LC2i and Aftermarket Sub in B8 non b&o

[TimNGobbles]

I am looking for some help / suggestions / confirmation on my subwoofer addition.

Here are the basics.
2012 Audi A4, base stereo with navigation


I have an Infinity Kappa 100.9w subwoofer set at the 4 ohm level with a recommended max rms of 350w (crutchfield link http://www.crutchfield.com/S-TOp1aa4jzKl/p_1081009W/Infinity-100-9w.html). The subwoofer is in a sealed .75 cf box.

To power that I have it connected to an Alpine MRX-M50 that shows being factory tested at 340w rms at 4 ohms (crutchfield link http://www.crutchfield.com/S-1NCG0HvVQVV/p_500MRXM50/Alpine-MRX-M50.html).

I used an Audiocontrol LC2i to tap into the factory subwoofers.

I had this same set up, minus the LC2i line out converter, in my B5 Passat connected to an alpine head unit. It seems that I need to turn my amplifier gains up to about 2/3-3/4 and increase my amplifier bass eq to near the maximum to get enough bass to hear it in the A4 vs in the Passat. When I say enough bass, I mean enough to have it blend with the music. I tend to listen to my music at a low volume. I don’t appreciate any distortion with the setting and volume levels I use.

I have the LC2i supplying the amp through the “main “ outputs vs the bass outputs so I don’t have the LC2i processor adding more junk. I need to have the main selector output level on the LC2i set to the maximum in order to get a decent amount of sound from the amp and the sub. I tried to use the bass output on the LC2i but had a similar issue. I only have my tapped factory speaker wires going into the right +/- inputs on the LC2i.

In the car I have my MMI with the subwoofer setting set to the middle level and my bass setting is set 2 past the middle level. I can turn up the bass on the MMI and it does increase the bass response in the car but it also increases the bass from the other speakers and sounds crappy.

So I guess my question is: am I going to damage anything with setting the LC2i and the amplifier adjustments to near maximum levels, as described above, to listen to my music at the low levels I prefer?

My other problem is I get a single bass pop when I shut my car off. The popping noise is lower if I turn the output level down on the LC2i. I have my LC2i powered by a tap-a-fuse connected to a switched fuse spot in the rear of the car. The LC2i also supplies the remote turn-on for the amplifier. I haven’t tired but I think giving the amplifier its own remote turn on from a switched source might eliminate this issue. Any suggestions?


Thanks for reading, sorry this got long.

[RPMtech147]

Your first issue is you need both left and right inputs to the LCI. Yes, I know the subwoofer is MONO but your total input volume is 50% of what it should be...Either connect your left inputs to a left speaker, or if your lazy, connect a jumper from the right + and - 1 to the left + and - should give you double the input volume to your amp. It's the same thing as having one of the RCA's disconnected at the amp, 1/2 the input volume.

Also, I'm pretty disappointed at how bad alpine is over-rating their amps now-a-days. 350 RMS watts at 4 ohms for $200. I doubt it. Nothing has changed. A decent AMP costs $1 per RMS Watt or more @ 4 ohms. I have a similar setup in my BMW and have the Baby Kicker 1 Channel Amp Kicker 11DX250.1 pushing a DVC 8ohm Diamond 10" bridged to 4ohms and it's just barely enough to kick that heavy 10. Your amp should be just a bit more then my kicker at 4ohms not 3X the wattage. If your like a lot of guys that dont like turning up Amps more then 1/3rd the way to try and keep THC down then your going to need a larger amp.

[TimNGobbles]

My other problem is I get a single bass pop when I shut my car off. The popping noise is lower if I turn the output level down on the LC2i. I have my LC2i powered by a tap-a-fuse connected to a switched fuse spot in the rear of the car. The LC2i also supplies the remote turn-on for the amplifier. I haven’t tired but I think giving the amplifier its own remote turn on from a switched source might eliminate this issue. Any suggestions?


So the cause of the pop was from the LC2i's GTO option. The GTO is suppose to turn on the unit when it senses input from the speaker wires eliminating the need for a remote in wire. I turned off this feature and just hardwired a switched remote in wire and life is good.

I did play with my settings on my amp and LC2i and have found a decent balance, or at least good enough for a nonaudiophile like myself.

Hope this helps someone else.

[V1nny]

don't use signal from main speakers, use the subwoofer signal, either pre-factory amp, or if not possible for any reason, post-amp with speaker level converter.
Also try to reverse the new subs polarity ( i know sounds crazy), as there is a chance that your new subs are fighting the acoustic output of the factory sub because of placement, and they cancel most of each other output. Configuring multiple subs is not supposed to be an easy task.