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

[bbuhtz]

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

[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.

[bbuhtz]

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.

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

[bbuhtz]

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.

[08LSV]

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....

[bbuhtz]

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.

[08LSV]

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.

[bbuhtz]

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. =(

[bbuhtz]

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.

[bbuhtz]

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.