View Full Version : New sound system, need help

04-07-2012, 07:51 PM
I finished my new sound system installation last night at 1:30 AM. Tested it out in the garage, and everything sounded great. I put the boat in the water today and started it up, and I had a horrible interference whine coming from all the speakers. It sounded worse on the tower speakers, but that might be since I have the gain set higher on those.

Here's what I installed and how: 12" RF P3 sub powered by RF Prime 1000W RMS amp. I mounted this in a custom made box underneath the port side bench seat. I lost some storage, but couldn't find a better place to put the speaker with box. I mounted the amp to the side of the box. I took power from the blue sea distribution, so the power gets cut when I turn the distributor switch. I ran 1/0 battery cables to distribution blocks also mounted on the box.

I installed 2 rev 8's on the tower. I was originally going to get rev 10's, but decided not too based on size. They are powered by a RF R600-4D, bridged to give me 300W RMS X 2. I'm powering the in boat speakers with an Alpine 500PDXF6, which gives me 150W RMS X 4. These 2 amps are mounted above my batteries. I pulled down the carpet and glued/screwed in 2 15x30" cutting boards to add screw depth.

I ran 8 gauge cables to the tower amp and 6 gauge cables to the in boat amp. The power, ground, and signal wires stay low and come up on the front sides of the amp. The speaker wire and RCA jacks come down the rear side of the amps away from the power cables. They do run by the signal wire coming from the head unit for a little bit.

I also couldn't find shorter RCA cables, so the extra is looped behind the head unit. The RCA cables for the sub do run back to the sub amp along side the power lines for the other two amps. They are getting their signal from the pass through plug in on the tower speaker amp.

I have several ideas on what could be causing my issue:
1. The sub RCA cables could somehow be backfeeding the alternator excitation back through to the other RCA signal cables.

2. My signal wire is is causing the interference from the short section where it is running along side my speaker and signal RCA cables.

3. The extra looped RCA cables are the issue, which I'm doubtful.

I guess I could unplug my pass through RCA cables going to my sub to see if that fixes my issue. I just thought of that, and will try it next time I'm out.

Here's some pictures of my install. Let me know what your thoughts are to fix my issue.

04-07-2012, 08:38 PM
Also, I ran 2 sets of RCA cables from my head unit. The front left & right go to the in boat amp and the rear left & right go to the tower amp, and then the feed through goes to the sub amp. I guess I could mess with the fade to see if one direction gets rid of the issue, or if unplugging one set of RCA's makes the issue go away.

04-08-2012, 12:21 AM
Do all your power lines and ground lines tie in at the same spot? Including all amps plus the head unit? If they don't they should so start there.

04-08-2012, 12:50 AM
The amps all go to the same spot. The head unit is still using the factory power and ground wires. I didn't touch those.

04-08-2012, 11:29 AM
I'm going to run dedicated power and ground to the head unit. Can I tap into power and ground from my tower amp, or do I need to run dedicated wires all the way back to the distribution box?

04-16-2012, 11:50 PM
is that power cable i see wound up there? if so that makes an induction coil and that will pick up noise real fast as well.

04-17-2012, 11:16 AM
No, it's RCA cable. I couldn't find any shorter length locally and didn't want to wait to order one.

I rewired the head unit to the same power and ground location, and that fixed most of the noise. There is still a little left, and when I unplug the sub RCA cables, it goes away. It must be backfeeding from the pass through into my signal inputs. I moved the sub RCA cables away from the power and grounds, but haven't tested it on the water yet. I'm going out tonight to test it out, and get a little wakeboarding in.

Thanks for the help.

04-17-2012, 12:22 PM
again try unwinding those rya cables, even twisted pair will have a hard time canceling the noise when wound in a coil. if that works and you still need to do something with that excess cable, wrap it in a figure 8 style, this will allow for the cancelation provided by the twisted pair in you rca cable.

04-17-2012, 12:38 PM
Are the distribution blocks for power and ground for all three amps on the sub box? If so, I would move those to keep the lengths as short as possible. Is your Blue Sea near the Batteries? The key with power and ground is to make the runs as short as possible, and since the whine will be most prominent in your boat and tower speakers, then make those amps have the shortest runs.

Also, what head unit are you using, and if it is not the stock unit, does it have 4V preouts? And while you are at it, you might want to add one of these to control your tower speakers.
https://www.cartoys.com/products/product.cfm/cartoys/PAC_LC1_Universal_Remote_Level_Control_via_RCA_Aud io_Interconnect__LC_1_/