Electrical impacting Car Stereo

[33fromSD]

Hey All

With the engine running has anyone notice bad feedback (popping, static, crackling) through the speakers when playing their stereo? With the engine shut off everything sounds fine, no feedback.

I have been chasing this issue from day one of installing it.

Things I've tried to resolved the issue:
1) I have tried three different (as in different brands / types) of stereos, all three result in the exact same issue

2) I have ran power & ground back to the battery to separate the power / ground from the power & ground in the wire harness from FFR.

3) I have completely rerouted my speaker wires. Originally they ran along the trans tunnel in parallel with the rear wire harness, but I re-ran them under the car on the passenger side where there is no electrical, so the only electrical power they come into proximity with is the power connection on the back of the stereo. I have then separated the power from the speaker wires on the back of the stereo.

4) I have tried several different antennas, as well as several different antenna locations (all away from any of the wiring)

I'm at a loss, I've installed dozens of stereos in my life and have never ran into an issue like this before.

Thoughts / ideas?

Thanks in advance.

Jim

[Additional Edit]
This is a simple install by the way with power, ground, front & rear speakers and the antenna (11 connections), there is no amp, no sub woofer, etc.

[JohnK]

Diagnosing and getting rid of car stereo noise can be a real PITA. Here's a good guide that might be of help:

https://www.crutchfield.com/S-7Pf7IvjFKeF/learn/learningcenter/car/noise_suppressors_installation_guide.html

[33fromSD]

Diagnosing and getting rid of car stereo noise can be a real PITA. Here's a good guide that might be of help:

https://www.crutchfield.com/S-7Pf7IvjFKeF/learn/learningcenter/car/noise_suppressors_installation_guide.html

yes it can be. :D

jim

[narly1]

Eliminating the noise at the source is the best course of action.

The various filter gadgets available are just band-aid solutions in my opinion.

Because the problem is only present when the engine's running it's probably either alternator whine or ignition noise.

You could disconnect the alternator and just run off of the battery for a bit to eliminate the former.

Ignition noise usually means that resistor wires and sparkplugs are on the agenda.

Earl

[cob427sc]

On the 5.4 liter ford shelby engine each cylinder bank has a little black item bolted to the head which is labled in the manual as "ignition suppression". Don't know if all the coyote series engines use these or not.

[narly1]

On the 5.4 liter ford shelby engine

Good point I should probably read back as to what your engine set-up is Jim.

[FF33rod]

Not that helpful but from the description of the things you've tried I suspect it is a radiated noise problem not conducted. This can happen if you run wires ( a noisy wire in parallel with one of the stereo wires) parallel to each other over significant distances or noise that is picked up by the antenna. Also have you tried specifically grounding the chassis of the stereo (not just the negative wire)? I'd try a braid from the stereo chassis to the car chassis. Is the stereo close to a CD box by chance?

Steve

[33fromSD]

I'm running just a SBF (302), carbonated / electronic ignition

Jim

[33fromSD]

Eliminating the noise at the source is the best course of action.

The various filter gadgets available are just band-aid solutions in my opinion.

Because the problem is only present when the engine's running it's probably either alternator whine or ignition noise.

You could disconnect the alternator and just run off of the battery for a bit to eliminate the former.

Ignition noise usually means that resistor wires and sparkplugs are on the agenda.

Earl

Thanks Earl, yeah, my next approach was better plugs / wires, not sure what BP Engines uses on there crate motors

[33fromSD]

Not that helpful but from the description of the things you've tried I suspect it is a radiated noise problem not conducted. This can happen if you run wires ( a noisy wire in parallel with one of the stereo wires) parallel to each other over significant distances or noise that is picked up by the antenna. Also have you tried specifically grounding the chassis of the stereo (not just the negative wire)? I'd try a braid from the stereo chassis to the car chassis. Is the stereo close to a CD box by chance?

Steve


Thanks Steve

I need to try to ground the chassis on the stereo, the other stuff mentioned I have gone through (several times now) making sure no stereo connections (power, and or speakers) are any where near the main harness.

Jim

[narly1]

I'm running just a SBF (302), carbonated / electronic ignition

Jim

Then I'd be looking at the alternator, followed by plugs & wires...

[33fromSD]

Then I'd be looking at the alternator, followed by plugs & wires...

I'll disconnect the alternator first as a sanity test.

Just to be clear on the noise, it's not a whine, or a hiss, or a buzz, it is a very loud crackling, popping intermittent but continually type sound. Also the noise is not affected by engine speed.

Jim

[narly1]

OK, so if the noise isn't affected by engine speed that rules out the alternator or plugs/wires as the source.

So the next question I ask myself is what other noise generating components (electrical or metal on metal sources) are also active but not speed dependant when the engine is running?

Cooling fan?

Fuel pump (assuming yours is electric)?

Power to both can be temporarily interrumpted to see if they are the culprits....

[33fromSD]

OK, so if the noise isn't affected by engine speed that rules out the alternator or plugs/wires as the source.

So the next question I ask myself is what other noise generating components (electrical or metal on metal sources) are also active but not speed dependant when the engine is running?

Cooling fan?

Fuel pump (assuming yours is electric)?

Power to both can be temporarily interrumpted to see if they are the culprits....

Hey Earl

Cooling fan only runs occasionally, so I don't think that is it. I thought about the defroster / heater too, but Inever run it; fuel pump (yes, mine is electrical) I'll find out shortly, I'm in the process of moving that to the rear of the car as one of the steps to solve my vapor lock issue.

Its got to be something so simple that I'm overlooking it. I have about 50 hours into this issue alone.

I have the FFR 6-in-1 gauge cluster with GPS speedometer, could the GPS antenna be causing the issue?

Jim

[narly1]

The GPS itself is only a receiver, it shouldn't be generating any noise.

Reading back through your thread, the noise is only there when the engine is turning over (running) not just when the key is in the "run" position right?

Earl

[33fromSD]

The GPS itself is only a receiver, it shouldn't be generating any noise.

Reading back through your thread, the noise is only there when the engine is turning over (running) not just when the key is in the "run" position right?

Earl

Hi Earl

Correct, when the key is on the "Accessory" or "Run" positions (without engine running) there is no noise. The noise only exists when the engine is physically running.

Jim

[narly1]

Found this: https://www.crutchfield.ca/S-AP63rLr4d2b/learn/learningcenter/car/noise_suppressors_installation_guide.html and it's got me thinking.

Given that the body is fibreglass and thus the antenna is not properly grounded at it's base maybe that's the problem.

Questions/things to try:

Is the crackling sound still present when the audio source is CD/MP3/Bluetooth as opposed to off-the-air AM/FM/satellite radio?

Pull the antenna connector out of the radio and check again?

Ground the antenna at its base and try again?

[33fromSD]

Found this: https://www.crutchfield.ca/S-AP63rLr4d2b/learn/learningcenter/car/noise_suppressors_installation_guide.html and it's got me thinking.

Given that the body is fibreglass and thus the antenna is not properly grounded at it's base maybe that's the problem.

Questions/things to try:

Is the crackling sound still present when the audio source is CD/MP3/Bluetooth as opposed to off-the-air AM/FM/satellite radio?

Pull the antenna connector out of the radio and check again?

Ground the antenna at its base and try again?

Hi Earl

I have not tried just an audio source yet, will try that.

On the antenna, I did test that, I get popping / crackling with or without the antenna plugged in, plugged in is worse than not plugged in.

I will try grounding the antenna base too.

Thanks for the ideas

Jim

[33fromSD]

Update on this issue. Still scratching my head.

* I tried audio through a Bluetooth device; still experiencing the crackling / popping through the speakers
* I tried grounding the antenna base; still experiencing the crackling / popping through the speakers
* I tried a different antenna; still experiencing the crackling / popping through the speakers
* I added an extra ground to the stereo chassis; still experiencing the crackling / popping through the speakers
* even though it's not a "whine", I didn't disconnect the alternator to rule it out; still experiencing the crackling / popping through the speakers

Tried the above on both the stereos I have.

So, besides the above to recap, I also have power and ground coming directly from the battery, completely isolated from the main wiring harness. The speaker wires are totally isolated from any other power wires in the car.

Not sure what is going on, but the issue persist with power & ground directly from the battery or the car's wiring harness, one is not better than the other.

Hard to believe that it's anything to do with the hardware, unlikely that two different model stereos, and two different types of antennas would be the issue, has to be something in the car.

Very odd.

Jim

[narly1]

OK time to go to war. We need to figure how the noise is getting into the stereo system in order to narrow down where it's coming from.

Independently power the stereo with a second battery. Anything metal in the sound system that's mounted to a metal part of the car needs to be separated from that. This incudes the chassis of the stereo deck itself, the speakers, and the antenna.

With the car off and playing music off of a CD or MP3 stick is it clean?

Start car. Is it still clean? If not it's some kind of radiated noise (EMI or RFI). Sometimes 2 pieces of metal moving against each other can generate noise. That's why you often see a ground strap between the hood and firewall on cars. Heck it could even be two exhaust pipe pieces rubbing against each other....

Suffice to say that if the noise is still present at this stage it might be very tricky to isolate the source causing it.

If it is clean then we can systematically start connecting parts of the stereo system back up to the car chassis, checking for noise as we go along. I would go in the order of antenna, speakers, deck chassis, negative wiring, positive wiring (finally doing away with the second battery at this step).

[33fromSD]

Good thought on the 2nd battery, I'll give that a try this weekend.

Jim

[PhilO]

For years I always needed to put an rf filter on the power line into the stereo. Oem car electronics have improved their design to eliminate this but these cars are not modern oem design. I would buy an rf noise filter and see if it fixes the problem
https://www.amazon.com/Mr-Ho-Amplifier-Suppressor-Isolator/dp/B0796R7LX7/ref=sr_1_15?_encoding=UTF8&c=ts&dchild=1&keywords=Car+Amplifier+Noise+Filters&qid=1627065807&s=electronics&sr=1-15&ts_id=10981591

[Nigel Allen]

G'day Jim,

I can see that you have already checked and eliminated a lot of potential issues. However, I wonder if any of the speaker wiring could be intermittently shorting to ground causing the crackling issue? Disconnect the speaker wires from the stereo and with your multimeter set to ohms, measure between any speaker wire and the chassis of the vehicle. it should show as open circuit. then perhaps try with the engine running to introduce vibration into the vehicle and see if you get any intermittent shorts to chassis then. it could be that one of the wires has rubbed through or that the terminals on the rear of the speakers are touching something that is grounded. I have even had a faulty speaker where the flexible braid that goes to the cone has touched the frame of the speaker. In this case, as the speaker cone moved in and out, the braid would rub on the metal frame, resulting in distorted audio across both the left and right speakers.

I'm sure you've probably already tried this - A second thought is that the radio is installed without an earth to the frame of the radio. run a wire from battery negative to the metal frame of the radio.

Best of luck,

Nigel

[JimLev]

Did you connect both speaker negative output wires at the stereo together so you’d only have to run one negative wire to both speakers?

[Nigel Allen]

Something else to try:
Get a battery operated portable radio and try listening to it and see if you get interference on it as well. if you do get the same noise, then you know it is RF from the vehicle. You may even be able to use the portable radio and move around the vehicle to try and locate where the RF is being generated.

Cheers,

Nigel

[33fromSD]

Something else to try:
Get a battery operated portable radio and try listening to it and see if you get interference on it as well. if you do get the same noise, then you know it is RF from the vehicle. You may even be able to use the portable radio and move around the vehicle to try and locate where the RF is being generated.

Cheers,

Nigel

Great idea, Thanks for the tip

Jim

[33fromSD]

G'day Jim,

I can see that you have already checked and eliminated a lot of potential issues. However, I wonder if any of the speaker wiring could be intermittently shorting to ground causing the crackling issue? Disconnect the speaker wires from the stereo and with your multimeter set to ohms, measure between any speaker wire and the chassis of the vehicle. it should show as open circuit. then perhaps try with the engine running to introduce vibration into the vehicle and see if you get any intermittent shorts to chassis then. it could be that one of the wires has rubbed through or that the terminals on the rear of the speakers are touching something that is grounded. I have even had a faulty speaker where the flexible braid that goes to the cone has touched the frame of the speaker. In this case, as the speaker cone moved in and out, the braid would rub on the metal frame, resulting in distorted audio across both the left and right speakers.

I'm sure you've probably already tried this - A second thought is that the radio is installed without an earth to the frame of the radio. run a wire from battery negative to the metal frame of the radio.

Best of luck,

Nigel

Thanks Nigel, unfortunately I have already tried both of these. I even went as far as running a completely new set of speaker wires from the radio to the speakers in an area of the car where there is no wiring from the harness.

Jim

[33fromSD]

Did you connect both speaker negative output wires at the stereo together so you’d only have to run one negative wire to both speakers?


Hi Jim

I actually have a 4 speaker system, and I connected each with the (+) & (-) individual leads. I was told by a local stereo shop years ago that connecting all the negative outputs together at the stereo was a bad idea.

I don't think it would matter anyway because the other day I disconnected all speakers from the stereo outputs accept one and tried running the car moving the one set of speaker wires to FR, FL, RR, & Rl outputs on the stereo and each one individually had the popping / crackling.

Jim

[JimLev]

Have you powered down the 6 in 1 gauge cluster to eliminate it as a source of interference?
Maybe the brushes in your electric fuel pump are arcing to the commutator?

[33fromSD]

Have you powered down the 6 in 1 gauge cluster to eliminate it as a source of interference?
Maybe the brushes in your electric fuel pump are arcing to the commutator?

Hi Jim

I have not powered down the gauges, I can try that.

On the fuel pump, I thought that too as a possibility when I had it in the engine bay, but I recent moved it under the fuel tank (to eliminate my vapor lock issue) so it's no longer in proximity of the main wiring harness or stereo.

Jim

[JimLev]

The fuel pump is still connected to the same power as the stereo.
If your static and popping is continuous try shutting the fuel pump power off, the engine should still run for 3-4 seconds.

[33fromSD]

The fuel pump is still connected to the same power as the stereo.
If your static and popping is continuous try shutting the fuel pump power off, the engine should still run for 3-4 seconds.

Stereo power & ground are now connected directly to the battery, I'm not using the 12V power or ground through the harness, I rewired that a couple weeks back.

But yes, you are right, anything is possible and it could the fuel pump and I will try pulling the fuse when it's running to see if the static & popping continues.

Jim

[Andrew Davis]

Jim,
I have a small "transistor" radio for when my power goes out. I found if the xfinity remote is bumped, it generates RFi on my little radio. Also the led lights in my shop interfere with my stereo, at least in the A.M. broadcast realm. If it occurs while playing a CD, it's probably on the power supply side and not RFI.
Andy

[narly1]

That's what I was trying to get at earlier. The best approach to troubleshooting a noise issue like this is to first figure out how it's getting into the sound system.
Then go looking for the source based on that.

[33fromSD]

Jim,
I have a small "transistor" radio for when my power goes out. I found if the xfinity remote is bumped, it generates RFi on my little radio. Also the led lights in my shop interfere with my stereo, at least in the A.M. broadcast realm. If it occurs while playing a CD, it's probably on the power supply side and not RFI.
Andy

I was thinking LED lights might be affecting it too since I have a ton in my garage, but when I was running the 33 outside yesterday verifying a fix for vapor lock I tried the stereo again and still popping / crackling outside the garage (car was at least 50 feet away from the LED lights).

I'm thinking it's on the power supply side. I don't have CD in the stereo but I did try playing radio through my phone via bluetooth as well and I tried using my iPod via bluetooth and direct connect through the AUX connect. All still resulted in popping / crackling when the engine is running.

Everything (AM/FM through the stereo, radio over blue tooth, iPod) are all crystal clear with no issues when the engine is not running.

I still need to try narly1's suggestion about hooking the stereo power / ground up to a 2nd battery separate from the car's power.

Jim

[33fromSD]

That's what I was trying to get at earlier. The best approach to troubleshooting a noise issue like this is to first figure out how it's getting into the sound system.
Then go looking for the source based on that.


Agree Earl, but this is turning into an elusive issue. I'm left scratching my head. There are a few things to try yet (your suggestion on battery, disconnect gauge cluster from JimLev, and some other suggestions in this string) but I'm running out of ideas.

It would be one thing if I had all the fancy gadgets others have on their 33s (door poppers, remote starts, larger stereo systems, EFI, etc., etc.), but I have a very simple system running a 302 with carb, the only things electrical are the lights (headlights, tail lights, back up lights), GPS 6-n-1 gauge cluster, clock, electronic ignition on disti, heater/defroster and this stereo. Very minimal compared to most

JimLev - I did pull the fuse on the fuel pump when the car was running to see if the fuel pump was causing the issue, car ran for about 5 seconds after I pulled the fuse but I still had popping / crackling in the speakers, so that rules out the fuel pump.



Jim

[narly1]

I was thinking LED lights might be affecting it too since I have a ton in my garage, but when I was running the 33 outside yesterday verifying a fix for vapor lock I tried the stereo again and still popping / crackling outside the garage (car was at least 50 feet away from the LED lights).

I'm thinking it's on the power supply side. I don't have CD in the stereo but I did try playing radio through my phone via bluetooth as well and I tried using my iPod via bluetooth and direct connect through the AUX connect. All still resulted in popping / crackling when the engine is running.

Everything (AM/FM through the stereo, radio over blue tooth, iPod) are all crystal clear with no issues when the engine is not running.

I still need to try narly1's suggestion about hooking the stereo power / ground up to a 2nd battery separate from the car's power.

Jim

OK, because the noise is still present even when you try a "not off the air" ie not radio (iPod into AUX input) source this means the noise is getting into the radio through an electrical connection and not being picked up by the radio receiver "off the air".

So it's either sneaking in via the antenna ground, radio chassis ground or the power leads. Eliminate each of these 3 suspected paths one at a time...

[33fromSD]

OK, because the noise is still present even when you try a "not off the air" ie not radio (iPod into AUX input) source this means the noise is getting into the radio through an electrical connection and not being picked up by the radio receiver "off the air".

So it's either sneaking in via the antenna ground, radio chassis ground or the power leads. Eliminate each of these 3 suspected paths one at a time...

Agree

Jim

[33fromSD]

Just got off the phone with the engine builder to verify the spark plug wires.

Plug wires are Moroso. They are shielded, and have RFI suppression. They use these same wires on their EFI engines ( which they say are very susceptible to interference) and they do not have interference issues with them. They have never heard of their spark plugs, or ignition components causing radio noise

Jim

[33fromSD]

Not being an electrical engineer I'm not sure if this next theory holds water, but I have done enough wiring to know that high voltage lines (coil) wreak havoc with other items.

My theory is this...the coil wire (& electric choke wire in the same bundle) runs parallel for about 16" along the aluminum firewall inside the car before exiting out into the engine bay. I'm wondering if the noise from the high voltage coil wire is turning the whole aluminum firewall into a radiation point? Thoughts?

The firewall is grounded technically because the rivets go through the frame (in dozens of spots) and the frame is grounded to the battery so I should be covered but I'm not sure.

Typically when I do grounding on restorations on any "steel" vehicle I make sure I ground three things, 1) Battery to frame, 2) frame to engine & 3) body to frame. Since there is no steel body on the 33, I did't do the last grounding (body to frame).

Jim

[33fromSD]

I tried everything suggested above with no luck, still crackling / popping / static with the engine running in both AM/FM & Aux components.

After rewiring, if you recall I had a separate ground from the stereo ground to the (-) on the battery, I ran the power to the (+) on the battery so power was totally isolated from the car's wiring harness, I also reran the speaker wires totally separate from the wiring harness (originally I had them coming up the center in parallel to the rear harnesses). I then added a separate ground wire from the stereo chassis to the frame as suggested above and, I also added a separate ground wire from the antenna to the frame as suggested above. So visualize three separate wires for ground, the issue of static, popping & crackling still occurred after all that.

Today, considering nothing else has worked I decided to combine the stereo chassis ground and antenna ground into a single connection to the frame (see pic) as a "what the hell do I have to lose" attempt, and to my shock and utter surprise, IT WORKED!! With the engine running, all the static, popping and crackling is now gone, the radio, and aux components are crystal clear with the engine running.

A ground is a ground is a ground, so can someone who is either an audio expert, or an electrical expert explain to me why combining grounds on the stereo chassis and antenna to a single grounding point on the chassis resolved the issues verses individual separate grounds?

Don't get me, I am more than thrilled that this is resolved and I can now play my stereo after chassing it for several weeks, but I cannot wrap my head around why combining grounds worked verses separate grounds.

151493

Jim

[jts359]

Back in the day Studebaker Avanti's and Corvette's had ignition shielding around the distributor and spark plug wires , I would think 50 years later that technology would have advanced so one would not have go to such extremes , But maybe not ! Ed

[JimLev]

Most likely you had a ground loop so grounding both the stereo chassis and antenna at the same point eliminated the ground loop.
Looks like I have the same antenna as you.

[33fromSD]

Most likely you had a ground loop so grounding both the stereo chassis and antenna at the same point eliminated the ground loop.
Looks like I have the same antenna as you.

Seems odd to be a ground loop when the stereo chassis and antenna while the ground wires were indeed separate, were tied to the same part of the frame under the dash within 2" of each other. Hard to believe a 2" space on the same frame section created a ground loop?

Jim

[narly1]

Car antenna cables are coaxial, meaning that an insulated center conductor runs insulated (by what we call the dielectric) inside a"tube" (made of braided wire) which we call the shield. Thus the antenna cable should be automatically be grounded when you plug it into the radio chassis. I'm surprised that they also give you a second ground at the plug end. Maybe it's not electrically connected to the connector shell? A simple ohmmeter check would confirm...

[33fromSD]

Car antenna cables are coaxial, meaning that an insulated center conductor runs insulated (by what we call the dielectric) inside a"tube" (made of braided wire) which we call the shield. Thus the antenna cable should be automatically be grounded when you plug it into the radio chassis. I'm surprised that they also give you a second ground at the plug end. Maybe it's not electrically connected to the connector shell? A simple ohmmeter check would confirm...

Hi Early

I actually added the ground wire to the shield that was bent over the outer insulation. Just plugging in the antenna to the stereo chassis mating connector without the ground still resulted in popping, static / crackling.

Jim

[narly1]

LOL "Early" only my wife calls me that, LOL.

Most of the coaxial cable used for car antennas is pretty marginal in terms of the percentage of braid coverage around the inner conductor. I'm still going to stand by my hypothesis though that either the braid is either poorly bonded to the plug shell, the jack shell in the radio itself is not grounded, or maybe even both.

The bottom line is that you figured it it out so good work.

Persistance wears down resistance.

[33fromSD]

[QUOTE] LOL "Early" only my wife calls me that, LOL.

Most of the coaxial cable used for car antennas is pretty marginal in terms of the percentage of braid coverage around the inner conductor. I'm still going to stand by my hypothesis though that either the braid is either poorly bonded to the plug shell, the jack shell in the radio itself is not grounded, or maybe even both.

The bottom line is that you figured it it out so good work.

Persistance wears down resistance. [QUOTE]

Typo ...sorry!! :(

Jim

[narly1]

It's all good Jim, you made me laugh.

[KGTM]

Do you have power amp or direct from dash player speaker output?

[33fromSD]

Do you have power amp or direct from dash player speaker output?

Direct from stereo in dash's speaker outputs to speaker wires, no power amp.

Jim

[KGTM]

Generally you do not want your antenna grounded to chassis since the coax has its own ground wire back to radio.

Now as why noise, most of the time these grounds are isolated as how is connected on the PCB, and connecting them far from each other will inject the noise difference between the two to internal ground.

At least solved.:)

Mostafa

[33fromSD]

Generally you do not want your antenna grounded to chassis since the coax has its own ground wire back to radio.

Now as why noise, most of the time these grounds are isolated as how is connected on the PCB, and connecting them far from each other will inject the noise difference between the two to internal ground.

At least solved.:)

Mostafa

Hey Mostafa

Agree on everything, which is why I was baffled by the resolution, it broke all the rules I knew for car audio.

But, like you noted it's resolved so I'm good.

Jim

[progmgr1]

I was a mechanical engineer who worked in various military and aerospace electronics companies for 40+ years (inertial navigation systems, satellite robotics, RF antenna systems, Li-Ion battery systems, etc.) Electro-Magnetic Interference / Control was a black art that caused us a lot of heartburn / labor / $, but the starting point was "always" to have a single point ground. Everything after that was just magic mixed with trial and error. Glad you found a solution relatively quickly.
Keith HR #894