Droning..... Is actually the SUB reverbing (Update)

[Rob97RR]

I have spent a lot of time trying to figure out how to disable the ANC. The amplified drone in yours, like mine, may be coming from the sub. It is easy to diagnose if you have someone ride in the back when you open SOT. I think I've narrowed down to a faulty ground somewhere ... but who knows where. So, I've moved on to disabling ANC. Yes, removing the mics (there are 4 in the sport bar panel above the headrests - NOT the ones by the mirror those are for handsfree) should cancel all of the ANC beside the MDS generated ANC which is run through the PCM module. Needless to say, I haven't got an easy solution yet. If you don't run a soft top (go topless) and leave the SOT open fully it isn't too much of an issue. If you crack the SOT or run a soft top and have the problem that mine does, it's nearly unbearable, particularly with the exhaust valves open. Here are the possible solutions:

1. Tune through Livernois and / or cam upgrade to prevent MDS AND unplug ANC mics.

2. Upgrade the whole audio system AND get the MDS removed. This requires a new head unit that will be compatible with cameras and off road +, new amp, and new speakers. (not cheap)

3. Remove the sub completely

4. Unplug the mics and live with just the MDS produced ANC - which is still significant.

5. Find a way to turn off ANC through a OBD programmer and security gateway. I have a message into the dealer to see if they've got the capability to turn off ANC.

6. Call it a lemon and have jeep buy it back. Not a good option for me - I've got tens of thousands of upgrades into the vehicle.

I'm sharing hoping that someone here has some other solutions, as I'd like to be able to run my softop without the subwoofer having seizures.

Thanks for the info! I'm curious, if I disabled the 4 mics in the speaker bar, will I lose any sound quality when talking to others on my cell, via hands-free?

As for other alternatives, I have seen at least a couple people now who've claimed that the ANC no longer interferes if you install an aftermarket, cat-back exhaust like the new Borla Atak and S-Type. Not sure how that's possible though if it's triggered electronically when the tops open, (which very much seems to be the case with mine.) Especially when they (at least the Borla kits anyway) still retain function of the active exhaust valves.

Any thoughts?

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[Monturbo]

Thanks for the info! I'm curious, if I disabled the 4 mics in the speaker bar, will I lose any sound quality when talking to others on my cell, via hands-free?

As for other alternatives, I have seen at least a couple people now who've claimed that the ANC no longer interferes if you install an aftermarket, cat-back exhaust like the new Borla Atak and S-Type. Not sure how that's possible though if it's triggered electronically when the tops open, (which very much seems to be the case with mine.) Especially when they (at least the Borla kits anyway) still retain function of the active exhaust valves.

Any thoughts?

I did read that the ANC improves the hands free sound quality quite a bit. I don't know first hand, but I'm inclined to think that was part of Jeep's intention with the ANC. Some turbos and 4Xes have ANC as well. So, I doubt the sole intention was to drown out the hemi.

As far as the exhaust, I'm unsure. Its hard to know if those that upgraded had excessive subwoofer feedback. Maybe that's where the faulty ground or improperly shielded wire exists. I'll definitely poke around down there and see if anything stands out.

 

[dalema]

Not a solution, but if you haven’t already, maybe post on one of the facebook jeep wrangler rubicon 392 groups and see if Scott has any ideas.

 

[Monturbo]

Not a solution, but if you haven’t already, maybe post on one of the facebook jeep wrangler rubicon 392 groups and see if Scott has any ideas.

Yeah, I’ve been in direct contact with Scott about it. He is very helpful and a great guy. Thanks though!

 

[JLUWillys]

This thread is intriguing.. so I feel like my droning only happens when it's in Auto Trans.. when I MT(Paddle) and prevent the trans from immediately drag racing to 8th.. I run soft top all the time.. had the hard top on for a week.. so I really can't remember if it happened..

Now I am wondering if this is something that can be viewed from the factory amp portion, since signal obviously needs to be relayed to the sub. Crap guys.. don't do this to me.. I have massive brain spooling issues for engineering quirks..

Like ANC would need to provide some form of frequency injection in a certain range, because it would not want to interrupt audio playing.. so it would be a consistent boost or pop in a certain Mhz range that would not follow the same graph as the music. At least that would be the way to prove there is something providing an external signal to the sub that isn't derived from the headunit processing a format like music/speech etc. I wonder if you could catch it with one of the Audio Control units with amp converters . That takes the factory amp harness and uses it straight away with the high level.

I believe those units allow graphing at least ... I don't know I am a big dummy for sure.. but I will spit ball like a mofo on this one

If it's a bad ground, it would happen more at higher loads I would think.. For instance at night in the cold with more items running that have the same ground circuit path.

 

[Monturbo]

This thread is intriguing.. so I feel like my droning only happens when it's in Auto Trans.. when I MT(Paddle) and prevent the trans from immediately drag racing to 8th.. I run soft top all the time.. had the hard top on for a week.. so I really can't remember if it happened..

Now I am wondering if this is something that can be viewed from the factory amp portion, since signal obviously needs to be relayed to the sub. Crap guys.. don't do this to me.. I have massive brain spooling issues for engineering quirks..

Like ANC would need to provide some form of frequency injection in a certain range, because it would not want to interrupt audio playing.. so it would be a consistent boost or pop in a certain Mhz range that would not follow the same graph as the music. At least that would be the way to prove there is something providing an external signal to the sub that isn't derived from the headunit processing a format like music/speech etc. I wonder if you could catch it with one of the Audio Control units with amp converters . That takes the factory amp harness and uses it straight away with the high level.

I believe those units allow graphing at least ... I don't know I am a big dummy for sure.. but I will spit ball like a mofo on this one

If it's a bad ground, it would happen more at higher loads I would think.. For instance at night in the cold with more items running that have the same ground circuit path.

Thanks for chiming in! Your knowledge base sounds like it could be helpful. My sub reverberates with the head unit off.

 

[JLUWillys]

Thanks for chiming in! Your knowledge base sounds like it could be helpful. My sub reverberates with the head unit off.

I just spit ball I am dumb as a rock..

If the sub is actually activating the voice coil and producing sound.. with the stereo off.. hmm let me think here.. so is ANC intentionally using the sub and pumping 40-80Hz to try to cancel the exhaust tone.. I mean that would essentially be real ANC ..

ANC inherently creates a reverse (negative wave , like polarity reversal )image of the sound being produced to minimize or cancel the original source from being heard. So the mics believe they are hearing these ranges maybe or it's programmed that way. then the system adjusts on the fly to inject.. Which could also lead to a pop when sound changes quickly during MDS triggers.. because the necessity for low frequency reproduction is over..

So after all that rattling on.. I came across a Jeep Excerpt from a forum post :

Excerpt

The Active Noise Cancellation System is system is designed to address the change in exhaust noise whenever the vehicle is operating in Fuel Economy Mode (ECO) or 4 cylinder mode. The system relies on four microphones embedded in the headliner to detect the exhaust drone and prompt an onboard frequency generator to create counteracting sound waves through the audio system's speakers and sub-woofer. This helps keep the vehicle quiet at highway speeds.

The Active Noise Control (ANC) module performs the creation of signals appropriate to cancel engine order related vehicle noises from the engine. It creates these signals in proportion to the Engine RPM plus any other needed input.

...The ANC module obtains the engine RPM from the vehicle Powertrain Control Module (PCM).
...The signals that the ANC module creates includes at least four simultaneous signals equivalent to sine wave frequencies in designated ratios tracking the engine RPM, to cancel engine order related noises, plus other optional signals that can enhance the cancellation effect.
...To maintain the effectiveness of the noise cancellation over the full range of vehicle operating conditions and seating locations, the ANC module has four outputs and process signals from four microphone assemblies located in the headliner.
...The ANC module supports mixing the four ANC signals into any output channel at a point after all of the signal processing required
...The ANC module operates on vehicle battery power and has its state of operation controlled by CAN-B bus messages.
...In addition to performing active noise cancellation, the ANC module supplies power to the loudspeakers.


So again , the mics being deactivated (disco'd) in the roll bar may work.. however with RPM being monitored for injection as well.. it may not..

Disconnecting the ANC module would also remove power to speakers as well .. not sure what else it would do with being regulated via Canbus

To me it sounds like the system is increasing gain too much and stays engaged inappropriately.

 

[JLUWillys]

actually maybe disconnecting the mic inputs at the ANC module is the easiest way to test.. wheres the damn diagrams .. I NED PINOUTZ

 

[firedude]

actually maybe disconnecting the mic inputs at the ANC module is the easiest way to test.. wheres the damn diagrams .. I NED PINOUTZ

Thanks for updates. I was going to dc the mics but now I am going to watch and wait.

 

[caraholic]

Just noticed this recently and it’s very annoying when your slowing down.

 

[Monturbo]

Well, I unplugged my anc mics and it made no noticeable difference. This leads me to believe it’s coming from the PCM when MDS kicks in. Next step is unplugging the sub for me and see if that stops it.

 

[JLUWillys]

Well, I unplugged my anc mics and it made no noticeable difference. This leads me to believe it’s coming from the PCM when MDS kicks in. Next step is unplugging the sub for me and see if that stops it.

yeesh.. well that stinks..

 

[rubiland]

Just noticed this recently and it’s very annoying when your slowing down.

I have the exact same thing when slowing down or letting off the gas.

Is this what they are talking about?

I’ve had performance vehicles before that also make “gurgle” sounds when slowing down. I just thought this was something Jeep engineered as part of the vehicle.

Am I to believe that’s the sub reacting to something going on in the vehicle or is this some sort of desired effect?

Interesting, I kind of like it

 

[caraholic]

It’s not the gurgling for me I like that it’s a constant deep low note that occurs when you slow down. I hear it more when off road plus is being used.

 

[rubiland]

It’s not the gurgling for me I like that it’s a constant deep low note that occurs when you slow down. I hear it more when off road plus is being used.

Completely agree, but are the other posters suggesting that it’s Bass coming from the Sub?

Can’t wait to get this thing off-road.

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