Gabe15

iTrader: (1)

So Im 35 and since my first car Ive always upgraded the stereo. I recently put a 12 inch sub in my 05 RL. I left the stock system in there and had the local shop run a line converter from the stock sub to the amp for a signal then to the new sub. Problem is every time I start the car I get massive bass at low idle even when the radio is off. It goes away as soon as I give it gas or it goes away when I open a door. Im figuring its gotta do with the noise cancellation system. I now it uses the stock sub to cancel low frequencies and is the likely culprit since it is on even when the radio is off. I know you can turn Noise Cancellation off but it turns back on when you restart the car. Anyone else try to add subs to their RL?

getakey

wondering if it is related to a signal delay from stock sub thru new amp to new sub. If you are getting signal from old sub, then low frequency cancellation will also be fed to new sub, but slightly delayed due to new amp
That said, I'm not an expert (or for that matter even an amatuer) in this subject

abusive

Although I'm a new owner, I've done a lot of research about this car and I'm inclined to agree with getakey.

There was a thread discussing the ANC and someone, supposedly "in the know", stated that the frequencies used by ANC are static. I think the low value was around 300Hz.

Depending on the the amplitude of the "hum" you're getting you could try the passive approach and use an in-line inductor (coil) to subdue the "hum".

andysdesign3

im not sure but i think cause our speakers have internal amps built in them thats y its doing that...

kgd

You could try turning off the ANC.

fredren

the problem is the ANC system and i did add 2 8'' l7's couple months ago and i had the same exact problem. you have to remove the rear dome light and you will see the rear mic that is positioned right before it in the ceiling and you have to disconnect it. all you have to do is disconnect 1 clip but mine you it's kinda difficult to get to but it can be done.

Gabe15

iTrader: (1)

Whaaa Hoooo! You are right it is not easy getting to that little green connector clip but once I got it off presto! No more unwanted bass. fredren, thank you so much, the shop I had this done at had no idea what was causing it and admitted they were having a similar problem with a cadillac they had in there. You have definitely saved me time, money, and frustration.

Thanks again

Gabe

CFoote

Hi Gabe, I'm curious, have you noticed any different in noise while driving with the ANC system disabled? Just curious....I know that driving around with the stereo off is probably something that doesn't happen often

Chris

TampaRLX-SH

The ANC of the 05-08 RL primarily focuses on low frequency sounds typically caused by engine boom. You may be able to hear it by covering the microphone on the overhead console. It will not be a complete test, as the rear microphone is still working even while you cover the front microphone. This system works even when the stereo system is off. And likely this created the bass humm the OP reported.

It have tested the ANC effect best on a smooth road where there is little tire noise. Unfortunately, the OEM Michelins are noisy on coarse roads, and a create a higher frequency sound, which is not addressed by the ANC. But on a smooth road, where the tires are quiet, you may head the low pitch boom by covering and uncovering the ANC microphone.

If you really want a more effective test, cover the rear cabin microphone with some thick tape, then drive on a smooth road and cover the front microphone with you finger. The boom is more pronounced.

The 09 RL has a new iteration of ANC that is supposed to cancel a wider frequency range and perhaps, better addresses the tire noise. The new ANC version along with additional sound insulation is supposed to make the 09 RL even quieter.

But this system, if subtle is elegantly interfaced with the Bose system. Changing the architecture of the sound system will have some impact, pro or con on the stereo performance and / or ANC.

Gabe15

iTrader: (1)

Ive been paying close attention to interior noise level since I unplugged the rear mic a couple days ago. It could be that my untrained ears just arent catching the difference between rear mic on versus off because I cant tell any difference at all. If I were given a blind hearing test, one RL with rear mic attached and one RL with rear mic unattached I dont think I'd be able to tell.

Ive driven about 100 miles since then over varying road surfaces with radio on and off and so far no negative effects.

db22

I think that you just answered the question as to why you would want to add more bass.

getakey

I can only tell the ANC effect when at a stop (idling) and under acceleration. At a level speed, road noise is greater than the engine noise even with the mics covered.

getakey

Amending my earlier reply
Probably a simple explanation
ANC creates a out of phase signal with same amplitude for noise cancellation. Adding amp plus woofer with signal from OEM woofer just amplifies the noise cancellation above and beyond the real noise. That's the hum.
Now question is why disconnecting only back mic eliminates the problem

PHUQ2

I hooked up an amp on my 2 KIcker L7 15's today and everything sounded fine .... Until I closed the door and the anc system activated. I had acura discoect the rear mic today. That stopped most of the problem. But now it seems that when I am at low speeds I can still hear it. I have noticed what looks to be a mic.gril in front of the front dome lights. Is that indeed the other mic and will that fix my problem. It is interfering with my music. Gopple-damp-it-turkey-blaster!!!!

getakey

yes - 2 mics
one in rear and the other esactly where you describe

getakey

well exactly that is

Gabe15

iTrader: (1)

Yes that was the same problem I had until I unhooked the rear mic. Doors open it sounded fine. Doors closed is when I heard the amplified bass sounds at low idle. I did not have to mess with the front mic. I need that mic for the phone anyway. You probably wont like my suggestion but you might try turning the gain on your amp down to see if you can tune it out.

BTW FYI....I initally came back to this post because I wanted to report a possible negative effect of disconnecting that rear mic. I have noticed that when listening to FM radio (AM is unaffected?) and I turn on the rear defrost my radio station goes to out. What i mean is that it goes to the sound you hear on TV when there is no signal. I would test it but I am not wriggling my hand back in above the rear dome light to plug the mic back in.

Hopefully someone else who has subs can turn on their rear defrost while listening to FM to see if its the disconnected mic or something else causing it.

db22

You probably won't like my suggestion either:
If you turn the volume up to just below breaking the glass (or eardrums) then the actual air movement in the car will defrost the windows faster than those stupid wires in the rear glass. The alternative is to use a relay to switch to XM whenever you need to defrost the rear window.
Question: If you listen to a band of 5 musicians with 5 vocals, do you really want the only background rhythm instrument (the bass) to be disproportionatly 5 times louder than everything else? If the band and/or the audio engineer thought so then they would have mixed it like that. If you think that the RL needs more bass then it's probably only to piss off the guy sitting next to you at a stop light.
OK - I don't want more bass but I defend your right to add it if you feel so inclined.