Hi,
I'll go out on a limb and say I think your alternator is fine. Since you have the noise without the car running at all, don't let the monkey's at the shop screw ya. As long as it keeps the battery charged don't give it a second thought.
Also you never said it was "whine" that increased in pitch when you step on the gas, so if that's not the case, I think you can rule out everything like the alternator, bad plugs/wires, distributor, and proximity of signal wires with power wires.
What happens when you unplug the RCA's to the amp and turn it on like that site suggested to test if the amp is fine?
Should hear nothing, and it sounded like such an easy /effective test!
If you do try the "straight to the battery" just use some long/ cheap jumper wires, fasten em down good though. Shouldn't have to take anything out this way. Again, don't worry about using any kind of decent wire for that test.. it's most temporary and just to rule out a loop or short.
How is your head unit wired up/what kind is it? You said it went away when you tested the head unit run from the Ranger, so I'd think it's likely something to do with that wiring, somewhere. I hope the only wire you've got going to the cars harness for the head unit is the 5V "remote" and all others are run direct.
Sorry if I keep suggesting basic things I know that can be maddening, but all any of us here can do is guess at what you may not have tried yet, and I really think a short or loop is what you're after. Sounds more like a ground loop though.
It sounded like you didn't have a great quality ground right from the battery to the chassis though, that would be a good start for sure, and be sure to test all your ground spots to the battery itself too, just because it's chassis shouldn't be taken for granted.
Anyway I feel your pain and best of luck, please do keep us posted, I'm sure you'll get it beat, and it will have been something simple!
I'll go out on a limb and say I think your alternator is fine. Since you have the noise without the car running at all, don't let the monkey's at the shop screw ya. As long as it keeps the battery charged don't give it a second thought.
Also you never said it was "whine" that increased in pitch when you step on the gas, so if that's not the case, I think you can rule out everything like the alternator, bad plugs/wires, distributor, and proximity of signal wires with power wires.
What happens when you unplug the RCA's to the amp and turn it on like that site suggested to test if the amp is fine?
Should hear nothing, and it sounded like such an easy /effective test!
If you do try the "straight to the battery" just use some long/ cheap jumper wires, fasten em down good though. Shouldn't have to take anything out this way. Again, don't worry about using any kind of decent wire for that test.. it's most temporary and just to rule out a loop or short.
How is your head unit wired up/what kind is it? You said it went away when you tested the head unit run from the Ranger, so I'd think it's likely something to do with that wiring, somewhere. I hope the only wire you've got going to the cars harness for the head unit is the 5V "remote" and all others are run direct.
Sorry if I keep suggesting basic things I know that can be maddening, but all any of us here can do is guess at what you may not have tried yet, and I really think a short or loop is what you're after. Sounds more like a ground loop though.
It sounded like you didn't have a great quality ground right from the battery to the chassis though, that would be a good start for sure, and be sure to test all your ground spots to the battery itself too, just because it's chassis shouldn't be taken for granted.
Anyway I feel your pain and best of luck, please do keep us posted, I'm sure you'll get it beat, and it will have been something simple!
The "R" above should be moved over a little.
Anyways, i tried the two leads that were common. So, then i tried the test again, with all three leads shorted...the amp internal ground, RCA ground, and Chassis ground. Result...quite a bit less noise than without the jumper lead to internal ground. Result, still noisy. When plugged into the Deck, noise is about the same as shorting technique. If it was just a few db quieter, it'd be tolerable, but in reality, i'd like to completely eliminate this.
I think possible a new amp is in order. At least one without this noise circuit anyways. Honestly, I've never heard many good things said about these amps. A lot of distortion issues etc. I had the lower wattage one before and it distorted very badly at lower outputs, but fine for high output.
I may even go back to the amp i had before that resulted in no Noise. I used to think twice about rockford and store brands, but upon reading some other articles, as long as you have good clean power, you can't tell the difference.
I didn't manage to get to an alternator service center/auto repair place.
I plan on doing that tommorrow. That could ultimately be my problem. Just that the AC is much too high for the amp to stop it. Besides, I have tried other amps before.
A main mystery and Point of this last test.
I don't think there could have been any ground loops in this setup. I don't understand how the noise gets in.
Someone tell me how.
Amp installed in back. I double checked grounds/power supply. Less noise with connections i have there than the ones i ran from the battery. Fine.
Then i short the rca ground to the internal amp ground. Absolutely no noise. Expected, nothin on input. Then i short the ends and touch to chassis ground exactly at the amplifier chassis ground. Noise!!! So where in this loop does noise/potential arise!
It is a complete mystery to me.
Let me know your thoughts guys.
Mark
Did much more than alot of other stuff has. However, there is still a bit of noise. I also ran the leads from the front of the car to the back.
Anyways, i tried the two leads that were common. So, then i tried the test again, with all three leads shorted...the amp internal ground, RCA ground, and Chassis ground. Result...quite a bit less noise than without the jumper lead to internal ground. Result, still noisy. When plugged into the Deck, noise is about the same as shorting technique. If it was just a few db quieter, it'd be tolerable, but in reality, i'd like to completely eliminate this.
I think possible a new amp is in order. At least one without this noise circuit anyways. Honestly, I've never heard many good things said about these amps. A lot of distortion issues etc. I had the lower wattage one before and it distorted very badly at lower outputs, but fine for high output.
I may even go back to the amp i had before that resulted in no Noise. I used to think twice about rockford and store brands, but upon reading some other articles, as long as you have good clean power, you can't tell the difference.
I didn't manage to get to an alternator service center/auto repair place.
I plan on doing that tommorrow. That could ultimately be my problem. Just that the AC is much too high for the amp to stop it. Besides, I have tried other amps before.
A main mystery and Point of this last test.
I don't think there could have been any ground loops in this setup. I don't understand how the noise gets in.
Someone tell me how.
Amp installed in back. I double checked grounds/power supply. Less noise with connections i have there than the ones i ran from the battery. Fine.
Then i short the rca ground to the internal amp ground. Absolutely no noise. Expected, nothin on input. Then i short the ends and touch to chassis ground exactly at the amplifier chassis ground. Noise!!! So where in this loop does noise/potential arise!
It is a complete mystery to me.
Let me know your thoughts guys.
Mark
Did much more than alot of other stuff has. However, there is still a bit of noise. I also ran the leads from the front of the car to the back.
That demonstrates the amplifier is defective or broken
You may try to repair it though, or get your money back if warranty hasn't exprired yet
If you have enough patience, you may open the amplifier and look for fused PCB tracks, shorted diodes or burnt/open low value resistors [typical faults]. It may be also a bad solder joint issue
To know more about what's wrong inside the amplifier you may try also connecting the internal ground to thasis ground and leaving all RCAs unplugged. No noise should result in any good working amplifier. If this produces noise then the input circuit is internally shorted to chasis ground somewhere [check thatRCA connectors are not touching the metal case and that clamping diodes, if any, are not shorted]
You may try to repair it though, or get your money back if warranty hasn't exprired yet
If you have enough patience, you may open the amplifier and look for fused PCB tracks, shorted diodes or burnt/open low value resistors [typical faults]. It may be also a bad solder joint issue
To know more about what's wrong inside the amplifier you may try also connecting the internal ground to thasis ground and leaving all RCAs unplugged. No noise should result in any good working amplifier. If this produces noise then the input circuit is internally shorted to chasis ground somewhere [check thatRCA connectors are not touching the metal case and that clamping diodes, if any, are not shorted]
That demonstrates the amplifier is defective or broken
You may try to repair it though, or get your money back if warranty hasn't exprired yet
If you have enough patience, you may open the amplifier and look for fused PCB tracks, shorted diodes or burnt/open low value resistors [typical faults]. It may be also a bad solder joint issue
To know more about what's wrong inside the amplifier you may try also connecting the internal ground to thasis ground and leaving all RCAs unplugged. No noise should result in any good working amplifier. If this produces noise then the input circuit is internally shorted to chasis ground somewhere [check thatRCA connectors are not touching the metal case and that clamping diodes, if any, are not shorted]
You may try to repair it though, or get your money back if warranty hasn't exprired yet
If you have enough patience, you may open the amplifier and look for fused PCB tracks, shorted diodes or burnt/open low value resistors [typical faults]. It may be also a bad solder joint issue
To know more about what's wrong inside the amplifier you may try also connecting the internal ground to thasis ground and leaving all RCAs unplugged. No noise should result in any good working amplifier. If this produces noise then the input circuit is internally shorted to chasis ground somewhere [check thatRCA connectors are not touching the metal case and that clamping diodes, if any, are not shorted]
Hi Eva!
Thanks for the info about the poor ground connection of standard
head units. I feel a little bit old... when remembering back my playing around with some head units 20 years ago, which had a massive ground screw connection to the frame of the car... But I feel in a modern plastic cockpit, things have changed.
Even if Mark's trouble seems to be solved more or less,
- what I am wondering in general:
Why are car audio guys using two (or even more) different ground points of the car frame for the head unit and the electronics in the trunk?!
If I understood right, then the head unit is getting ground only through a wired connector... ? Why not disconecting the ground wire there and getting the ground for the head unit from the ground point of the amp in the back? (BTW how is the shielding of the antenna connected...?!)
I cannot imagine that the frame of the car provides the same potential at every point. I mean every load in the car is simply running its ground current to any point of the frame. Alternator, ignition, servo motors....
From my understanding this must cause some small voltage drops throughout the frame of the car and with this you will always find
some noise between the frame in the front and the frame in the rear....
Of course you can try to fight these issues with differential inputs and transformers, but wouldn't it be more straight to implement a proper audio ground?
Thanks for the info about the poor ground connection of standard
head units. I feel a little bit old... when remembering back my playing around with some head units 20 years ago, which had a massive ground screw connection to the frame of the car... But I feel in a modern plastic cockpit, things have changed.
Even if Mark's trouble seems to be solved more or less,
- what I am wondering in general:
Why are car audio guys using two (or even more) different ground points of the car frame for the head unit and the electronics in the trunk?!
If I understood right, then the head unit is getting ground only through a wired connector... ? Why not disconecting the ground wire there and getting the ground for the head unit from the ground point of the amp in the back? (BTW how is the shielding of the antenna connected...?!)
I cannot imagine that the frame of the car provides the same potential at every point. I mean every load in the car is simply running its ground current to any point of the frame. Alternator, ignition, servo motors....
From my understanding this must cause some small voltage drops throughout the frame of the car and with this you will always find
some noise between the frame in the front and the frame in the rear....
Of course you can try to fight these issues with differential inputs and transformers, but wouldn't it be more straight to implement a proper audio ground?
Hi,
Well the amps need a short heavy gauge cable so that always goes in back to the frame or chassis someplace. You're then left with the choice of running a wire 10+ feet just to ground the head unit to it, that doesn't make a good ground for it. I would guess the extra inductance being a good antennae. I view the frame as a star point, a real big star point. As you say I always make sure the point or points I want to ground to has good continuity to the battery. I've never had noise once doing it this way.
Well the amps need a short heavy gauge cable so that always goes in back to the frame or chassis someplace. You're then left with the choice of running a wire 10+ feet just to ground the head unit to it, that doesn't make a good ground for it. I would guess the extra inductance being a good antennae. I view the frame as a star point, a real big star point. As you say I always make sure the point or points I want to ground to has good continuity to the battery. I've never had noise once doing it this way.
...it is clear that a 10ft+ ground wire is not nice.
You seem to fear the antenna effect of the additional ground wire more than having all the high currents of the entire car machinery running through your star point. Interesting, I would have expected it the other way round, but I never analyzed this.
I will keep your input in mind for future car projects.... if any....
Cheers
Markus
You seem to fear the antenna effect of the additional ground wire more than having all the high currents of the entire car machinery running through your star point. Interesting, I would have expected it the other way round, but I never analyzed this.
I will keep your input in mind for future car projects.... if any....
Cheers
Markus
Hi Markus,
That's just how I see things
I could be wrong of course.
I'm sure we can agree all vehicles are not the same so it might not always be the case either.
With that in mind I was wondering, it's not what "stiffening" caps are for, but they must help bypass some noise? Of course, no one ever put a stiffening cap on their head unit that I saw either.
Anyone have an opinion on that?
Cheers
That's just how I see things
I could be wrong of course.
I'm sure we can agree all vehicles are not the same so it might not always be the case either.
With that in mind I was wondering, it's not what "stiffening" caps are for, but they must help bypass some noise? Of course, no one ever put a stiffening cap on their head unit that I saw either.
Anyone have an opinion on that?
Cheers
I actually have seen stiffening caps on head units. Usually only like 100,000mfd's, but still. Or i've also see big power filters using LC circuits for 12th order noise rejection in the power line. I'm not sure that it is the power source. I still want to have my alternator diagnosed.
Only reason, is because when i jumper another car to my car, i get no noise from it's alternator. So why would that be? Possible my alternator is the craps.
Anyways, thanks for all the advice guys. If the alternator checks out okay, I'm gonna get another rockford amp. Found a cheap one on ebay, and with it's differential inputs, i'll be Laughin!
Thanks guys,
Mark
Only reason, is because when i jumper another car to my car, i get no noise from it's alternator. So why would that be? Possible my alternator is the craps.
Anyways, thanks for all the advice guys. If the alternator checks out okay, I'm gonna get another rockford amp. Found a cheap one on ebay, and with it's differential inputs, i'll be Laughin!
Thanks guys,
Mark
...the more I am thinking about typical car applications with
all the audio devices somewhere spread out in the car...
I also think differential signals with high common mode rejection also at higher frequencies (noise from ignition!) are the most comfortable solution to overcome many noise issues in cars.
all the audio devices somewhere spread out in the car...
I also think differential signals with high common mode rejection also at higher frequencies (noise from ignition!) are the most comfortable solution to overcome many noise issues in cars.
Cool. That's what i totally think too. And in fact, i ordered another rockford amp with differential inputs. I know my last one with the same circuit eliminated all engine noise and it was heaven! I got a smoking deal on one too. I got one a few years old off ebay that no one knows about.
It's the rockford 750x. rated at 93.5rms X 4 but usually does like 120. I paid $160 Shipped!
The new ones do like 120rms too but rated at 110. They go for like $260.
So i'm very happy. I'll probably sell mine now as a sub amp or check it in someones install to make sure they don't get screwed.
I'm happy and think everything's gonna work out okay. I would have loved to make a differential input box that i could keep forever that would have an awesome CMRR. I don't know exactly how I would make it, but think it would work good with a proper design.
Regards,
Mark
It's the rockford 750x. rated at 93.5rms X 4 but usually does like 120. I paid $160 Shipped!
The new ones do like 120rms too but rated at 110. They go for like $260.
So i'm very happy. I'll probably sell mine now as a sub amp or check it in someones install to make sure they don't get screwed.
I'm happy and think everything's gonna work out okay. I would have loved to make a differential input box that i could keep forever that would have an awesome CMRR. I don't know exactly how I would make it, but think it would work good with a proper design.
Regards,
Mark
Differential
Well...rockford is the only company i know of that advertises the technology and it's benefits. That's only out of the amps i've looked at and considered buying. I just looked up another known brand i know. Tru amps have "Dual differential pairs of copmlimentary input transistors".
I bet other high end amps have it as well. I'd have to look around. This rockford is the cheapest one i bet though,and they are good clean solid power.
Not sure if you've ever read the $10,000 challange, but it states, that you can pick any two amps. with all crossovers bypassed, running at the maximum of the smaller amp (with a limited thd (1% i think), you cannot tell the difference. Not just one test, but you must tell like 11 out of 12 times. The amps must not have turn on noises or anything like that, and they will be perfectly level matched. It costs $100 to enter, and no one has ever won. Closest ever was 8 or something. i'll find the link and add it. It was very interesting. I think this was for car audio only. There are a few controversies over the method (bypassed crossovers, etc)Very interesting though.
Well...rockford is the only company i know of that advertises the technology and it's benefits. That's only out of the amps i've looked at and considered buying. I just looked up another known brand i know. Tru amps have "Dual differential pairs of copmlimentary input transistors".
I bet other high end amps have it as well. I'd have to look around. This rockford is the cheapest one i bet though,and they are good clean solid power.
Not sure if you've ever read the $10,000 challange, but it states, that you can pick any two amps. with all crossovers bypassed, running at the maximum of the smaller amp (with a limited thd (1% i think), you cannot tell the difference. Not just one test, but you must tell like 11 out of 12 times. The amps must not have turn on noises or anything like that, and they will be perfectly level matched. It costs $100 to enter, and no one has ever won. Closest ever was 8 or something. i'll find the link and add it. It was very interesting. I think this was for car audio only. There are a few controversies over the method (bypassed crossovers, etc)Very interesting though.
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