Hi all,

I recently came under possession of a new RDX A-Spec. One of the first orders of business was to install aftermarket woofers (casual eardrum requirement, really). But instantly I was met with noise coming from the subwoofers which I identified as coming from the ANC module (which I unplugged, and the sound went away)

Fast forward to today, had to take my car in for a water leak and they gave me a loaner, conveniently a brand new RDX A-Spec. Now that I’ve had my car without ANC and walked into this car, I realize I like it enough to want it but I want to find a way to have both my woofers and the ANC.

Has anyone done any work figuring out which wires are the outputs from the ANC? Perhaps it would work out to put the equivalent of a subsonic filter (or WHY) on those wires alone. (yes I realize you would lose some of the ANC functionality).

T other idea I thought of was to feed the subs directly from my phone and then split that feed to the headphone jack. I don’t really care for this idea though because I prefer to use the CarPlay functionality. (Unless there’s some way to play over USB and using the headphone jack on my phone concurrently).

Let me know your thoughts? Perhaps someone has a pin out for the ANC and with that I can do some prodding and see if I can filter out those generated frequencies, or ideally dampen them enough that theyre still functional but don’t turn my woofers into 2 12 inch engine noise machines...

Happy new year everyone!

 

What aftermarket equipment are you using and how did you wire it into your car?

 

I’ve wired in an lc2i, off of the line to the subwoofer. This feeds my amp and subsequently the aftermarket woofers.

 

Here is a great thread for you-
"new sub speaker options and general back disassembly"
I too had a strange load humming at the beginning of each drive for 10 secs or so attributed to the ANC.
So I put in a switch to turn the ANC o=n/off, along with another switch to turn back to the OEM sub whenever I want to. See the thread.

long story short, that humming noise went away... don't know if it was because of a polarity issue I thought I had with the new sub... but now, it does not happen at all, reverse polarity or not.

 

what I’m getting is not a feedback hum, it’s very obviously the ANC pumping in the reverse sound through the sub channel which I am tapped into.

are you saying that you do not get any unwanted noise when your ANC is plugged in? If so, where are you tapped into to get your subwoofer input signal?

 

Sorry for confusion... I heard the same anc feedback as you I believe.
Please read that other mentioned post. I think all your questions will be answered.

 

Ive read that entire thread; even replied to it saying thank you back in September. People are just disabling ANC which is not what I am trying to accomplish here.

You had noted in that thread that you had the pinout for the ANC, do you still have that?

 

Yeah,
There have been other posts/threads on this subject which I have responded too also.
https://acurazine.com/forums/third-g...r-pain-981862/
Looking at the schematics, I put a switch on the yellow (power) line to switch it on and off (pin 11).

 

My anc 'hum' sounded like this:
-start driving car straight
-in a few seconds i heard a 50-60 hz hum, not really loud but you can definitely hear it. It would last for a few seconds. This would repeat a few times.
-after reading alot about anc in cars, it is very difficult to control it. Best if you change your sub configuration so it does not do it. I suspect that it 'learns'. since when you install a new sub the gain is going to be higher than the OEM, the feedback sensing/response of the anc would be expected to change. It so happens that some of the frequencies that the anc manipulates is around the sub level, probably 50-60 hz.It uses the sub to produce these reverse signals, and if you mess with the sub gain, it has to discover and adjust for the added gain. That is maybe why my hum (reverb maybe) went away after a while. Another fellow RDX'er never had the hum issue, so I am providing an Electrical Engineering guess (which I am one).
Let me know how it works out.

 

I just finished my sub upgrade this past weekend and am not having this problem. I pulled the signal from outputs A9 (Sub +), A18 (Sub -), A7 (RR_Speaker -), A17 (RL_Speaker +) into my amp. No LC2i in my case because my amp has that built in. Same logic though. Could you have spliced into the wrong outputs? Also make sure you're crossover frequency is set to around 100Hz and your gain isn't set too high.

 

yes the crossover is important. I lowered mine to like 80 cuz I found the fronts were handling that 100 Hz just fine. Why did you tap the rears like that? RR- and RL+ (did you mean RR+ and RR- ) ? I would think tapping the fronts would be better, and tapping on side. The ELS system is active, so there could possibly be a difference between the front and back lower frequency. Also, you never know what its going to sound like if you grab a signal from each side...just say'in.

 

I pulled from RR- and RL+ for a mono signal. I considered the fronts but decided on the rears. Perhaps the fronts or the center channel would have been better but everything sounds fine. I played some frequency sweeps and familiar songs that make use of soundstage to ensure everything sounded balanced, and it does.

 

Gentlemen, I guess what I am getting at is that I want the full functionality of ANC without any buggy feedback. Now that I have acquired the pinout for the ANC, I can see there are 4 output wires. If I can probe these output wires and see if it’s literally a raw sound signal, I may be able to remove the affected frequencies using a filter of sorts. This way the rest of the ANC still works but there is no output at my desired subwoofer frequencies. This assumes that the audio from your device is sent to the amp and the ANC input is sent to the amp and then the amp muxes the two signals to provide your final speaker outputs. Do you see what I’m getting at? I know some people do and some people don’t have issues, right now it seems that the lc2i is somewhat of the culprit.

on another note, why are you guys pulling from any speaker other than the subwoofer for your input only to cut it off with your amps filtering? Unless I’m missing something, I’m really only interested in the sound signals meant to go to the oe subwoofer and adding anything else would just be pointless.

 

I included the second audio component in case something is lost during the audio processing to the sub. My aftermarket sub can produce a larger frequency range than the OEM sub. It probably doesn't make a different since I'm still filtering >80-100Hz but I'd rather have it installed and not need it than to need it and not have it.

As for your issue, I want to consider that the issue may not be related to the ANC. You can try disconnecting the ANC module from up by the driver's footwell behind the paneling to see if you still hear the feedback.

• Does the feedback go away when you turn down the gain? Gain that is set too high often leads to feedback (and damaged equipment). You can use a multimeter to measure the AC voltage and set your gain appropriately. I can elaborate on this if necessary.
• Can you change the polarity of your subwoofer? Usually a switch to change between 0° (in-phase) and 180° (out-of-phase). Mine needed to be set to 180°.
• Where did you ground your LC2i and amplifier? A bad ground can introduce noise. Also make sure your ground wire is the same gauge as your power wire.
• Are any of your connections loose? Loose connections can introduce noise.
• Does the feedback go away when you turn down AccuBASS?

 

Actually, not sure why you want anc anyway. I have a switch that turns it on and off, and I switch all the time, trying to figure out whether its worth keeping on. I have come to the conclusion that there is no clear reason to keep it on when the stereo is on. With stereo on, I feel it removes a bit of clarity, and it feels like it I have earmuffs on sometimes... when I flip it off it all clears up. just my observation.

 

What about when the stereo is off? Can you tell if it removes much road noise?

 

I really cannot tell the difference in noise.... I just feel my ears get stuffed after a while with the anc on. It is doing what its supposed to do, but it is complicated, too many reflective surfaces, depends on your position in the cabin, and if it is not tuned just right may introduce noise. This subject is documented on the Net if you want to research further. It is not even close to the anc in headphones, which is a very controlled environment, and even with that, some manufactures cannot get it down.
With the stereo off? very subjective. They are trying to replace the engine and road noise with fake engine noise.

 

what is your equipment?