Ok so I am in need of some help with my stereo setup. I had a modified stock system that sounded pretty good. The interior was lacking some power and I wanted to add another amp to help get my speakers a little more juice (and my sub amp died). Now I am getting feedback out of my 6 interior speakers. When the boat is not on or the exhaust fan is not running it sounds good. But as soon as you kick on the fan or turn the boat on you get a hmm out of all 6 speakers. Also my problem is I am out of RCA outs on my head unit so I need help there too. This is what I had and what I have now. <BR> <BR>03 SAN Team 210 (old setup) <BR>Stock tower, factory kicker interior, 12in sub in custom box. <BR>KX300.4 – powering 4 interior, head unit powering 2 bow speakers. <BR>Tower speaker amp…dunno what it is <BR>Sub amp (died) <BR> <BR>New setup <BR>KX300.4 bridged on 2 channels for 12 <BR>Tower speaker amp <BR>JL M6450 powering 6 interior <BR> <BR>I moved all the old speaker wires off the 300.4 and put them on the JL amp, pulled the bow off the head unit. Routed new 4 gage power and ground cables to the JL amp. The JL amp needs a Y adapter or 2 sets of RCA’s going into it to feed all 6 channels. When I was using a radio shack Y adapter RCA I was getting terrible feedback. I changed it to just run 4 speakers and it is not as bad but I still get interference. I have no more RCA outs on my head unit, and I don’t have any outputs on my amps. <BR> <BR>So the ? is, what should I try to get rid of this interference? My RCA cables powering the JL are thick monster cables. Could it be the thickness of the wires feeding the speakers them selves? That is all stock stuff, I am stuck here...and confused being i had no problems before. <BR> <BR>thanks sorry for the long post

Chris - sounds like you got a couple of things going on here but that whine you are hearing is probably a ground loop coming from wherever it is your amplifiers are PWR/GRND connected. <BR> <BR>Give us some info on where you ran the connections and we can go from there. <BR> <BR>-Brian <BR>Exile Audio

All your powers/grounds including your HU should be to the same place. i.e. If you have a second battery and the HU is still on your starting battery (typical from the manufacturer) while the rest of your equipment is off the house bank.

All my amps are grounded to my rear battery. I think...my front battery is the starting battery. Anyways, yes all the amps are on 1 battery. I was reading more yesterday and saw that as well. That I need to ground my head unit to the same battery or ground as the amps. I am going to give that a shot this weekend. <BR> <BR>Can I piggy back a ground from the head unit to my M6450? Or should I run a dedicated ground from the head unit all the way back to the battery? <BR> <BR>Thanks!

You can tie both your power and ground into your amps power and ground but you'll need either a switch or a relay depending on how you turn it on now. I use my ignition so I had to do a relay. Phil White has posted a diagram a couple times here on WW.

to cut out the interference will i need to tie both the power and ground? Or can i just do the ground?

Chris, <BR> <BR>Its important that the HU, amplifiers and all audio electronics reference the same battery. <BR> <BR>But in a simple dual battery system with a dual battery switch, all of those positives including the helm buss and alternator feed should access the same common post of your battery switch. The positive posts of each battery should only be connected to the battery switch positions 1 &amp; 2. This scheme automatically resolves any loop issues. <BR> <BR>All grounds are common. Its easy when things get installed or moved around to overlook a ground. Make sure all connectors are solid. Particularly important is your ground from the battery(s) to the engine block since this represents your greatest mass. <BR> <BR>To answer your question, you can attach your HU positive and negative to or very near the 6450 terminals, in fact, its preferred. A low resistance reference between your HU and largest amplifier is the most critical link for several reasons. <BR> <BR>Something else, when your batteries are separated by the length of the boat its especially important that the connecting cables are larger gauge and commensurate with the distance. <BR> <BR>David <BR>Earmark Marine

Chris - Let us know how it turns out. If these suggestions dont work we can chat on the phone and get you sorted. I have a hunch you'll be good to go. <BR> <BR>-Brian

Thanks guys, I really appreciate all the help. I am going to try and sort it out again this weekend...if we dont get too much rain and I can get the boat out. I will let you know how it goes. <BR> <BR>Thanks again to all!!