How to kill engine noise?

[wuemura]

Hello guys!

After building the Surround sound for car and installed in my car i've noticed that there is a engine noise on the speakers, the noise increase decrease when i hit the throttle, i can hear the noise when the volume is down and the ambient is quiet other wise there is no noise, removing the circuit makes the noise go away.

The first photo is the prototype board, and the second is the modifications that i've done over the original schematic.

Thank you.

View attachment 39571

View attachment 39572

 

[audioguru2]

Hi Wellington,
Describe the noise. Is it alternator whine? It changes its pitch with the revs of the engine. The choke coil and filter capacitor should stop it.
Maybe you have a ground loop.
I bet the 12V zener diode is burnt out. Cars have batteries that charge at up to 14.4V. Anything more than 12V will smoke the 12V zener.

 

[wuemura]

By the way, the effect is AMAZING. If you are doing nothing and are searching for something to build, this is the one, incredible!!!! I'm using the Alpine SBS-05DC to make my center channel but with out it it will do the same effect.

Here is some examples, but, hearing the effect is much better.

Gnarls Barkley - Crazy
You can hear the "uuuhhhhh" at the back of your car and the main voice in front speakers.
http://www.electronics-lab.com/forum/index.php?action=pm
7 messages
Cherish ft. Sean Paul Of The YoungBloodZ - Do It To It
You can hear the "Hey, hey, hey" and others back vocals at the back, the sound (voice )goes front/back make an amazing ambient.

JOAN OSBOURNE - One Of Us
Guitar in front, drums at back, than the guitar goes to back and the main vocals go to front.

Black Eyed Peas - Pump It
The "ha, ha, haaaa" is very clear at the back, and main vocals at the front.

Shows - ANY
If you take an Elvis Presley live recorded Show, you can hear things that wasn't there before, like people talking at the back, people chating, walking, screaming and so on, making an incredible ambient! And oh yes, looks like you are in the middle of the show, Elvis vocals in front, back vocals, crowd and everything else at the back of your car.

A MUST HAVE in your car!

 

[wuemura]

Hi Wellington,
Describe the noise. Is it alternator whine? It changes its pitch with the revs of the engine. The choke coil and filter capacitor should stop it.
Maybe you have a ground loop.
I bet the 12V zener diode is burnt out. Cars have batteries that charge at up to 14.4V. Anything more than 12V will smoke the 12V zener.

It changes its pitch with the revs of the engine, it should stop it but it still there.
No, the zenner is fine, my car battery charges at 13.8v max, the zener never heat it up. I will make some more tests tomorrow and i will let you know.

 

[wuemura]

I can't believe it, the guy who installed the device on my car was feeding the circuit with 12v from ignition (also know as REMOTE) not directly from the battery > In my car was made a specific design to distribute the voltage directly from battery to amps and head unit. The voltage from the battery goes to a distribution box, than to a filter responsable to kill any noise from the alternator, from there it goes to amps and head unit.

The guy design the thing and the same guy screw up, does any body has a shotgun around? ;D

Now the device is installed again with my supervision, looks like the noise is gone, but i will have to test it at night.

Thanks again audioguru.

 

[nyjumpee]

Test it at night?

 

[wuemura]

Hello guys.

This is making me sad, the noise still there :-[
nyjumpee, no, the noise do not get worse with headlights on, night is better because is more quiet at night. But the effect is the same is like a whine/buzz coming from the engine and also changes with the RPM.

And looks like my installation is ok because this noise is introduced in to the amp after i connect the circuit, without it, there is no noise at all. I'm just guessing but i have a felling that this noise is not coming from the 12v but from the ground...

I will try two options...

Supply-1.png
I did made a headphone amp called Super Headbanger, with this i had a few problems with noise also, killing the volume i could hear a 60hz buzz in the headphone, adding a 10R resistor solve the problem, i will try the same with this one.

Supply-2.png
I will try to add the choke coil and see if the noise get better or worse.

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View attachment 39578

 

[MP1]

Here is a site that might prove to be helpful to you. It deals with troubleshooting noise such as alternator noise in your audio circuits. Perhaps something in this article will jump out at you since you are really the only one who knows how you put this project together and where wires are placed, etc...

http://www.termpro.com/articles/noise.html

MP

 

[wuemura]

Here is a site that might prove to be helpful to you. It deals with troubleshooting noise such as alternator noise in your audio circuits. Perhaps something in this article will jump out at you since you are really the only one who knows how you put this project together and where wires are placed, etc...

http://www.termpro.com/articles/noise.html

MP

Thanks MP, i wil take a look!!!

 

[wuemura]

This book does not solve the problem but gives a lot of information about ground loop and how to make a clean instalation to prevent it.
http://www.benchmarkmedia.com/pdf/caig.pdf

The book is free,
http://www.benchmarkmedia.com/caig/html/

 

[wuemura]

Much more information about ground loop can be found at this site:
http://www.epanorama.net/documents/groundloop/

 

[wuemura]

Well, adding the resistor to the ground just make things worse it amplify the noise, the choke coil makes no difference, maybe reduce the noise a bit but do not solve the problem. Next move is to feed the circuit with symetric voltage from 12v from battery, so i came up with the design bellow. I have a small and old PC speaker that i dont use any more, it uses that wall adapter (9VDC 1A) and in one of the speaker box is using this circuit to feed some opamp's that there is no mark on it,  than it goes to a very cheap speaker.

One thing i know for sure is that this thing makes no noise at all, the wall adapter has only one transformer, two diodes and a small 470uF capacitor. The 100n capacitors was my idea.

So what you think?

View attachment 39585

 

[wuemura]

Problem solved, since the noise was coming from the ground i cut and isolate the ground from the input and output RCA and rejoined with a 10 Ohm resistor, no more engine whining thanks God!
Because of the changes, the gain was reduced also, now i'm working out this issue changing the R5 100K (gain) to about 110K or maybe 120K.



PS: I'm updating the final schematic.

 

[wuemura]

No more comments? :-[

Anyway, the project is fixed, 100% working and with no noise at all. For thouse that is looking forward to build this project for your car (trust me, you will not regret this!) here is the full schematic and board design.

After you build and intall the circuit at your car, you will have to work with your fader or amp levels, with my Pioneer DEH-P6800MP i set the fader a +5 at rear.

Enjoy!
http://rapidshare.de/files/30660605/hafler-1.4.pdf