PDA

View Full Version : Stereo Help?



Hydrofoiljunky
08-17-2011, 07:19 PM
Hi guys, I have a got a quick question for yaíll. I have a Wetsounds 420 and when I have the engine off I have no noise thru the tower speakers or the inboat speakers, however when I turn the engine on, I get a loud whine running thru the inboat speakers only. I have all my grounds to the same location. I have also messed with the gains and this is really weird. I canít turn the gain up on the in boat speakers amp at all or the whine gets unbearable so it is at itís lowest setting and seems to almost get rid of the whine(You can still hear it but it isnít bad)but I can turn up the gain on the tower speakers amp with no hiss or whine at all. Can you guys recommend anything to check first?? I thought about adding a ground loop isolator but where do you run that? In Between stereo deck to the amp with the problem? Instead of messing with it for hours I thought maybe somebody has had the same problem? I was thinking a guy should be able to turn the gain up just a little on
their amps right? LOL Any help would be greatly appreciated. Thanks in advance.

Chad

mmandley
08-18-2011, 10:43 AM
If you cant turn the gain up at all on the amp my first thought is the Amp has a floating ground inside it. More or less its a bad amp now. You can test this theory buy plugging thye towers into this amp and see if they have the same whine or by moving the RCA from another amp to this one so the signal is changed. This will rule out other souces. I still feel its my first thought and you have a bad amp.

wetsounds1
08-18-2011, 01:11 PM
Chad,

what you have is refered to as "engine noise" You RCA's or amplifier is picking up that alternator whine. mmandley is right, first step is to swap the RCA's and see if it swaps the noise. If it does, then that is a bad RCA or the way it is run, is picking up noise, or the amp itself. You want to make sure RCA are not run with power cables. You want to keep them as seperate as possible. Also, make sure that the radio is also grounded where the amps are. you mention all grounds. just make sure all includes the radio, ws-420 and amps. So if it swap the noise, then it is just an RCA. If it doesnt then it could be the amp itself.

Tim
Wet Sounds

Brianinpdx
08-18-2011, 02:41 PM
Chad - often times accessories such as EQ's and other electronic items get wrongly blamed for system noise. In other cases, those very items are sensitive to grounding issues and are indeed the problem. What your hearing is the difference in ground potential between your electronics coming through your speakers. Your going to need to do some experimenting and isolate the problem. I'd say it could be any one of the amps / head unit / or the 420. Or even a bad RCA. There are some real simple tests you can do to remedy this..

A couple of questions for you:
- where are your amp gains set now?
- Have you always had noise in the system? or is this something new?
- Is this noise coming from all zones? i.e. cabin / sub / tower?


Here's what I would do:
1 - check all power cables. Make sure they are all run directly back to the battery or to a distribution block. If not, make it so.
2 - unplug the input RCA's from the amplifier to isolate the amplifier itself. power the system up and if the noise goes away, then we need to be looking up stream from the amp (i.e. the 420). if the noise goes doesn't go away, you've got ground issues with the amp so review #1 on the amp.
3 If needed, repeat this same process on the 420 by unplugging the inputs
4 - IF needed by pass the source player completely, and use a 3.5mm jack and plug the iPod directly into the 420.
5 - If needed by pass the source player and also 420 and use a 3.5mm jack and plug directly into your amplifier (be careful not to crank the iPod to 100% or you'll drive your amplifier into full clip).

What I'm suggesting is to isolate which area of your system is being effected. Once you do that, you can dig deeper and implement a solution. I suspect when you do these checks, some other little tid bit of information will present it self. It's also possible that this is a cable problem but my gut feeling is you have something in the signal path that is generating noise and everything else is reproducing that bad sound. Remember, even if you isolate the problem, don't immediately think its the device thats bad. It could just be the cabling attaching to the given device. Isolate first, then solve the problem.

Let us know how it goes. Lots of good people here that can help you trouble shoot it.

-Brian
Exile Audio

philwsailz
08-18-2011, 05:53 PM
You say you have all grounds to the same point. What about the head unit?

9 times out of 10 the head unit still gets its power through the helm power bus and people don't change it. If you have not moved your head unit power, do so. Take both the red and yellow positive power wires to the B+ power lug of your largest amplifier. Make sure the red wire goes through some sort of switch that preserves your ability to turn the radio on and off like normal. I have schematics if necessary to show you the switching options. Move the radio's negative/ground wire to the biggest amp's B- terminal. Do the same thing with the WS420.

This will remove the ground potential difference between your audio components and will get your head unit powered up by the exact same power as the rest of the stereo. This will usually take care of it.

Phil
Kicker

EarmarkMarine
08-18-2011, 06:23 PM
Phil's recommendation pinpointed it most likely. He has an excellent grasp of electronics. However there can be the more abstract causes of noise from a nasty black box HU or another audio component that doesn't have the right isolation between the RCA shields and the chassis ground or has a shield isolation value that is very different from the other audio components. Another common issue is when the RCAs are plugged in while the system is hot and it damages the fragile preouts on the head unit which is instant noise. Some amplifiers have a speaker ground that is common to the RCA shield so all it takes is a tiny shorted speaker wire strand that introduces noise into the entire audio chain. My point is, its not always so straight forward. If you try the basics listed above you will probably find the cure but if it still persists then you may need an installing dealer rather than a manufacturer.

David
Earmark Marine