amp that generates all the ac voltage and amperage NOT the sub... A transducer is just a coil of wire stuck in a magnetic gap with a diaphram attached. Nothing more.




Shoes - You arent making any sense in your post. HOW and WHAT cuts in and out. Is your voltage fluctuating or is it the output you are listening to? You need to describe your symptoms much more clearly...

However DO NOT waste your money on a cap!! Even a 50 farad jobbie that will set you back a good 400 bux and be ineffective at best. The ONLY time a cap is beneficial is for a sudden bass transient such as a kick drum AND if you have a good alternator to keep up with the system's needs.

My advice is first be more descriptive as to what is going on....

 

Shoes, your battery is definitely toast. I used to work in a shop and from my experience, unless you have an Optima gell battery, they last 5 years + or - one year. If you have a lead acid battery that is 5 years or older and it still works, it is only because you were lucky to get a good battery from the lot, and you have always kept it charged well. One bad discharge after 5 years and it's done. I'm not sure I've ever seen one last 8 years. You've definitely gotten your money's worth.

By the way I have an Optima and it seems to not put out good power with the car off. I haven't checked the voltage, but the lights are significantly more dim with the engine off. Anyone else experience this?

 

ok so let me make sense of what im saying. when i turn the volume up on my stereo deck, one of my amps goes on and off. i can tell because the sound cuts off also theres a led on the amp that lights up green when powered up and then turns red when not on. So when the sound cuts off the green led turns to red. On my other amp there doesnt seem to be a problem it works perfectly fine. This problem never existed before when i first installed the two amps, i could turn it up as loud as i wanted and all the speakers work and amps also! hope this makes sense!

 

i agree with bumpin yota in that a cap is a big waste of money

1. check wire connections. (its the cheapest check).

what kind of lag is this???? be more specific. does the music cut in a out directly??? or does it get softer and louder again?

if it cuts in a out it very well could be a connection.

if it gets softer and louder its probably the battery. when you play your bass does your deck lights get dimmer with each hit? because if it does that means you battery is getting lagged because your sub is drawing too much power.

A cap is installed in sound system so it can regulate current to a constant amount. it makes the amp run at a constant voltage. digital caps will tell you what voltage the amp is getting. it basically stabilizes the voltage so it doesn't over work the vehicles electrical system.

in that sense... like bumpin yota said its worse for sound performance. you're basically limiting power to your amp rather than letting it suck the juice out of the battery!

i also can see the theory that a sub could affect an amp... but i don't know enough to answer that question. basically what i can see happening is that the amp is not strong enough to push the sub. the amp overexerts itself trying to push a sub that is rated way over the amps power. in effect, it burns out the amp.

 

i had a 500watt sony 4 channel amp hooked to two 6.5's and two audiobahn 6x9's for forever.
my cousin gave me some 400wat sony subs, i hooked one up to the amp with the rear channel bridged, putting approx 250watt max to the sub and a week later my amp is blown up.

as for the light diw when the engine is off i have a deep cycle marine battery (idk the brand it just got thrown in the truck) and the lights dim considerably with the engine off but it does not seem to affect my sound system pushing 3000watts

 

The sub didn't kill your amp, you did.

By hooking up a bridged load to the speaker load you already had, you probably dropped the ohm's down below 1 and burned up your tired amp. Most likely it was a heat related failure.

An amp doesn't know how many or what sized speakers that it's running, it only knows resistance.

I knew a guy that wired up 96 4ohm 4" speakers to a 100 watt amp at a stereo shop once to prove a point. They presented an 8 ohm load to the amp if I recall correctly, and it played fine.

Speakers don't blow amps, incorrect wiring and heat do.

 

when the amp goes out that means theres no sound coming out of the amp!

 

That's because its a sony that had been running longer than 12 months! It runs on borrowed time once it gets past the 365 day mark! Seriously I wouldnt run ANY sony equipment if it was given to me with money to boot. The stuff is GARBAGE imo...

As others have said it is impossible for ANY transducer to blow an amp UNLESS the coil in the transducer shorts to ground, or the "installer" wires the system incorrectly and gives the amp an impedance that's too low. Thats it. Any other ampl failures are operator error 99.99% of the time. Unless you run sony, then it's a 100% chance on it being a POS. (no offense intended I just hate the company with a passion. Because when I did this for a living, I got tired of ripping out sony after sony after sony for manufacturer's defects.

So exactly what was the DCR of the rear two channels bridged?

 

Umm doood your amp itself shouldnt be making any noises....lol It should be the speakers that stop making noises. Although back in the day when I was running 3 mtx 2300x's they'd make some really wierd noises. I think it was a high pitch hum from the powersupply side of the board becuse if you tapped on the heatsink, the pitch would change. lol But aside from that and the amount of heat they generated they were TANKS for amps. I literally beat the living dog piss out of my 3 and they NEVER had any issues.

Do you have a DMM? (Digital Multi Meter) This can be a LOT of different issues and not just battery or power connections... But first do you have DMM?

 

I have 8 solid years installing and repairing aircraft radio and comm systems. I also do car audio on the side and this is what I think.

If it only happens at lower RPMs than a cap wont help you. For an audio system that size the biggest cap you would need to sustain the bass is 1 farad. 1 farad only equals one volt at one amp for one seccond. To me it sounds like you problem is lasting much longer than that.

With good cables and a good battery your battery should put out enough juice to keep your music going. How bad to your headlights dim when a good note hits?

How long is your amp running before you have this problem and are your speakers impedance matched for the amp? If you amp is on for a long time and not suffeciently cooled its thermal protection circuts will activate at the higher volumes to keep it from smoking. If your speakers are not impedance matched for the amp you will greatly increase the speed of overheating and it will turn its self off in no time flat.

My $.02

Ohh, troubleshooting idea. Connect your remote line (aka power antenna line) on your amp directly to a GOOD 12VDC source. Then, crank up the volume and see if it kills. If it doesnt than your radio is dropping the 12VDC remote line due to a poor power supply internal or external.

 

bumpin- no i dont have a DMM! yea i no my amp doesnt make noise. im gonna try to see if its the speakers. does it matter if the wires are reversed like the positive side of the amp for the speaker is going to the negative side of the speaker??

yotand- Also i have to check on the impedence and what does impedence do?? also if its the radio wouldnt do that to the sub amp also??

 

you owe it to yourself to get one, even if only a Harbour Freight DMM for 2.99. You can use it to test voltage, conitnuity, impeadance, etc. It's the most useful tool for car audio you'll ever own.

 

o yes i do have one of those lol i thought u were talking about a decible meter. ill check the voltage manana!

 

Ok good!

Turn off your system, infact dont even put the key into the ignition. I want you to put the positive probe on the B+ of the amp and the negative probe on the ground terminal of the amp and tell me what the voltage is.

Do the same thing at the battery - measure the battery's voltage. Report back here what they are.

Next set the DMM to impeadance measurement and (again with keys out of the ignition) measre the resistance of each channel at the amp. Once you've done that for both channels. touch the negative of the dmm to its positive so that you measure the DMM's resistance. Post bakc what all resistances are.

Now turn on system, but keey the system paused. Remeasure voltage at battery and at amp. Engine off.

Now do it engine on, but system paused.

Please post all results.

 

Ok, here it is in general using the garden hose explination. Water is electricity. The ammount of water pressure in the hose is the voltage. The ammount of water moving through the hose is amperage. If the nozzle is off you have high voltage but no amperage. If you have a WIDE hose and little pressure you can still move massive ammounts of water through the wide opening. This just shows that having high voltage dosnt mean you have high amperage and vice versa.

Now still using the hose example your spray nossle at the end is your resistance. The more you press the trigger the less the resistance and the more/easier water (electricity) flows.

The nossle is one resistive component in the circuit. Impedance is the resistance of all components in a circuit or portion of a circuit combined. Multiple nossles and cutoff valves = hose impedance.

Amps are designed for maximum output. They will push as hard as the load will let it. If the load has to little resistance the amp will push so much power that it overheats or some other component inside lets the smoke out due to overuse. If the load impedance is at the lowest allowable limit for the source you will get maximum efficiency. If the load is at a higher impedance you will get less efficiency (less sound) but will have a lower chance of smoking your source.

Now for the radio theory. The reason I say it MIGHT be the radio is because amps remote turn on is operated by a schmidt trigger. It may turn on with a 12VDC imput but be designed not to shutoff until that imput drops below a different voltage like 9VDC. Now the one amp that remains operational may have a wider operating range than the one that is killing. One amp could be designed to turn off at 6VDC while the other one is designed to turn off at 8VDC. So, if your radio remote turn on line drops to 7VDC that means you have one amp bumping and one amp sleeping.

Another thing is that the amp that remains operational may be hogging the power from the radio. It may have a lower imput impedance and electricity always follows the path of least resistance. So, when signals get to weak to power both efficiently the running amp may be absorbing so much of that remote line that the other amp never "feels" enough voltage to turn on. I have also heard of, but never seen, amps consuming power from the remote line to make up for power drops in a high output condition.

You should check your voltage with a DMM but I am very sure everything will be fine. You will get appx 12VDC with the vehicle off and 14VCD with the truck turned on. What you need to do is watch the circuit while it is active and a multimeter is not the tool for that. It simply isn't responsive enough. The only way to see what is happening is to probe the circuit with an O-scope. They can be hard to come by but if you know someone that does MAJOR auto repair or electronics repair they should have one.

One thing that I don't think has been mentioned is that you can have a partially blown speaker where only one of the last few wraps of the coil is shorted. This would sound fine under normal listening conditions but cause problems at higher volumes. If you have a nice amp it will detect this blown speaker at higher outputs and shutdown to protect the rest of the system.

Hope this helps and let me know how things go.

edit: Yes, speaker polarity does matter. You want the speakers to jump out of the box. If your speakers are reverse wired they will instead suck into the box. It will still noise because there is still a change in air pressure but it just aint right.

 

That was a pretty good explaination, YotaND, except for the polarity description. It's not so much that they jump/suck (to use your terminology!) as it is that ALL speakers be on the same polarity to avoid one speaker cancelling the sound of the other(s) out with an equal but opposite movement.