Engine whine / noise through stereo speakers

[keninsb]

I know this topic has been posted before, but I am looking for any new ideas that may be out there.

I installed a Kenwood HU, and two MTX amps (4 channel for the fronts and rears, and sum out to the 2nd amp that drives the sub), with Infinity Reference series speakers (6 1/2" and tweeter with crossover in front, 6"x9" Triaxles in the rear, 10" sub). After the install, I noticed that I had an engine "whine" or alternator noise over the speakers (front and rear). The noise is constant, and does not change when the volume is turned up, but does rev with the engine.

I have tried the following:
-New RCA cables (supposed to be good ones, called Tsunami).
-Re-routed RCA cables to make sure they were run seperate from power.
-Cleaned ground (to bare metal) and grounded within 18" of amp(s).
-Checked ground to HU to ensure good ground.
-Ran a ground directly from the vehicle battery to the ground on the HU and the amps, no change.
-Disconneected the front channels, still had noise in the rear and visa versa.
-Ground loop isolators (the stereo place in town let me try them, but they did not make a difference).

I was pretty anal about the install too. ALL connections were crimped AND soldered. All wires were wrapped in electical tape and run through wire loom (the black plastic fexible stuff). I am kind of at my wits end here.

The only thing I noticed that made a difference was if I put a wire from a known good ground to the ground on the RCA plugs. This seemed to help eliminate the noise.

I am wondering if I can put a permanent wire from ground to the ground (or NEG) on the RCA jacks. Does anyone know if this will harm any of the equipment? Any thoughts are GREATLY appreciated. The stereo place wants $65 per hour to isolate the problem and they said it can take 6 hours (yikes).

Thanks

Ken

[fred405]

Actually the solution is rather simple. I have been installing comercial (police etc.) radios and Ham radios for decades. You are getting alternator and /or ECM noise through the power line. The solution is to put a "Choke Filter" in line on the positive power feed. It's hard to know if it getting into the reciever or one of the amps so the best thing to do is to place one at each unit. Put the filter near the amp/reciever as some of the noise may be picked up by the wire between the battery and the device. You could get one filter and use trial and error to find the amp device that has the crappy internal filtering but you may have more than one. A good audio shop should have a filter. They either look like a transformer with a metal frame or a doughnut with wire wraped around it. Some are enclosed in a box and some have alot if fancy looking crap that they over charge for. The simple choke filter with the proper (VERY IMPORTANT) amperage rating will do the trick. Be careful, I have seen filters rated for 25 amps with 18 gage wire that is good for only 10 amps. Good luck!

Originally Posted by keninsb

I know this topic has been posted before, but I am looking for any new ideas that may be out there.

I installed a Kenwood HU, and two MTX amps (4 channel for the fronts and rears, and sum out to the 2nd amp that drives the sub), with Infinity Reference series speakers (6 1/2" and tweeter with crossover in front, 6"x9" Triaxles in the rear, 10" sub). After the install, I noticed that I had an engine "whine" or alternator noise over the speakers (front and rear). The noise is constant, and does not change when the volume is turned up, but does rev with the engine.

I have tried the following:
-New RCA cables (supposed to be good ones, called Tsunami).
-Re-routed RCA cables to make sure they were run seperate from power.
-Cleaned ground (to bare metal) and grounded within 18" of amp(s).
-Checked ground to HU to ensure good ground.
-Ran a ground directly from the vehicle battery to the ground on the HU and the amps, no change.
-Disconneected the front channels, still had noise in the rear and visa versa.
-Ground loop isolators (the stereo place in town let me try them, but they did not make a difference).

I was pretty anal about the install too. ALL connections were crimped AND soldered. All wires were wrapped in electical tape and run through wire loom (the black plastic fexible stuff). I am kind of at my wits end here.

The only thing I noticed that made a difference was if I put a wire from a known good ground to the ground on the RCA plugs. This seemed to help eliminate the noise.

I am wondering if I can put a permanent wire from ground to the ground (or NEG) on the RCA jacks. Does anyone know if this will harm any of the equipment? Any thoughts are GREATLY appreciated. The stereo place wants $65 per hour to isolate the problem and they said it can take 6 hours (yikes).

Thanks

Ken

[keninsb]

Originally Posted by fred405

Actually the solution is rather simple. I have been installing comercial (police etc.) radios and Ham radios for decades. You are getting alternator and /or ECM noise through the power line. The solution is to put a "Choke Filter" in line on the positive power feed. It's hard to know if it getting into the reciever or one of the amps so the best thing to do is to place one at each unit. Put the filter near the amp/reciever as some of the noise may be picked up by the wire between the battery and the device. You could get one filter and use trial and error to find the amp device that has the crappy internal filtering but you may have more than one. A good audio shop should have a filter. They either look like a transformer with a metal frame or a doughnut with wire wraped around it. Some are enclosed in a box and some have alot if fancy looking crap that they over charge for. The simple choke filter with the proper (VERY IMPORTANT) amperage rating will do the trick. Be careful, I have seen filters rated for 25 amps with 18 gage wire that is good for only 10 amps. Good luck!

Fred405 thanks for the quick response.
One question (and probably a stupid one so I apologize in advance):
What amperage should I look for on the choke filter? I guess it probably depends on how many amps each device is drawing. Thought you may have a good idea from experience.

Thanks again.

Ken

[nhparrot]

From your description of the problem and the symptoms, I would have to say you have a floating ground problem. Are all your grounds to chassis?

[keninsb]

Originally Posted by nhparrot

From your description of the problem and the symptoms, I would have to say you have a floating ground problem. Are all your grounds to chassis?

Hi Glenn.

The ground at the HU is through the stock setup (I purchased an aftermarket adapter that plugs directly into the wiring harness for the stock stereo). Both amps are grounded at seperate seat mounting bolts. I made sure to sand the area to bare metal.
Probably just ignorance on my part, bu I didn't think the ground was the issue because I tried using a jumper cable to ground from the vehicle battery (and other good ground locations) directly to the ground on each device (both amps and the HU) and it didn't make a difference.

Thanks,

Ken

[fred405]

A good clue is the fuse size, a device using 20 amp fuse would require a filter rated for 20 amps minium. I looks like you have grounded everything well. Usually a short lead to an uppainted hunk of body metal will do it.
Fred.

[Avionix]

Dude, what fixed this for me on an Alpine and a 300 watter amp, ground the HU to the same place you ground everything else...the screw with the amp/HU/sub, wahtever...all on the same spot, and sand a little primer/paint off. Worked for me, made me happy not to have to pull it all apart again.

-=A=-

[OKCTundra]

Ken,
I don't have a lot of knowledge in this area, but I had an engine noise problem that drove me crazy. I tried everything that you outlined and could still never take it out completely. One thing that definitely helped the problem was to turn down the gains on the amp. It didn't completely resolve the whine, but it helped. The final fix was to replace the amp that was causing the whine. I bought one from TS when they had a one day sale for a great price. When I put it in place of the problem amp, I didn't change anything else and the whine is gone.
I couldn't tell for sure, but I thought you might be using the pass thru from the front/rear amp to go to the sub amp. Every now and then you get an amp that's defective. You might try bypassing just to see. Hope this helps.
Link

[JnEsPappa]

To help deide where you put the choke, check out www.davidnavone.com for the "Muting Plug" instructions. You make a set of RCA plugs which will provide a zero noise signal input to the amp. If you connect the muting plugs to the amp input and there is still a whine, then it is coming from the amp and you know you need to put the choke in the amp's power supply wire.

[keninsb]

Thanks for all of the advice guys. This is exactly what I was hoping for. This site is GREAT!
Good tip on the fuse size relating to the filter amperage rating. That will greatly help. Thanks again Fred405.
Avionix: I tried that. I used a set of jumper cables and ran a graound from the vehicle battery directly to the HU and the amps. No change. I also tried running the jumpers from the battery to the existing ground for the HU and amps and there was still no change.

One other question: If the problem is in the amp (which has been suggested by a couple of people), will installing the filter still help? The filter isn't harmful to any equipment, is it?

Thanks again everyone.

Ken

[Agent WD-40]

Originally Posted by keninsb

One other question: If the problem is in the amp (which has been suggested by a couple of people), will installing the filter still help? The filter isn't harmful to any equipment, is it?

I'm thinking that installing a filter could help. It depends on what the problem is. High frequency electronic pulses can go down the power wire of you amp and if your amp is sensitive to them it can induce the noise into your speakers. A filter for the power line wont hurt anything. I'm assuming they are just some stort of passive filter (low pass most likely) that will keep the high high frequency pops out of the power line. It is probably just a high amperage inductor that you will stick on the power line.

[keninsb]

I went to DOW electronics today to see if they had any filters. They said it was an item that they did not stock but could order. DOW has really gone down hill. The last 5 times I have been there, they either couldn't help me (because they didn't know what they were doing) or didn't stock the item I was looking for. Weak.
Anyway, I checked out the David Navone site and will call them Monday to see what they recommend.

Thanks again,

Ken

[akauth]

You'd be surprised what it takes to resolve this stuff sometimes. It might not be as hard as you thought, but then again with those amps it might be impossible. Switching amps helps.

Sorry if I don't follow your thread completely to see what you've done but it's still pretty basic. Often you can break all the rules and everything comes out fine. Too, sometimes you follow all the rules and it still doesn't work. You have to change components - either get better or cheaper ones or at least different........

First of all you need to find out which component is noisy. Pull the RCA jacks out of the first amp and the second amp and see if you still get noise coming out the speakers. If you do, the problem is purely from power/ground and the amps.

a) Make sure that all the grounds come to a common location.
b) ISOLATE the amps bodies from metal contact. That means the you need to lift if off its mounts with spacers. The ground wire should be the only ground. NOT the amp body (sometimes reversing this solves the issue too). You can even mount on pieces of wood if you need to.
c) You can try a choke in the power lines but don't be surprised if this doesn't work. Honestly, this really shouldn't be necessary.
d) Put a capacitor on your alternator.

If you can - try to swap out ANY other amp with one of the ones you have. "Usually" a higher quality amp is much more likely to completely filter noise like this - you're getting what you pay for. But sometimes you can put in a dirt cheap amp that's fairly clean and it works better too.

Usually "more money" means better performance but like I said, you can swap a $100 RCA cable with one that is $10 and the $10 one can be noise free. I've had that happen. I've spent more money on cables (only) than most people spend on the head unit and found that $10 cables did just as well in the system.

And you can get RCA cables that have grounds on them at both ends to reduce induced noise - but I've had those be noiser than cheapo cables that I put in to solve the issue. It's worth a shot though.

As someone mentioned - turn down your gains way down (and use more powerful amps).

If the noise is coming out the RCA jacks then the head unit is noisy from it's power line or the induced noise is too strong relative to your signal (hope it's a least 4 volts).

a) Run the head unit of a separate battery you dragged into the vehicle for testing the power source. Noise - try to choke it at the power source or at the alternator with a capacitor.

b) If it's through the RCA cables - get better cables (or cheaper ones). Make sure that you're not running near power lines (you already did this).

It is okay to cross power, just don't run it along side for very long. I've broken this rule too and it was fine - each vehicle is can be unique.

If the issue is still the RCA cables you might have to get new amps that filter noise better (like alpine, for example) or get a head unit with higher voltage outs so you can turn down the gains on you amps (greater signal to noise ratio from higher voltage inputs).

As a word to the wise - if you do the above and you still get noise you'll probably have to swap amps or put up with the noise. You might find that paying the bucks to let the pros do it (they do this all the time) might be better and you'll be happier with the results in the long run. Probably changing one major component will shut down the issue. If you swap an alpine amp (not that they're the best by any means) for your front and rear speakers the problem would probably go away.

It only hurts your pocket once, but after a while you forget the pain and then you can enjoy your stereo.

(Oh, too, it might be overkill, but use spiral wound wires wherever you can). Speaker, RCA, even smaller power summed to the right sized for you watts. But don't believe that you can't get a really clean system with cheap RCA cables and 2 volt outputs because you can - in many vehicles, that is.....)

Alan

Originally Posted by keninsb

I know this topic has been posted before, but I am looking for any new ideas that may be out there.

I installed a Kenwood HU, and two MTX amps (4 channel for the fronts and rears, and sum out to the 2nd amp that drives the sub), with Infinity Reference series speakers (6 1/2" and tweeter with crossover in front, 6"x9" Triaxles in the rear, 10" sub). After the install, I noticed that I had an engine "whine" or alternator noise over the speakers (front and rear). The noise is constant, and does not change when the volume is turned up, but does rev with the engine.

I have tried the following:
-New RCA cables (supposed to be good ones, called Tsunami).
-Re-routed RCA cables to make sure they were run seperate from power.
-Cleaned ground (to bare metal) and grounded within 18" of amp(s).
-Checked ground to HU to ensure good ground.
-Ran a ground directly from the vehicle battery to the ground on the HU and the amps, no change.
-Disconneected the front channels, still had noise in the rear and visa versa.
-Ground loop isolators (the stereo place in town let me try them, but they did not make a difference).

I was pretty anal about the install too. ALL connections were crimped AND soldered. All wires were wrapped in electical tape and run through wire loom (the black plastic fexible stuff). I am kind of at my wits end here.

The only thing I noticed that made a difference was if I put a wire from a known good ground to the ground on the RCA plugs. This seemed to help eliminate the noise.

I am wondering if I can put a permanent wire from ground to the ground (or NEG) on the RCA jacks. Does anyone know if this will harm any of the equipment? Any thoughts are GREATLY appreciated. The stereo place wants $65 per hour to isolate the problem and they said it can take 6 hours (yikes).

Thanks

Ken

[keninsb]

Originally Posted by akauth

You'd be surprised what it takes to resolve this stuff sometimes. It might not be as hard as you thought, but then again with those amps it might be impossible. Switching amps helps.

Sorry if I don't follow your thread completely to see what you've done but it's still pretty basic. Often you can break all the rules and everything comes out fine. Too, sometimes you follow all the rules and it still doesn't work. You have to change components - either get better or cheaper ones or at least different........

First of all you need to find out which component is noisy. Pull the RCA jacks out of the first amp and the second amp and see if you still get noise coming out the speakers. If you do, the problem is purely from power/ground and the amps.

a) Make sure that all the grounds come to a common location.
b) ISOLATE the amps bodies from metal contact. That means the you need to lift if off its mounts with spacers. The ground wire should be the only ground. NOT the amp body (sometimes reversing this solves the issue too). You can even mount on pieces of wood if you need to.
c) You can try a choke in the power lines but don't be surprised if this doesn't work. Honestly, this really shouldn't be necessary.
d) Put a capacitor on your alternator.

If you can - try to swap out ANY other amp with one of the ones you have. "Usually" a higher quality amp is much more likely to completely filter noise like this - you're getting what you pay for. But sometimes you can put in a dirt cheap amp that's fairly clean and it works better too.

Usually "more money" means better performance but like I said, you can swap a $100 RCA cable with one that is $10 and the $10 one can be noise free. I've had that happen. I've spent more money on cables (only) than most people spend on the head unit and found that $10 cables did just as well in the system.

And you can get RCA cables that have grounds on them at both ends to reduce induced noise - but I've had those be noiser than cheapo cables that I put in to solve the issue. It's worth a shot though.

As someone mentioned - turn down your gains way down (and use more powerful amps).

If the noise is coming out the RCA jacks then the head unit is noisy from it's power line or the induced noise is too strong relative to your signal (hope it's a least 4 volts).

a) Run the head unit of a separate battery you dragged into the vehicle for testing the power source. Noise - try to choke it at the power source or at the alternator with a capacitor.

b) If it's through the RCA cables - get better cables (or cheaper ones). Make sure that you're not running near power lines (you already did this).

It is okay to cross power, just don't run it along side for very long. I've broken this rule too and it was fine - each vehicle is can be unique.

If the issue is still the RCA cables you might have to get new amps that filter noise better (like alpine, for example) or get a head unit with higher voltage outs so you can turn down the gains on you amps (greater signal to noise ratio from higher voltage inputs).

As a word to the wise - if you do the above and you still get noise you'll probably have to swap amps or put up with the noise. You might find that paying the bucks to let the pros do it (they do this all the time) might be better and you'll be happier with the results in the long run. Probably changing one major component will shut down the issue. If you swap an alpine amp (not that they're the best by any means) for your front and rear speakers the problem would probably go away.

It only hurts your pocket once, but after a while you forget the pain and then you can enjoy your stereo.

(Oh, too, it might be overkill, but use spiral wound wires wherever you can). Speaker, RCA, even smaller power summed to the right sized for you watts. But don't believe that you can't get a really clean system with cheap RCA cables and 2 volt outputs because you can - in many vehicles, that is.....)

Alan

That's a lot of info. Thanks for the suggestions Alan. The guy at the stereo place said the same thing about the amp. He said that MTX amps are good, but it may be a incompatibility issue between components.
Thanks again.

Ken

[keninsb]

OK, so I installed a filter in line (here http://www.davidnavone.com/detail.asp?PRODUCT_ID=N-25) and still have engine noise. I also double checked my ground, and shortened the cable a little bit. Not sure what else to do.
Does a ground loop problem make a whine that changes with engine speed?
I am starting to suspect the amp, but I thought that even if it were the amp the filter would take care of the noise.

Ken