DiyMobileAudio.com Car Stereo Forum banner

1 - 20 of 27 Posts

·
Registered
Joined
·
35 Posts
Discussion Starter #1
Okay, so I'm getting retarded line noise from my front speakers right now.
I have them wired up with 14ga. speaker wire, to the amp in my spare tire well. I also have an LOC in the spare tire well, that is taking the rear speaker signal for the amp (I haven't had time to wire up the other LOC for the front speakers).

The battery for the car is also in the trunk. The power wires are run on one side of the tire well, and I have the RCA's on the other side.

Would the RCA's themselves be the problem? I tried switching from el cheapo home audio RCA's and put in fancy Monster shielded home audio RCA's but there was no difference.

Do I simply need to pick up a set of RCA's designed for use in car audio?
 

·
Registered
Joined
·
17,149 Posts
if the LOC and amp is in the trunk then why are RCA's running down the side of the car? ?

Can you describe the noise?
 

·
Registered
Joined
·
35 Posts
Discussion Starter #3
They're not running down the side of the car, sorry.

They're running down one side of the tire well, so that they're not near the power wires.

With the car off: No volume = minor static.
Car on: Loud, high-pitched whining, lots of static.
 

·
Registered
Joined
·
216 Posts
Where is the amp grounded? How long is the ground? What awg is the ground wire? Did u sand down to the chassis?

U might want to try a little trick i picked up from a friend when dealing with inexpensive LOC's.. Take some very thin wire and wrap it around the female ends of the LOC and ground it.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #6
Im not sure what you mean by ground loop isolation. My line out converter is grounded directly to the battery as is the amplifier. amplifier is wired with 8 AWG and both ground and power runs are approximately 2 feet.
 

·
Registered
Joined
·
17,149 Posts
Try disconnecting the ground wire and use it fully isolated. go at it easy in case it trying to sink some power to ground, it shouldn't be though.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #12
I disconnected the LOC ground wire, and it dind't change anything. I'm going to wire up my other LOC, and see if I'm still having issues with a different one.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #13
Okay, so I installed my other LOC, wired it up to my original front speakers, and I'm getting the exact same noises. What's going on?
 

·
Registered
Joined
·
27 Posts
Here's some quick info to what your having. I had the same problem too for a bit.
Ground loops and engine whine cause common problems such as a high-pitched whine that varies with engine RPM's, various thumps while changing tracks, turn on/off thumps, etc.

There are various protective measures to take in order to decrease the likelihood of experiencing engine whine and ground loops.

* Shielded RCA's
A good pair of shielded RCA's may be the easiest way to avoid engine noise. Don't use patch cables or other el-cheap-o RCA's that are unshielded. I'm not saying you need to invest a small fortune in RCA cables, just make sure they are shielded.
* Proper head unit ground
This is perhaps the most common source of engine noise. Many times factory head unit grounds are poor. Relocating the ground wire or adding to the existing one will help reduce or eliminate ground loops.
* Proper amplifier ground
If none of the above have worked, check the ground for the amplifier. Make sure it is grounded to the frame, battery, or other substantial metal surface. Make sure the metal is good 'ol fashioned detroit iron. Many cars use metallic alloys or composites that aren't very conductive. Avoid those at all costs.
* Wire routing
Some claim this next fix is BS, and others swear by their grave that it works. But run your RCA's and power wires at least 18" apart. I route my RCA's on one side of the car, and power on the other. Couldn't hurt.
* Grounding the RCA's on the head unit
Many have had problems with Pioneer head units because of a poor internal RCA ground. To remedy this, simply wrap wire around the RCA's and screw the wire down to the head unit's chassis like so:


Thanks to Ultimate157 for the image.
To view his thread on this subject, click here.


Please note: While ground loop isolators are tempting to use as a quick fix, I generally don't advise people to use them because they simply cover up the problem instead of solving it. Only use ground loop isolators as a final resort is none of the above fixes work.
If that isn't it. What size is your power wire and your ground wire?
 

·
Registered
Joined
·
35 Posts
Discussion Starter #15
Power & ground wire IIRC are 4AWG. Both are >24" runs, connected direct to the battery, with soldered eye-hole connections, bolted to the battery terminal.

I'm going to try relocation the factory headunit ground, and see if that makes a difference.
 

·
Registered
Joined
·
27 Posts
Wait your amp ground is connected to the battery?? That should be bolted to the chassis. 18 inches or shorter. My is like 23 inch because my amp is in a weird spot and I'm not pushing a lot power.

Yeah your HU ground needs to be ground to the chassis. The stock one isn't really made for aftermarket HU what's power by an amp.
 

·
Registered
Joined
·
1,485 Posts
Wait your amp ground is connected to the battery?? That should be bolted to the chassis. 18 inches or shorter. My is like 23 inch because my amp is in a weird spot and I'm not pushing a lot power.

Yeah your HU ground needs to be ground to the chassis. The stock one isn't really made for aftermarket HU what's power by an amp.
You read much? The battery is in the trunk, and its a factory HU with LOC...c'mon, this isnt even a long thread!

READ!


and learn some damned syntax!
 

·
Registered
Joined
·
1,357 Posts
I'm going to make some guesses.

In my experience in car audio, passive LOCs are usually transformer based. Those transformers can pick up EMI out of the air - from other vehicle systems, etc. This doesn't affect sub-only installs, but it sounds like you have a full-range install.
(BTW, many of those passive LOCs have piss-poor frequency response when you test them : )

That particular LOC LOOKS like Stinger's knockoff of the old AudioLink LOC, which wasn't bad (it does use transformers and a lot of attenuation). The ground wire is there as an option, just as you used it, to see if it helps. Sometimes connecting it to the chassis of the unit generating the speaker signal helps (if those speaker wires come from the HU, for instance, touching that LOC gnd wire to the HU chassis can help).

I don't know what car you are in or what system it has from the factory. One problem I have seen in other cars is when someone takes a transformer LOC meant for speaker-level voltages (so it has a lot of attenuating resistors as well as the transformers) and uses it accidentally on a low-voltage balanced signal (let's use the signal between the HU and the OEM amp in an Acura TSX as an example - I don't think you have a TSX since that signal never gets to the trunk).

So the LOC does pass a signal, but it attenuates it to the point where you have to turn all your gains way too high to hear sound, and your noise floor goes into the toilet and you can hear everything.

I may have missed this, but does your noise vary with RPM?

If you unplug the RCA from your LOC, and connect an iPod to those RCAs with a mini to RCA cable, does the noise go away? (Do NOT touch the amp gains for this test : )
 

·
Registered
Joined
·
35 Posts
Discussion Starter #19
I would have to check on the mp3-RCA adapter.

My system was a base-of-the-base systems that came in the car-driven directly off the deck.
 

·
Registered
Joined
·
329 Posts
How long are your RCA's?

Well, regardless I would lose the RCA's, move the LOC as close to your amp as possible and plug it directly into the amp using a couple of male to male adapters from Radio Shack.
 
1 - 20 of 27 Posts
Top