# Nothing I do gets rid of the alternator whine.



## PickleSlice (Apr 21, 2017)

I've searched and read plenty of threads on this, and I've tried quite a few things to mitigate the whine, but nothing has worked yet. I'm running out of ideas. 

The vehicle is a 2018 Nissan Frontier.

First thing, here is a diagram of my system as it sits now, everything is OFC including the 12ga speaker wire - 









I am running active from a MiniDSP 2x4 to a Sound Ordnance M25-4 amp. Previously (before I had the 2x4) there was a whine issue but I believed it to be resolved. I was able to get the grounds to where the whine would only be introduced just over half gain on the amp. Hiss and other noise started to get introduced at this level as well so I assumed it was a cheap amp doing what a cheap amp does. At this time I was running active from my head unit which was OK, but like everyone else, I wanted to tune with REW and have much more control, so I bought a MiniDSP 2x4.

Once I got everything installed and setup, 









I started up the truck and was immediately ear raped by the sound of a banshee. This **** was LOUD. I immediately turned off the truck and turned the gains all the way down, and started it back up. There is still very audible whine with the gains all the way down. 

This is how it sits now, I haven't used the system in the truck since Saturday, other than for testing purposes. 

Things I have tried so far:

--3 different RCA's. Current ones are double shielded expensive-ish. I've run them outside the install with the same result.

--Moving the amp ground to a thousand different places. I finally found a good ground on a bolt on the seat belt mount, NOT the seat belt bolt itself. This ground measures between .0 and .4 ohms









I have also moved the HU ground just as many times as the amp ground. I eventually settled on a ground that measures about .8-.9 ohms. Not ideal I know, but I quite literally cannot find a better ground than that. 

Now, with the grounds. There is something weird as **** going on with them. With the head unit ground, when I initially connected it, was reading less than an ohm. I measured it again the next day, and it was reading 19ohms! So that got me to thinking, that maybe even though this is a new-ish truck, maybe there is something weird with the chassis grounds. 

I go open the hood and see this ********, I did not see a grounding strap anywhere else so this appears to be the engine to chassis ground - 








WTF Nissan...

It was reading about 8ohms. I used some spare 8ga I had laying around and put it on there. The 8ga wire measured 0 - .1ohms before I added it. It now reads anywhere from 1 to 2 ohms connected. I did notice that it's grounded to a bracket...I think I will add the ground directly to the block and bolt the bracket over it to see if that may help.









Just for the hell of it, I added some 8ga from the battery to chassis but I don't believe it made much difference as it was reading well before adding the cable anyways. 

















Both locations were cleaned to bare metal which they weren't from the factory for some damn reason. This did dramatically cut down on the whine, but it is definitely still there and 100% unacceptable. I don't really want to do the Big 3 upgrade, once I'm finished I'll be 1500 watts total and the vehicle is still under warranty. I'd rather not take the chance on something like changing the electrical and voiding the warranty. If it becomes necessary, I'll try to install it all so that it is easily removable I guess.

-- I picked up a 3.5mm to stereo RCA cable and hooked up my phone. Pretty much 100% quiet. There's a little noise that starts to come in at around 75% to 80% gain, but I find that to be acceptable as even at 100% gain, you can just barely hear it. 

EDIT:
--I forgot to mention that I also did the old Pioneer PICO fuse grounding method with no change, as well as ran a ground to the chassis of the head unit. 

I've posted on quite a few forums and have gotten many suggestions which I will outline below, but I wanted to see what everyone here thinks. 

I picked up a ground loop isolator even though I really do not want to use one. I'd rather fix the issue and have the least amount of components in my system as possible, but it may turn out to be a necessity. I figured that since when I plugged my phone into the DSP directly there was virtually no noise from the amp, that it must be upstream of the amp, meaning the head unit. I wanted to see if the ground loop isolator will eliminate it. 
https://www.amazon.com/gp/product/B077Y5DLBB/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

--On Reddit.com/r/CarAV a user suggested I get one of these https://www.amazon.com/Behringer-HD...R6N248J5YBK6TZ88RB89&qid=1557317317&s=gateway and install it before one of these https://www.amazon.com/Install-Bay-...57134326&s=musical-instruments&sr=1-1-catcorr. I understand the concept of cleaning up the signal and then boosting the voltage back up, but adding additional components doesn't really entice me. I also wonder if just the Behringer HD400 by itself will work fine, as the MiniDSP is incapable of outputting more than .9v to the outputs anyway. 

--It has also been suggested that I ground everything to the same point in the cab. As you can see in my diagram, the head unit, and amp grounds are not connected. I can do this, but the ground would be about an additional three feet. I DID try to ground from the amp ground location to the HU ground location, but I do not think that is correct and it didn't help anyways. Maybe I need to bypass the current amp ground and go straight to the HU ground, but this is going to make my amp ground about 3 foot long. 

--Others have suggesting drilling through the floor pan and grounding directly to the frame, but come on, it's a new truck with less than 20k miles on it.

--Something like this has been suggested as well - https://www.amazon.com/Jensen-CI-2RR-IsoMax-Isolator-Jensen/dp/B00ASVWYCS which is very expensive and looks similar to the Behringer HD400 I posted earlier, but if it works without changing the audio signal at all, as I'm reading from looking into it, it might be worth the money.


Hopefully, someone has can point me in a direction that I haven't thought of yet.


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## t-roy (Jan 18, 2007)

I have used the Jensen Transformers. It is spendy but when all else fails it plain ass works worth every penny


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## PickleSlice (Apr 21, 2017)

t-roy said:


> I have used the Jensen Transformers. It is spendy but when all else fails it plain ass works worth every penny


I can't seem to find a cheaper alternative, so I may have to spend the money.

I'll have to get rid of the 2x4 and get something else like possibly the Dayton DSP-408 since I'm not going to buy two of those things to clean 4 channels.


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## PickleSlice (Apr 21, 2017)

I was also thinking that with the Behringer HD400, I can afford to get two, mount them under my amp rack, and run that AFTER the DSP and before the amp.

If I buy one, I'd have to run it before the DSP. 

https://www.amazon.com/gp/product/B000KUD2G4/ref=ask_ql_qh_dp_hza


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## mumbles (Jul 26, 2010)

I think the fact that you are getting different readings at the different ground points is a bad sign. If you want to try something on the cheap just as an experiment, get a really long (like 25 feet) piece of shielded wire... connect one end to your alternator, then move to your head unit, strip away about an inch of insulator and connect the bare section to your head units ground point. Repeat this same process for all the components in your signal path that have a ground point until you have chained everything to the same ground point. Since this is a test, it doesn't have to be pretty... you don't have to run the wire through the firewall, just out of the engine bay in through an open door to your head unit, back out the door to your trunk and so on (that's why you need a really long wire ).

Once you have everything at the same ground potential, the whine should stop. Then you would need to pick one solid ground location and ground everything to that spot. If the whine doesn't stop, you may have an issue with one of your components.


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## OldNewbie (Jan 12, 2019)

I would try grounding the HU at the amp's ground location first. You could also try lifting the RCA's ground at the amp


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## PickleSlice (Apr 21, 2017)

mumbles said:


> I think the fact that you are getting different readings at the different ground points is a bad sign. If you want to try something on the cheap just as an experiment, get a really long (like 25 feet) piece of shielded wire... connect one end to your alternator, then move to your head unit, strip away about an inch of insulator and connect the bare section to your head units ground point. Repeat this same process for all the components in your signal path that have a ground point until you have chained everything to the same ground point. Since this is a test, it doesn't have to be pretty... you don't have to run the wire through the firewall, just out of the engine bay in through an open door to your head unit, back out the door to your trunk and so on (that's why you need a really long wire ).
> 
> Once you have everything at the same ground potential, the whine should stop. Then you would need to pick one solid ground location and ground everything to that spot. If the whine doesn't stop, you may have an issue with one of your components.



When you say to connect it to the alternator, you mean like the chassis correct?


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## Mahapederdon (Aug 19, 2016)

Run power and ground from the battery to both the Amps and deck. Make sure the battery has good ground to chassis and good positive to alternator. Also make sure engine is grounded to chassis. Alternator whine is the worst. Good luck.


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## MrGreen83 (Jun 11, 2015)

Tried swapping out DSP? 


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## haromaster87 (Jan 20, 2012)

Hate to add another possibility and I doubt this would be an issue since it's such a new truck, but is the noise possibly related to ignition components instead of the alternator?

I'm fighting an issue very similar to yours, but mine is in an 80's Mustang with a far different ignition layout than anything new. But still, I chased every alternator related possibility before realizing the alternator wasn't causing the noise.

I ended up removing the serpentine belt and turning the car on(just for a minute) and even with the alternator both disconnected from the electrical and not spinning, my noise persisted.

My head unit picks up the majority of the noise and sends it to the amps and everything else connected. When I'd plug my phone directly to the amp with a cable, no noise. Like I said, doesn't seem likely on such a new truck, but just something else to consider if you run out of ideas on Alternator noise causes


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## EmptyKim (Jun 17, 2010)

MrGreen83 said:


> Tried swapping out DSP?
> 
> 
> Sent from my iPhone using Tapatalk


On a similar theme, maybe try process of elimination to find out what is causing the noise.

*DSP *- You could run the RCA's straight from the deck to AMP to see if your DSP is the culprit. Make sure to set high pass filter on your tweeters.

*Headunit *- Run 3.5mm jack from music source like phone or iPod to miniDSP


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## mumbles (Jul 26, 2010)

PickleSlice said:


> When you say to connect it to the alternator, you mean like the chassis correct?


Yes, to the case of the alternator.


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## Hillbilly SQ (Jan 26, 2007)

Since you already said the headunit ground was iffy I'd run a 14 or 12g ground from headunit to the amp ground location and see what happens. You can keep the existing power connection for the headunit if you want. If that doesn't work do process of elimination. You said the noise went away when you plugged directly into the processor correct? If so that means you just ruled out everything from the processor down. This means you either have...

HEADUNIT GROUND TOO DIFFERENT FROM WHERE EVERYTHING ELSE IS GROUNDED

RCA CABLES PICKING UP NOISE SOMEWHERE ALONG THE LINE. WHAT KIND OF RCA'S ARE YOU USING?

OR BOTH


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## PickleSlice (Apr 21, 2017)

MrGreen83 said:


> Tried swapping out DSP?
> 
> 
> Sent from my iPhone using Tapatalk





EmptyKim said:


> On a similar theme, maybe try process of elimination to find out what is causing the noise.
> 
> *DSP *- You could run the RCA's straight from the deck to AMP to see if your DSP is the culprit. Make sure to set high pass filter on your tweeters.
> 
> *Headunit *- Run 3.5mm jack from music source like phone or iPod to miniDSP


I haven't swapped out the DSP because when I went directly to it from my phone, it was crystal clear. I can definitely still pull it, but that makes me feel like it's before the DSP. I've also used another pair of RCA's and ran them directly from the HU to the DSP/AMP with that same issue.



Hillbilly SQ said:


> Since you already said the headunit ground was iffy I'd run a 14 or 12g ground from headunit to the amp ground location and see what happens. You can keep the existing power connection for the headunit if you want. If that doesn't work do process of elimination. You said the noise went away when you plugged directly into the processor correct? If so that means you just ruled out everything from the processor down. This means you either have...
> 
> HEADUNIT GROUND TOO DIFFERENT FROM WHERE EVERYTHING ELSE IS GROUNDED
> 
> ...


I plan to give that a shot tonight, grounding to the same spot. 

I am using shielded RCA's, these in particular, but I've tried three different kinds with the same results.


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## Hillbilly SQ (Jan 26, 2007)

My gut feeling is saying headunit ground. I've done the dance with alty whine many times and it's no fun.


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## PickleSlice (Apr 21, 2017)

Hillbilly SQ said:


> My gut feeling is saying headunit ground. I've done the dance with alty whine many times and it's no fun.


It's gonna be a long ground, but if it works, I'll take it.


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## Hillbilly SQ (Jan 26, 2007)

PickleSlice said:


> It's gonna be a long ground, but if it works, I'll take it.


The shortest distance isn't always the best path to take


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## kenny5555 (Jan 17, 2008)

One of the old time methods was to use another battery like a motorcycle battery and power each component with that 12volts. That isolates each component and verifies which component is inserting the whine. Once that is done you can concentrate on that component. Then get an isolated power supply for that component or lift its audio shield.


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## Adrock (Jan 21, 2019)

If I am reading your post right, you hooked up a 3.5mm jack to RCA and used your phone as a source with minimal to no noise? Was this hooked up to run through the DSP into the amp, or straight to the amp? If this is the case, then through the process of elimination it would almost be safe to say it's an issue with the source unit.

The question then goes back to the headunit install? Who intalled it?

There is actually another ground on that JVC. The e-brake circuit completes a ground as well. Most people don't want to deal with the e-brake, so they ground right to the chassis of the headunit itself. Could this also be a cause?

There also appears to be 4 - 3.5mm jack's on the back of the headunit. Is everything hooked up correctly. We're all unused wires properly capped? Were any unused composite video Jack's capped? Is the harness wired 100% correct? 

If the amp and DSP are silent with a different source, then you grounds sound like they're ok. It sounds like the headunit is the root cause if I'm understanding you correctly.


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## PickleSlice (Apr 21, 2017)

Hillbilly SQ said:


> The shortest distance isn't always the best path to take





Adrock said:


> If I am reading your post right, you hooked up a 3.5mm jack to RCA and used your phone as a source with minimal to no noise? Was this hooked up to run through the DSP into the amp, or straight to the amp? If this is the case, then through the process of elimination it would almost be safe to say it's an issue with the source unit.
> 
> The question then goes back to the headunit install? Who intalled it?
> 
> ...


Well I just pulled the headunit out real quick (nothing is bolted/screwed into my truck right now because I've been working on it every goddamned night) and ran 10g wire from the headunit to the amp ground and it did improve very very much. I did notice something odd though. After I connected the wire to the amp ground, I tested the ohms of the wire. Through 13 feet of wire from the bolt to the end of the roll, it measured .0 -.3ohms. I was understandably excited, but as soon as I made the connection, I tested from the radio harness to the ground and it was reading anywhere from 5 to 6 ohms.

I left the radio on when I disconnected the new ground and it stayed on, but got noticeably noisy. Thinking that was odd, I disconnected the antenna wire because I had a similar issue with a past vehicle grounding through the antenna. It did not turn off when I disconnected the antenna.

My son chose this time to come out want to play and not wanting to miss out, I left it there.

I betcha when I go back out there and pull the RCA's, it'll shutoff.

I'll update when I try it. 


EDIT: 

Adrock, everything you said is correct. I also grounded my parking brake to the harness. 
Edit 2: I installed everything, made all the harnesses and custom made the camera harness since there isn't one available. I have tested the noise with all of that disconnected and just the power. 

I'm considering buying another oem harness and another harness for the JVC and only wire up the power and ground and see how that goes. 

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## PickleSlice (Apr 21, 2017)

Alright, new information.

I go back out, undo the new ground. Headunit stays on.

Undo the rcas, head unit stays on.

Undo the antenna, head unit stays on.

Unplug the camera harness, head unit shuts off. I remove the harness plug it all back in.

Undo the main ground, rcas, the antenna, the head unit stays on.

I undo the iDataLink cable from the maestro rr, and head unit shuts off.

I reconnect the main ground, reconnect the idatalink cable, turn on the unit.

I undo the main ground, head unit stays on and wailing. Whine and static is there.

I combined all of the harnesses into one using Tessa tape.

It combines the idatalink maestro harness, the camera harness (which has a 12v to 6v step down in it) and the vehicle harness all in one.


I think my next step is, I'm going to buy a new oem adapter harness and a new jvc harness, and only connect power, ground and remote and see what happens. Then if it's good, I'll start adding in the other items.

Opinions; Should I make sure all grounds from all the accessories share the same ground with the head unit, or should I keep the head unit on a separate ground from everything else. I think they should all be on the same ground, but I wanted to ask those of you who are smarter than I am.









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## Adrock (Jan 21, 2019)

I don't know brother. I'd take off the tesa tape and check everything again. It sounds like it's your harness. There is no reason to not run that idata unit on the same ground as the headunit. That's how they diagram the installation. 

How are your connections made? Solder? Did you heat shrink each joint? How did you cap each unused wire? I personally de-pin anything and everything that I don't use on the harnesses. I also just crimp a ring terminal on the e-brake wire, undo one of the screws on the headunit chassis and then attach the wire. No need for the e-brake ever again. 

Just out of curiosity, did you try setting the e-brake to see if that helps the whine? 

Another way to check that harness without taking it apart is to follow the diagram and use your multimeter to test each pin? Meter your ground pin on the headunit harness and then go through each and every pin on all connections to see if you have a ground that doesn't belong. And verify that each wire has the correct connections using continuity. You never know if something just wasnt hooked up correctly. It happens to everyone because no one is perfect all the time.


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## PickleSlice (Apr 21, 2017)

Adrock said:


> I don't know brother. I'd take off the tesa tape and check everything again. It sounds like it's your harness. There is no reason to not run that idata unit on the same ground as the headunit. That's how they diagram the installation.
> 
> How are your connections made? Solder? Did you heat shrink each joint? How did you cap each unused wire? I personally de-pin anything and everything that I don't use on the harnesses. I also just crimp a ring terminal on the e-brake wire, undo one of the screws on the headunit chassis and then attach the wire. No need for the e-brake ever again.
> 
> ...


I set the ebrake everytime I park it, so it's probably always on. I've never paid attention since it's an unconscious habit. I'll make note of that next time.

I ordered a new JVC harness and a new oem adapter harness, $40 later, they'll be here tomorrow.

I plan to connect it with the bare minimum. If it still whines, I'm going to remove the headunit from the mount and try it again.

I plan to do that last part because in my hours of research, I've found out that Nissan grounds the factory radio through the mount and/or the antenna. The antenna is disconnected so all that leaves is the frame if it still whines with only the rca's and power/remote/ground connected. 

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## OldNewbie (Jan 12, 2019)

> Opinions; Should I make sure all grounds from all the accessories share the same ground with the headunit, or should I keep the headunit on a seperate ground from everything else.


.
My answer is Yes, connect all needed grounds to the 10 AWG wire from the amp's ground. Leave off any unneeded grounds that can be eliminated. 
Good luck!


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## Holmz (Jul 12, 2017)

Many ^have said^ similar...

The fact that you said an iPhone plugged into the amp was fine means that the noise is coming into the amp.
I would plug head phone into the rcas from the HU.

If the noise has gone away, then the noise from a different ground at the amp than at the HU, or coming into the RCAs.

If the noise is there then at least you have more ideas to pursue.


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## PickleSlice (Apr 21, 2017)

Holmz said:


> Many ^have said^ similar...
> 
> The fact that you said an iPhone plugged into the amp was fine means that the noise is coming into the amp.
> *I would plug head phone into the rcas from the HU.*
> ...


I just purchased this, it will be here tomorrow. I hadn't thought about this yet, thank you for the advice.



Another thing I noticed, I don't believe I've ever checked the amp ground with the truck running, but I did last night and it was like 30 to 40ohms. Is this normal? The amp ground tests at almost 0ohms when it's not running.


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## gijoe (Mar 25, 2008)

I have a difficult time trusting your ground measurements. The resistance that you're claiming at times doesn't make sense. A good ground should barely register a reading, I wouldn't even use a ground measuring 0.5 ohms. I didn't read every post here, but at a quick glance I'm suspicious of your measuring tools, or technique.


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## PickleSlice (Apr 21, 2017)

gijoe said:


> I have a difficult time trusting your ground measurements. The resistance that you're claiming at times doesn't make sense. A good ground should barely register a reading, I wouldn't even use a ground measuring 0.5 ohms. I didn't read every post here, but at a quick glance I'm suspicious of your measuring tools, or technique.


I thought the same thing and picked up another DMM for that reason. 

My method is I always test the wire by itself. Then I'll connect it and then measure it's contact points on both ends. 

If there's a better method I'd love to hear it.


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## OldNewbie (Jan 12, 2019)

I have to be careful to read my auto-ranging DMM correctly. Some times 0.008 looks like 0.8 Its display is not great but has a bluetooth connection to my phone which is much easier to read.


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## Adrock (Jan 21, 2019)

Don't forget to test the resistance of your test leads. This should be subtracted from whatever reading your taking.


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## mumbles (Jul 26, 2010)

I wish I'd known that your head unit wasn't permanently attached in your dash...

Anyway, you might try moving the head unit to the trunk and connecting it to the same ground and power as the amp. Disconnect everything upstream of the amp, the DSP's etc... and run your RCA's from the head unit directly to your amp... you'll lose factory integration, but at this point we just want to see if you can get a noise-free signal to the speakers. Then power things up and listen for the whine. You have essentially done this before when you connected the head unit and amp ground together, but this time you're taking everything else out of the equation.


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## PickleSlice (Apr 21, 2017)

OldNewbie said:


> I have to be careful to read my auto-ranging DMM correctly. Some times 0.008 looks like 0.8 Its display is not great but has a bluetooth connection to my phone which is much easier to read.


I have it set to measure 200 ohms.



Adrock said:


> Don't forget to test the resistance of your test leads. This should be subtracted from whatever reading your taking.


Yessir, I do every time. They always read about .3 ohms.



mumbles said:


> I wish I'd known that your head unit wasn't permanently attached in your dash...
> 
> Anyway, you might try moving the head unit to the trunk and connecting it to the same ground and power as the amp. Disconnect everything upstream of the amp, the DSP's etc... and run your RCA's from the head unit directly to your amp... you'll lose factory integration, but at this point we just want to see if you can get a noise-free signal to the speakers. Then power things up and listen for the whine. You have essentially done this before when you connected the head unit and amp ground together, but this time you're taking everything else out of the equation.


Oh no, it's installed. I just meant that it's just snapped in right now, and I haven't screwed in the trim pieces because I've been working on this nightly trying to resolve it.


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## PickleSlice (Apr 21, 2017)

Alright so this came in today, and it appears to have removed the whine.








I could just barely hear it at max gain, but I would never have it that loud because of the hiss from my amp anyways. This has happened before where the whine would be gone for a bit but something would change and right back it comes. I'll just have to drive it and see. 

This obviously makes me incredibly happy that I can at least enjoy the system as it sits, but knowing that it's not actually "fixed" will bother me.

The new harnesses will be here tomorrow. I'm definitely going to wire them up and test with them.

Part of me wants to say whatever and move on since I've had a brand new UMIK-1 mic for over a month and haven't used it. I want to start doing the fun stuff, like learning rew and tuning. 

The other part of me who prides himself on doing things right wants to fix the source issue.

I'll wait until those harnesses are in before I decide I think. I feel like if I connect the headunit up with the bare minimums and it still whines, I'm just gonna say screw it and move on. Guess we'll see. 

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## PickleSlice (Apr 21, 2017)

What effect do these noise suppressors have on the audio signal? I know my headunit does over 4.6v from the preouts, I'll test tonight and see what it measures.

I've searched and looked and have conflicting reports. Some say they are horrible, but I've seen the infamous Andy here on DIYMA say they definitely aren't bad if applied correctly.



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## Mahapederdon (Aug 19, 2016)

PickleSlice said:


> What effect do these noise suppressors have on the audio signal? I know my headunit does over 4.6v from the preouts, I'll test tonight and see what it measures.
> 
> I've searched and looked and have conflicting reports. Some say they are horrible, but I've seen the infamous Andy here on DIYMA say they definitely aren't bad if applied correctly.
> 
> ...




Most of those are just transformers so they isolate the ground. So the ground on one end is not the ground on the other. 

I'm not sure about loss. I'm sure there is something but I don't know if it's allot. I'm like you. I'd take the win but still find the real problem.


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## PickleSlice (Apr 21, 2017)

Mahapederdon said:


> Most of those are just transformers so they isolate the ground. So the ground on one end is not the ground on the other.
> 
> I'm not sure about loss. I'm sure there is something but I don't know if it's allot. I'm like you. I'd take the win but still find the real problem.


I just went went out and found out the loss. It's very minimal.

Before isolator, at the end of 6 ft rca -









After isolator, at the end of 6ft rca -









What is that, .25 of a volt? Seems acceptable to me, especially since I'm still above my headunit rated 4v out.

I'm the perfectionist type, installing this little setup I have now took waaaay longer than it should've, but I think I'm done chasing this goddamned ground loop. I just went out for about a 45 minute drive and it's the first time I've truly enjoyed my system since I've installed it.

I took everything up to clipping point and there is zero noise.

Unless anyone has a good reason for me to continue, I think it's time for me to move on. I've had this truck apart almost every single night for over a month. I've stripped two of the seat mount bolt holes, so I have to helicoil those and I've scratched a few of my trim pieces. This is a brand new truck, my wife thinks I'm crazy. 

I'm not happy with the volume output (now that I can turn it up without wanting to kill myself) so I may get rid of the MiniDSP 2x4 since it's only .9v out plus I'm going to need another 2x4 once I get my subs installed plus another plug in. Even if I don't need to buy another power supply that puts me at an additional $115 plus shipping. I feel like a Dayton DSP-408 is a better match with the number of outputs and the 4v out that it has.

That's a topic for another thread though. 

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## Mahapederdon (Aug 19, 2016)

Check it at like 18khz and at 40hz. I think they may roll off and that's the downfall. But if your my age it's not gonna matter.


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## PickleSlice (Apr 21, 2017)

Mahapederdon said:


> Check it at like 18khz and at 40hz. I think they may roll off and that's the downfall. But if your my age it's not gonna matter.


I've read about this but I'm still learning, how would I test the roll off? Using my mic and measuring? 

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## Mahapederdon (Aug 19, 2016)

PickleSlice said:


> Mahapederdon said:
> 
> 
> > Check it at like 18khz and at 40hz. I think they may roll off and that's the downfall. But if your my age it's not gonna matter.
> ...


Just do what you did with the scope but use higher and lower sine waves. Like run 18khz and test the output vs the input.

Edit. That scope looks pretty sweet. I have one of the cheaper handhelds.


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## Holmz (Jul 12, 2017)

PickleSlice said:


> ...
> 
> 
> Another thing I noticed, I don't believe I've ever checked the amp ground with the truck running, but I did last night and it was like 30 to 40ohms. Is this normal? The amp ground tests at almost 0ohms when it's not running.


I think 0 ohms is what you want.


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## PickleSlice (Apr 21, 2017)

Mahapederdon said:


> Just do what you did with the scope but use higher and lower sine waves. Like run 18khz and test the output vs the input.
> 
> Edit. That scope looks pretty sweet. I have one of the cheaper handhelds.


I'll do that, thank you.

It was only $40! To think, I almost bought Fluke.
ETEPON Digital Oscilloscope Kit with BNC-Clip Cable Probe Power Adapter (Assembled Finished Machine) EM001 (Black) https://www.amazon.com/dp/B07QDYFMM3/ref=cm_sw_r_cp_apa_i_odv1Cb7QZD155


Holmz said:


> I think 0 ohms is what you want.


Then uh oh... Something definitely isn't right. I'll see about getting a video showing the change when it's running. 

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## Holmz (Jul 12, 2017)

Put a jumper cable on the ground to the battery when you do the video and see if the numbers change.


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## PickleSlice (Apr 21, 2017)

Holmz said:


> Put a jumper cable on the ground to the battery when you do the video and see if the numbers change.


I tried but my cables are too rusted, lol.

I did just get 10 feet of ofc 4ga in though, I can do it with that. 

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## Holmz (Jul 12, 2017)

PickleSlice said:


> I tried but my cables are too rusted, lol.
> 
> I did just get 10 feet of ofc 4ga in though, I can do it with that.


How can copper and brass jumper cables rust?

I think your ground measurements were probably good... there is about zero ohms in the DMM cables and in the ground wire with no current flowing.

As soon as current start flowing then there is a voltage drop, so if the amp ground was as scrawny as the earlier engine to chassis wire, then make those ground straps (much) bigger.

On the other hand that transformer essentially makes the RCAs look more like a differential input.
So they SHOULD cure any ground loop related issue.

I would probably still fix the grounds, but it is hard to make a cogent argument that something that is working, needs to be fixed... you won't likely hear any 40kHz roll off, with a 22kHz (bandwidth limited) CD.

Basically... now that it is working... leave it alone.
The only reason to change anything now would be academic and learning, but not for pragmatic "better sound".

When it come to wine, a good Aussie Shiraz, a Cab Franc, or a Cab Sav beats alternator whine 99% of the time.


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## PickleSlice (Apr 21, 2017)

The clamps on the cables have surface rust, I need to clean them up.

I'm leaning towards your last point though... Just enjoy it.

I may build out the rest of my system and then circle back around to the whine. 

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## PickleSlice (Apr 21, 2017)

I'm getting rid of the MiniDSP 2x4 and I have a Dayton DSP-408 on the way.

So tonight I went active from the headunit to the amp. I like to setup gain firstly by oscilloscope using -5db tones to establish a baseline and then I adjust by ear.

The whine was there.

I finished setting it up anyways, turned off the truck and went inside. Came back out shortly after to go for a drive, and the whine was gone..

I have no idea what to make of that. 


:edit:

It just occurred to me that I did install the camera harness that I made. I'll need to pull that out again for a few days to see if that is it. 

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## HereticHulk (Nov 8, 2009)

My whine just started with the addition of a new amp. Went from a Q600.1- Image Dynamics 1-Channel 600 Watt Amplifier to a Punch P1000-1bd. Nothing else has changed. Grounds are all the same. In fact I shortened the grounds to the amps as much as possible thinking this would be a good place to start. Both amp grounds are less then 18" in length and grounded to the same place.


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## Xtremevol (Apr 21, 2020)

Hate to bring back an old thread, but did you ever come up with a solution? I am fighting this same noise on a 2019 Frontier.


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## dumdum (Feb 27, 2007)

delete me, old thread, didn’t notice


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## dumdum (Feb 27, 2007)

delete me


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