Kicker kxm800.5 preamp out

[z28ke]

Most websites state that this amp has a preamp rca output, but I'm not seeing it. I have this amp running my interior speakers and a 12" sub, and would like to daisy chain to my stock kicker for the tower speakers.

The rear channel/sub out on the stock kenwood head unit produces terrible alternator/electrical noise and I haven't been able to solve it. The front output is clean, and was hoping to use that for both amps without having to use rca splitters.

Am I crazy or are there no rca preamp outs on this amp?

https://uploads.tapatalk-cdn.com/20170615/dfdec5a0d49bf8771d169461a8e2591a.jpg

https://uploads.tapatalk-cdn.com/20170615/4b74c6284b301bc79a1318063b781892.jpg

Thanks

[MLA]

The 800.5 does not, but the 400.4 400.2 do.

With that said, you will be better served with a dedicated signal for your tower am. Yes its more work to run one from the head unit, but worth it.


The rear channel/sub out on the stock kenwood head unit produces terrible alternator/electrical noise and I haven't been able to solve it.

How was this determined to be generated by the head unit, yet not omitting from the front out? Sounds like ground loop, which is not really generated by a component.

[z28ke]

I hooked the front rca channel to the tower speaker amp and it's clean.

I have all grounds tied to one battery, ran a new power and ground wire for the head unit directly to amp power source, used a higher end rca cable, and tried a inline rca isolator and nothing has cleared it up.

[BrettLee3232]

I would recommend Kicker's ZXMRLC Dual-Zone Remotes. Plus it's Line-level. Handles up to 4.5 volts and differential-balanced inputs for minimizing unwanted noise. That will allow you to have independent volume of cabin & tower speakers. Plus using the existing sub volume for the 800.5. I custom mounted mine in my ACC switches but can mount anywhere.https://uploads.tapatalk-cdn.com/20170615/55bb1c2ade6c82ceb87b8ae37ab8eeff.jpg



http://www.kicker.com/zxmrlc-dual-zone-remote-level-control


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[David Analog]

Most websites state that this amp has a preamp rca output, but I'm not seeing it. I have this amp running my interior speakers and a 12" sub, and would like to daisy chain to my stock kicker for the tower speakers.

The rear channel/sub out on the stock kenwood head unit produces terrible alternator/electrical noise and I haven't been able to solve it. The front output is clean, and was hoping to use that for both amps without having to use rca splitters.

Am I crazy or are there no rca preamp outs on this amp?

https://uploads.tapatalk-cdn.com/20170615/dfdec5a0d49bf8771d169461a8e2591a.jpg

https://uploads.tapatalk-cdn.com/20170615/4b74c6284b301bc79a1318063b781892.jpg

Thanks

So the selective HU noise you describe (only on SOME preouts) is common and in most cases is easily repairable. But first, Never plug-in or unplug RCA connections while the audio system is powered up. Okay, so grab a multimeter and make this check. Unplug all RCA cables from the HU. You should get full continuity between the noise-free HU RCA ground shield and the HU chassis. You may not get continuity between the noisy HU RCA ground shield and the HU chassis.

[z28ke]

Ok thank you! I already looked up an external repair by soldering a fused ground wire to each shield and grounding to the case. Thanks again!

[David Analog]

Ok thank you! I already looked up an external repair by soldering a fused ground wire to each shield and grounding to the case. Thanks again!

That's great and I hope for simplicity sake that this is the true cause. Don't forget to test first before leaping into the fix.

[z28ke]

To give closure to the thread, this fixed the problem!

[BrettLee3232]

To give closure to the thread, this fixed the problem!

How did you do it?


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[David Analog]

How did you do it?


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The internal traces on the HU RCA grounds are very fine. These internal traces are typically fused to prevent more serious damage to the HU. But the fused links aren't really serviceable. This link is often broken by connecting and disconnecting RCA cables (at either end) while the audio system is powered up = big mistake.
The scheme is to reference all audio grounds back to one location, the HU, in order to avoid ground loops. Generally all other amplifier and processor audio grounds are above ground and don't reference to true ground, other than through the HU. However, when this ground termination is interrupted, noise becomes a problem specific to that RCA set, whether front, rear, or sub/non-fading. To remedy you connect the exterior RCA shield ground to the HU chassis ground, which is true ground.

[BrettLee3232]

The internal traces on the HU RCA grounds are very fine. These internal traces are typically fused to prevent more serious damage to the HU. But the fused links aren't really serviceable. This link is often broken by connecting and disconnecting RCA cables (at either end) while the audio system is powered up = big mistake.
The scheme is to reference all audio grounds back to one location, the HU, in order to avoid ground loops. Generally all other amplifier and processor audio grounds are above ground and don't reference to true ground, other than through the HU. However, when this ground termination is interrupted, noise becomes a problem specific to that RCA set, whether front, rear, or sub/non-fading. To remedy you connect the exterior RCA shield ground to the HU chassis ground, which is true ground.

I guess a picture would help me understand lol


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[z28ke]

https://uploads.tapatalk-cdn.com/20170620/a60d5f051051217ef0a84c7650cf5bf0.jpg

Here is a photo I found online.

[David Analog]

https://uploads.tapatalk-cdn.com/20170620/a60d5f051051217ef0a84c7650cf5bf0.jpg

Here is a photo I found online.

Looking at that photo, it seems so improbable that someone would have to do such a bizarre thing as a fix for noise. Rarely it is required.

[BrettLee3232]

Is this similar to a ground loop isolator? I know everyone says GLI are temporary fixes but usually everyone says they work. I've noticed more and more I have more buzz when engine is off.


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[MLA]

Glad to see you isolated the noise and found the fix rather than use pass thru- RCA ports for a completely different zone, and 2, glad to see it fixed and not with the use of a GLI.

[David Analog]

Is this similar to a ground loop isolator? I know everyone says GLI are temporary fixes but usually everyone says they work. I've noticed more and more I have more buzz when engine is off.


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Nope. You could say this fix is the polar opposite of a GLI. Keep in mind that if you have continuity between the HU RCA ground shield and the HU chassis, as you should, then the fix shown in the photo is not needed. This fix is not a band-aid like a GLI (a GLI leaves the real problem intact), instead the fix shown is a correction for something that was broken, and restores the HU back to normal status.