Stereo Troubleshooting (noise/feedback through amp powered speakers only)

Okay I'm going to try and lay this out as much as I possibly can to narrow down my issue.

Problem: Noise through the tower speakers only (amp powered, zx200.2 powering stock towers, and dx200.4 powering 2 polks)

I am exactly wired up with Al's diagram, nothing different, other than I have a 3 bank Prosport charger individually wired to the three batts. (page 2 of link below)
https://forum.moomba.com/showthread....R-Combo)/page2

After wiring the ACR and three batts, I later installed a new HU Kenwood KMR 440 as well as a KCA RC 107MR remote. Everything was working perfectly (no noise through speakers, happy sounding boat). I then installed a Krypt KMA 4200 EQ, wired it up correctly and again everything was good. And by good I mean speakers had no noise, the eq worked fine, the boat sounded great! Went up to Lake Sammamish to meet up for the pro surf comp, I put the boat in the water, we started our treck out boarding, but I noticed none of my tower speakers were working. The Krypt 4200 eq was shot (blowing fuse after fuse)... that is a different story but in all the eq was done, so instead of not having tower speakers all day, I decided to just use the old RCA cables that I still had in the port compartment, plugged them up, just how I had them plugged in before I installed the Krypt 4200 eq, and that is when I started experiencing a lot of noise, so much to the point I couldn't use the towers at all. (by noise I mean hissing, w/ boat turned on or off, krackling, just about the worst noises you ever want to hear out of a speaker) So for the day I just disconnected the RCAs and carried on with my day.

Lately I've been trying to do a little troubleshooting and me being an ME, not an EE or stereo tech, need some other options to explore. So far I have tried wiring my HU ground to the amps ground, that didn't work, I was still experiencing noise. Next I went through my wiring, checking for any loose connections, still nothing and I continued to have noise. I've tried my old HU and installed that and also had noise. I've tried different RCA cables of higher quality, not super expensive but not cheap ones either, nor are they ground isolated RCAs and still had noise. I've also seperated power and ground wiring from the RCA's and also experienced noise. What else... stereo bank batteries are fully charged, the zx amp is older but the dx amp was just taken out of the box brand new so I'm ruling out the amps are bad.

While I'm troubleshooting the boat is sitting in my driveway turned off, either plugged in to AC charger or not, I've tried messing with keeping the Prosport plugged in and unplugged, that doesn't seem to mess with anything. I would still like to try different RCA cables than the ones I have thinking that may be it, but before I buy more I figured I'd try and ask the forum, maybe some of you have had similar issues or have some different options to explore. I will be receiving a new Krypt 4200 eq and am hoping that putting that back it will fix the noise but it may not get here in time for our week long vacation with the boat next week. I would hate to not have my tower speakers for a week, so please any ideas, suggestions, shoot them at me. Thanks

After reading your post I can't tell if you fully removed the EQ from the mix? If not definately do that and test. Another thing to test would be the head unit itself. Get yourself a mini pin to rca cable, mini pin for the ipod and rca's for the amp. Disconnect the rca cables from the tower amp and plug the ipod directly into the amp rca ports. Make sure the volume is down before you do! Now see if it plays without the hissing noise. If the eq is out of the mix and it still does it then the HU is suspect.

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Originally Posted by Razzman

After reading your post I can't tell if you fully removed the EQ from the mix? If not definately do that and test. Another thing to test would be the head unit itself. Get yourself a mini pin to rca cable, mini pin for the ipod and rca's for the amp. Disconnect the rca cables from the tower amp and plug the ipod directly into the amp rca ports. Make sure the volume is down before you do! Now see if it plays without the hissing noise. If the eq is out of the mix and it still does it then the HU is suspect.

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Yes the Eq is out of the mix as of right now, I sent it back for a replacement and haven't gotten it yet. I'll try hooking up an ipod tomorrow through my mini pin cable, thanks, didn't think of that one, good idea though. I did try swapping out HU's and I still had the same noise, so I was kinda leaning away from that being the issue... can't imagine both are bad, but you never know I guess. Thanks Razz

Okay, so I hooked up my ipod to both of the amps through a mini pin/RCA and no noise. Soooo, must be either the HU or the RCA's I've been trying. As much as I hate to do it, I may reroute one of my better RCA cables that was run from the helm where the eq was to the port side compartment to hook it up to the HU and then to the amp and see if that makes a difference. If it does, then its the RCAs that I have been using to troubleshoot creating the noise and/or the HU. If it is the HU, should I try rewiring the HU completely or am I out a HU...? and in this case i would be out two HU's since the other HU I tried was also creating noise. I'm crossing my fingers its the RCA cables here, since the HU is basically brand new.

I have had what seems to be the same issue a few times in the stereo systems in both vehicle and boat. The first time was in a truck when I was 16 and it turned out to be the ground wire on my amp and head unit. Many other times it has been inferior RCA cables. The more recent time was in my boat and it was again a poorly insulated/bad RCA. I have definitely learned my lesson over the years with not buying quality RCA's. an easy test before rerouting everything would be to buy some new RCA's packaged in a way that you can open them without destroying the packaging so they are returnable if they don't solve the problem. Then just tag and unplug your routed ones and just put the new ones in laying out on top of everything. Be sure to hook up a fake a lake or put your boat in the water so you can test it running, as the electrical currents and vibrations make a huge difference with the RCA insulation. If the engine was not running when you tested the ipod connector and other parts that may be why it doesn't happen in your driveway, but happens when your out on the lake with the engine running. Make sure you run the engine and audio system long enough for it to warm up and have a steady flow of current to be sure. Hope this helps, I know how it feels to get to the lake and have something not working. I had a major ballast failure yesterday on the lake when my 1100lbs bag emptied itself in my boat..... Luckily it happened at the end of the day, but sure made clean up a pain....

Good idea returning the RCA's... I'm almost positive its the RCA's now that I think about it more, seeing as i was experiencing the noise with both HU's, and the noise is almost like I can hear my HU thinking. For example, when I go to the CD function, through the speakers you can hear the CD winding up to speed and when music starts to play, its a really poor quality sound. The difference of noise from being on the water and in my driveway is i just get a lot more poping and krackling on the water, versus hissing and an assorment of feedback through the speakers in my driveway, engine off. Plus closest lake to me is about 30min away. The thing that boggles me is how come I wasn't experiencing this noise prior to installing the eq... With the eq now out of the picture, it is wired up exactly how it was before (same RCA's, wiring, etc.) and i wasn't experiencing noise. I'll grab a good set of RCA's tomorrow like you said, ones that i'd be able to return, and try them out. Thanks for the idea.

If there was something wrong with the EQ causing it to surge enough electricity to keep blowing fuses it may have overheated one of the RCA's. It may have even melted some of the insulation. I hate to say it but if the RCA's are not the problem you may have to retrace all your wiring and look for bad/melted spots. If so I would start with the ground wires.... Hope the RCA's are the easy fix for ya.

Okay well I went and purchased a new, high quality RCA and plugged it into the HU and amp and I am still experiencing the noise... so this either means both HU's are bad, or somehow the wiring of the HU is affecting the RCA outputs of the HU? The inboat speakers are being powered by the HU and they sound fine, the noise is only coming from the RCA outputs of the HU. I am going to go disconnect everything from the HU and rewire it, hoping to solve this issue. Anyone know the cause of this? Its weird how BOTH HU's would produce the same noise from the RCA outputs and not the inboat speakers. Can bad wiring be the cause of sending noise through the HU and out the RCA's? I'm going to go out and try rewiring since I'm at a brick wall here and leaving for a week vacation with the boat tomorrow, I'm hoping I dont have to spend the week without tower speakers. =(

Okay... after trying to rewire everything I still have noise. But I did notice something... when I stepped back behind the tower speakers to listen to the noise at a low volume setting, touching the tower made it worse. soon as I let go of the tower the noise was still there, just not as bad. So I messed with putting my hands on and off the tower increasing the noise and decreasing. So I decided to hook my mini pin/RCA cable back up to the amps to see if I could replicate the noise by touching the tower and I had no luck. Crystal clear out of all tower speakers with the mini pin/RCA cable and ipod. I'm so frusterated with this damn thing, looks like for the trip I will just keep the mini pin/RCA hooked up to the amps to use for wakeboarding and use the inboat speakers for surfing and chilling. I'm going to settle with my new HU being the problem unless someone has a different idea.

I love a thread to myself... after digging around more on the web, looks like some head unit's internal grounds go bad and cause noise through speakers like you can hear the HU thinking, spinning the CD, some assorted poping, etc. This only affects RCA outputs, hence why I'm not hearing noise through my cabin speakers. Unfortunately I think I've solved this problem and I believe that my HU should still be under warrenty so I'll try to get a replacement. If not, that thing is coming apart and I'll fix it myself. If you stereo experts think otherwise, let me know.

Hey man sorry you didn't have any luck with the RCA's... The fact that when you touch the tower has an affect on the sound would lead me to start checking ground wires first, then tower speaker wires. Just a thought but does your head unit allow you to turn on/off its internal amp? I have the Kenwood 700 and it allows me in the settings menu to turn the internal amp off. I have mine off so that I get less distortion at higher volumes. It is a long shot but may be worth a try since your heading out soon.

I think your on the right track with the HU but it concerns me that when yuo touch the tower it changes the sound of the speakers. This is telling me its shorted on the tower and the tower is acting a huge antenna. I would also pull the speakers off and inspect the wires where they go in the tower. Make sure it hasnt rubed into the wire insulation and is shorting or almost shorting. Normaly a short o the tower would kill that speaker ot the amp but its might be just enough to radiate noise threw the system.

I was also thinking the same thing, that maybe the tower rubbed into the wire insulation and was shorting. But when I connected my ipod through my mini pin/RCA to the amps, I couldn't replicate the noise for one, and touching the tower had no additional affect. It was crystal clear, even jumping around in the boat, shaking the tower, anything I could do to get some noise out of the system if it were a speaker wire but I couldn't. The noise is only happening when the HU is connected to the amps. Ipod connected directly to the amp --> no noise.... HU connected to the amps --> noise. I will inspect the speaker wires regardless in the morning, just so I can positively rule that out and what do I've got to lose anyways. Thanks for the help.

HAHA i just noticed your PNW area. How close are we? LOL. Anyhow yea i think your HU is prolly bad then if you got good sound with the IPOD directly connected.

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Originally Posted by mmandley

HAHA i just noticed your PNW area. How close are we? LOL. Anyhow yea i think your HU is prolly bad then if you got good sound with the IPOD directly connected.

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Thats what I'm thinking as well. I wonder if somehow because the internal ground of the HU is somehow bad, that by touching the tower I'm acting as some sort of grounding and thats why I'm introducing much more noise. What a PITA troubleshooting that was, specially with a newer HU. I'm up near Bremerton, WA, I'd say we're a good 3.5 to 4 hours away. Thanks for the help.

I have finally tracked down the problem. It was indeed my damn HU. I received my new Krypt 4200 EQ today and installed it back into the system. First I tried it by just plugging in my mini pin/RCA through the EQ to see if I had noise through the tower speakers. The speakers sounded crystal clear. Then I plugged in the RCA from the HU into the EQ and I had the noise! Same noise I've been hearing all along. Sooo, with all my frustration carrying on and a vacation coming up, I couldn't go without towers, so I ran down to car toys and picked me up a new Kenwood KMR 440U. Brought it back home, replaced the currect HU with the new one, hooked everything up, and wala! NO NOISE... So it turned out to be a bad HU. I hope no one ever has this problem, cause it was a PITA tracking down. I guess the worst part about it was in the back of my head I really really didn't want it to be the HU that I had just installed in the boat 2 months ago. I was trying to blame it on everything else, and because not everyone just has extra HUs laying around. I fortunately had my stocker, but for some reason it was reproducing the noise as well, so that must be a bad HU as well.

Hopefully this thread will be useful to others that experience noise through their external amped speakers. I'm not saying all noise is going to be the HU, but if you have similiar noise as I was experiencing, don't be afraid to blame it on the HU after checking everything else. The noise I experienced with this bad HU is while on the water, there was hissing, poping, and extreme krackling as the boat was rocked and bounced around by wakes. With the boat out of the water I was experiencing hissing, as well as being able to almost hear the HU thinking, like I've said before, CD starting to spin, changing songs on the CD, etc.

The HU is still under warranty, so I'll be sending it back for a replacement. The new RCA ($150) I was able to return. I may return this other HU I have, or keep for a spare. In all I don't believe I'm down much on $$ from troubleshooting, so all is good. I'm happy and ready for a week vacation! Anyone wanna buy a boat? LOL

I am glad you found the problem and glad you can return the RCA's. $150.... man that was one hella high quality RCA.... I just meant not the $10 ones from wallyworld. LOL! Again though I am glad you got it fixed. Have a fun trip!

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Originally Posted by 08LSV

I am glad you found the problem and glad you can return the RCA's. $150.... man that was one hella high quality RCA.... I just meant not the $10 ones from wallyworld. LOL! Again though I am glad you got it fixed. Have a fun trip!

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Thanks! Yeah I've always bought high quality RCAs, makes a difference. Thats why at first I didn't think it was the RCA's I had. Thanks for the help!

Thanks for the updates. I have been following this thread as I am suddenly also getting a high pitched whine thru my stereo. I am using all three sets of preouts, one per amp times three amps, and with the volume on the HU at 0, there is a very audible high pitched whine coming thru each zone (towers, cabins, sub) and with the stereo playing, there is an occassional loud popping sound as well. This is with the engine off. With the engine running, it's suddenly picking up alternator noise as well. Going to Car Toys today to pick up a replacement, probably going with the KDC-x395. I got 3-1/2 years out of the last unit and hope this new one will last longer.

Well I returned from my vacation and I had zero problems with my audio system, so I am a happy camper! Sounds like your having a similar issue as I was experiencing cab. Let us know if your new HU got rid of the noise. I never did do any troubleshooting with the boat in the water or with a fake-a-lake, so I'd be curious to know if that is some additional noise when the HU's outputs go bad. Kinda like the additional noise I had when touching the tower with my hand.

After going back and forth between a head unit or the Clarion EQ, I decided to just go ahead and replace the HU. So last night, I installed the Kenwood eXcelon KDC-x395 and took the boat out on the water today for a full day of testing.

With the old head unit, an eXcelon KDC-x692, I recently started having horrific whining noise even with the volume on zero and the engine off. And it was audible in all three zones so it was coming through all three sets of RCA's. I was also getting horrible alternator noise thru the speakers when the engine was running. Also, my remotes were working sporadically at best - for example, if I pushed the volume up button 15 times, it might respond once.

Well, I am happy to say that the new head unit took care of all my troubles. No more noise, either with the engine on or off, and both my remotes work perfectly again! I even replaced one of the remotes this summer thinking it was faulty but it turned out to be the head unit.

I really like this new HU - it can control your iPod/Iphone or you can control it thru the iPod. And I can now pause or skip to the next song on the iPhone thru the remote! Before, all I could do was control volume and mute.

Worked great all day - I am a happy camper! So if you are experiencing some of the symptoms I described above and you've checked all your wiring and it's all good, then it could very well be your head unit.

Al

Insert whistling (told ya so) sounds.

-Brian
Exile Audio