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feeshta 05-28-2019 04:50 PM

Best methods for dealing with alternator whine?
 
Hello all. Dealing with a little bit of an alternator whine issue on my 2007 Porsche Cayman. I'm running a Sony xav-ax5000 head unit rca out to a Zapco DSP Z8 which feeds a JL Audio XD800/8. I'm getting a persistent alternator whine due most likely to the fact that the RCAs between head unit and DSP must pass very close to the main charging cable for the battery. I've upgraded the RCA cables to shielded ones, checked grounds, reduced amplifier gain as much as possible, etc, but it's not cooperating so far.

Any ideas on how to best deal with this? A balanced line driver crossed my mind, but I don't know what options are out there these days.

gijoe 05-28-2019 04:53 PM

Re: Best methods for dealing with alternator whine?
 
In my experience, routing RCAs close to power wires rarely causes noise. I'd take a closer look at your grounds. You have a DSP, an amp, and a head unit, are they all grounded to the same spot, or different spots?

OldNewbie 05-28-2019 06:48 PM

Re: Best methods for dealing with alternator whine?
 
I agree with gijoe. These issues are normally groud related. Have you tried rerouting the RCAs or the power on a temp basis to confirm the noise is due to due proximity?

Truthunter 05-28-2019 07:07 PM

Re: Best methods for dealing with alternator whine?
 
Have you unplugged the RCAs from the DSP inputs to see if the noise persists?

Sine Swept 05-28-2019 07:49 PM

Re: Best methods for dealing with alternator whine?
 
Tying in all your grounds to one common location will reduce the chance of difference in voltage potential which is generally the cause of noise.

Also try noise in these scenarios 1) ACC 2) Key Forward Car OFF 3) Car running

Some car's can produce noise at 2).

Other sources of noise can be dealing with balanced / unbalanced systems.

feeshta 05-28-2019 11:28 PM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by gijoe (Post 5706399)
In my experience, routing RCAs close to power wires rarely causes noise. I'd take a closer look at your grounds. You have a DSP, an amp, and a head unit, are they all grounded to the same spot, or different spots?

I started from a presumption that it was ground related as well, but have not had success pursuing that option. Currently amp and DSP are grounded together, with head unit grounded to factory wire. I did try bringing ground from the amp/dsp point to the head unit with no success, didn't bother routing wire through dash after that as it is a pain in the ass due to the car's size and low stance. Ohmmeter shows near 0 resistance between the two ground points, but that obviously isn't completely reliable.

Quote:

Originally Posted by OldNewbie (Post 5706453)
I agree with gijoe. These issues are normally ground related. Have you tried rerouting the RCAs or the power on a temp basis to confirm the noise is due to due proximity?

I did run a long RCA out and around, and whine levels varied depending on how close you got to the battery area. Never could completely eliminate them though that method, which I attributed to the fact that my extra long RCAs were completely unshielded cheapo home variety that I had sitting around and not quite long enough to go completely out and around.

Quote:

Originally Posted by Truthunter (Post 5706459)
Have you unplugged the RCAs from the DSP inputs to see if the noise persists?

Noise is eliminated if you unplug source RCAs from the DSP inputs.

I should also note that originally the system used a Nexus 7 tablet as a source with a USB to Optical DAC that fed the DSP via Toslink cable. Never had any noise issues with that setup at all. Only surfaced when I switched to the Sony. Had backup cam and charging issues with the Nexus, so I ditched it.

SkizeR 05-28-2019 11:34 PM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by feeshta (Post 5706541)
Noise is eliminated if you unplug source RCAs from the DSP inputs.

This tells me that you should try grounding the head unit to where the amps/dsp are grounded. You mentioned you tried similar though? It was worded in a way that is hard to follow if you did exactly what i suggested or something different.

feeshta 05-29-2019 11:03 AM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by SkizeR (Post 5706543)
This tells me that you should try grounding the head unit to where the amps/dsp are grounded. You mentioned you tried similar though? It was worded in a way that is hard to follow if you did exactly what i suggested or something different.

I used a length of 12 Gauge wire, roughly equal to factory head unit ground dimensions, and went from head unit to the negative battery terminal, where the amplifier and DSP were already grounded. As getting through the firewall is a pain in the ass due to the small dimesnions of the footwell in the car, I simply went out the door and around as a test of theory before doing the work. This did not yield any change in behavior, so I did not bother with running a new wire from headunit to battery negative terminal.

tranv9565 05-29-2019 11:36 AM

Re: Best methods for dealing with alternator whine?
 
Probably not the best method and I know people are going to hate me for this but look into a ground loop isolator.

Specifically a Jensen CI-2RR Iso-Max. It's expensive but after months of troubleshooting my alt. whine issue, I said to hell with it and purchased the Jensen Transformer.

Never looked back since.

You can purchase through Part Express. If it doesn't work, I know they have an excellent return policy.

https://www.parts-express.com/jensen...xoCm_cQAvD_BwE

Zardnok 05-29-2019 12:12 PM

Re: Best methods for dealing with alternator whine?
 
Back in the day we used to ground the outer RCA sleeve to the back of the radio itself. Just take a short piece of black primary wire, put a ring terminal on the end and screw it to the backstrap hole on the back of the radio. Then strip the other end and trim back a few of the wires and bend it over. Loop that over the outside of the RCA sleeve and reconnect it. If that doesn't help, try to do the same thing on the other end, short piece of primary wire, ground it to the amp ground, and bend over the other end around the outer RCA sleeve. If that doesn't work, disconnect ground up front and try it with just rear RCA outer grounded.

Also anywhere your RCA crosses a power wire, if possible do it at a right angle to minimize the noise.

Sine Swept 05-29-2019 01:51 PM

Re: Best methods for dealing with alternator whine?
 
If your system is running 100 amps or more you should consider running a dedicated ground from body ground at battery to rear block to feed amps / dsp.

Is radio still grounded through factory ground wire?

feeshta 05-30-2019 01:34 PM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by Zardnok (Post 5706745)
Back in the day we used to ground the outer RCA sleeve to the back of the radio itself. Just take a short piece of black primary wire, put a ring terminal on the end and screw it to the backstrap hole on the back of the radio. Then strip the other end and trim back a few of the wires and bend it over. Loop that over the outside of the RCA sleeve and reconnect it. If that doesn't help, try to do the same thing on the other end, short piece of primary wire, ground it to the amp ground, and bend over the other end around the outer RCA sleeve. If that doesn't work, disconnect ground up front and try it with just rear RCA outer grounded.

Also anywhere your RCA crosses a power wire, if possible do it at a right angle to minimize the noise.

They used to actually make RCA wires with an integrated ground for this purpose, but I haven't seen them in my search so far. I do have the RCA crossing the path of the positive lead at a right angle, and as far away as is physically possible in the confined area, which would be about 4 inches.


Quote:

Originally Posted by Sine Swept (Post 5706787)
If your system is running 100 amps or more you should consider running a dedicated ground from body ground at battery to rear block to feed amps / dsp.

Is radio still grounded through factory ground wire?

There is already a dedicated ground. The amp sits less than 2 feet from the battery, so it is grounded directly to the negative Battery Terminal with 4 guage wire. The JL uses an 80 Watt fuse anyway. The Head unit is still grounded to the factory ground at the moment, but as mentioned above, running a dedicated ground did not affect the noise.

Holmz 05-30-2019 03:35 PM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by gijoe (Post 5706399)
In my experience, routing RCAs close to power wires rarely causes noise. I'd take a closer look at your grounds. You have a DSP, an amp, and a head unit, are they all grounded to the same spot, or different spots?

Your experience is understandable...

The reason is that most of the power wires are carrying steady current.
And the magnetic field is not changing.

If you run them beside a CAN buss, or some lines where there is alternating current (or some pulsed current draw), then the magnetic felid will be changing and the RCAs will act like 1/2 of a transformer shielded or not.

gijoe 05-30-2019 03:53 PM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by Holmz (Post 5707201)
Your experience is understandable...

The reason is that most of the power wires are carrying steady current.
And the magnetic field is not changing.

If you run them beside a CAN buss, or some lines where there is alternating current (or some pulsed current draw), then the magnetic felid will be changing and the RCAs will act like 1/2 of a transformer shielded or not.

Right. Running them close to something like a fuel pump can cause some trouble, but I've never had an issue with noise from power wires.

Theslaking 05-30-2019 08:50 PM

Re: Best methods for dealing with alternator whine?
 
Try powering your head unit with a different power source/wire. Unplug your factory antenna. Sometimes the factory HU grounds through the antenna and can cause problems with aftermarket radio's.

Sine Swept 05-30-2019 11:39 PM

Re: Best methods for dealing with alternator whine?
 
I like this train of thought. If your factory ground is not that great your antenna ground becomes the path of least resistance.

Also consider this, if you were to try a ground loop isolator, you actually have 2 sources of input for turning on your radio, your constant power and your accessory power. As a test I would actually twist power / acc and hook up to to GLI and see for hell of it if it makes a difference. If it was enough to deter your whine then I would try 2 GLI's, one on power, one on constant.

Sine Swept 05-30-2019 11:49 PM

Re: Best methods for dealing with alternator whine?
 
http://www.pvv.org/~syljua/merc/TooSeptST07.pdf

This article goes into finding AC ripple coming from your alternator

Holmz 05-31-2019 03:38 AM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by gijoe (Post 5707219)
Right. Running them close to something like a fuel pump can cause some trouble, but I've never had an issue with noise from power wires.

That fuel pump example would need a lot of pulsing current.

However you've nailed it with the grounds... most ground loop problems have a problems with multiple grounds, and big open loops.
(Fixing the alternator, does not fix the ground loop.)

robspeed325i 05-31-2019 03:46 PM

Re: Best methods for dealing with alternator whine?
 
I had great results with a $12 noise filter (PAC CSS-12).

https://amzn.to/2MmgKDc

XSVTOYZ 06-01-2019 12:40 PM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by robspeed325i (Post 5707573)
I had great results with a $12 noise filter (PAC CSS-12).

https://amzn.to/2MmgKDc

I have used something like this before with success as well,
seems like grounds should have resolved it but in the end this for the head unit, was nice to have that noise gone

Sine Swept 06-01-2019 08:34 PM

Re: Best methods for dealing with alternator whine?
 
I just re-read this again and noticed you are grounded directly to the battery. I would remove from battery post and ground amp to body ground at battery.

If you were to remove the body ground while leaving your amp hooked up like that your car will effectively ground through your amplifier.

It may not cause you issues per say, but it is good practice.

GEM592 06-02-2019 06:44 AM

Re: Best methods for dealing with alternator whine?
 
Quote:

Originally Posted by feeshta (Post 5706395)
Hello all. Dealing with a little bit of an alternator whine issue on my 2007 Porsche Cayman. I'm running a Sony xav-ax5000 head unit rca out to a Zapco DSP Z8 which feeds a JL Audio XD800/8. I'm getting a persistent alternator whine due most likely to the fact that the RCAs between head unit and DSP must pass very close to the main charging cable for the battery. I've upgraded the RCA cables to shielded ones, checked grounds, reduced amplifier gain as much as possible, etc, but it's not cooperating so far.

Any ideas on how to best deal with this? A balanced line driver crossed my mind, but I don't know what options are out there these days.

I assume the power wiring/charging system is correct and decent.

Then I would start by removing the deck from the signal path and checking for improvement. Unhook the deck and drive the DSP with and ipod or something. If there is improvement, look into better deck grounds or the RCA shielding trick (which very often helps, especially with Pioneer decks for example.)

If no improvement, eliminate the DSP also and try driving each amp with an ipod to try and further isolate the problem.

During these tests, you may want to use minimal or at least nominal gain settings

K-pop sucks 06-04-2019 09:55 PM

Try changing rca cables and make sure they are correctly seated on the amp/headunit.

dumdum 06-05-2019 01:31 AM

Re: Best methods for dealing with alternator whine?
 
Are any of the items of equipment screwed to the metal body of the vehicle? As Iíve known that cause ground loops in rare cases, Iíve yet to experience a whine or hum I couldnít sort in one way or another through swapping parts/earth locations/fixing points


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