After I changed the speakers in my car the speakers are whining

jfholloway
jfholloway used Ask the Experts™
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I replaced a set of JL Audio component speakers with a pair of Polk component speakers and now I have a whine from my speakers that gets louder as the engines rev's up. There are 2 amps in the car that were not changed. I also used the wiring from the original JL speakers. Does anyone have any ideas on what the problem is? I had no problems before the speaker swap.
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JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
In theory it should not matter, but you could try reversing the leads to the speaker(s) .

Did the other speakers perhaps have a filter inside them?

Are the speakers the same match (speaker impedance)?
Distinguished Expert 2017

Commented:
the new one has treble that the older did not have
You need to add filters on the amp power  the interference is often from the variations of the generator.
You also got a lower impedance speakers than the others were.
This would explain why the noise is more pronounced.
With more sensitive speakers you need more suppression.
The whine from your speakers that gets louder as the engines rev's up is from the ignition coils & or the alternator RF noise.
Use ignition coil & alternator RF noise suppression capacitors sold at any automotive accessory shop to reduce the noise.
If that is not sufficient then you will need to rewire the speakers with RF shielded wires.

The car model may help with advice.

Regards,
Michael
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jfhollowaySr. Systems Administrator

Author

Commented:
the car is a 2001 Trans-am with  4 Polk db6501 speakers (these are the new speakers), 2 amps a Kenwood KAC-8402, Kenwood 2 channel amp (don't rememeber the model#) and a Pioneer Avic-5000nex head unit.
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

Commented:
Did you try any suggestions above: Impedance Mismatch and other suggestions?

Also check ground of the speaker casing if it allows for it.
Distinguished Expert 2017

Commented:
An impedance mismatch would usually alter the power output, the distortion isuggests that the new have a lower impedance, though supported
Usually amps have/support 8/4 ohm speakers.  The noise mightnothave been heard with the older 8ohm speakers are detectable with the new 4ohm with a Twitter that might not have been present in the prior set.the lower impedance makes them more sensitive to noise propagating into the audible.
It is Alternator Noise which can be eliminated with a RF noise suppression capacitor fitted to the alternator.
Also make sure all stereo components are grounded to the chassis.
You can get a RF noise suppression capacitor at any auto parts accessory shop.

Reading on this "Alternator Noise"
http://www.carstereo.com/help/Articles.cfm?id=71

The new speakers have a wider frequency range are more sensitive to RF noise.

Hope this helps.
jfhollowaySr. Systems Administrator

Author

Commented:
while i have been testing different points of contact for the amps I wiggled the one of the RCA cables negative connector to the amp and the noise got louder. I swapped the RCA cables around and still the same issue. I think the problem might be with the amp and the negative post for one of the RCA connections. I guess the next thing is to replace the amp and if that is the problem.
The change of speakers may have coincided with another electrical fault???

Can you test with the older speakers to rule this possibility out ?

The whine from your speakers that gets louder as the engines rev's up is from your Alternator Noise

Regards,
Michael
Distinguished Expert 2017

Commented:
before you go replacing the AMP, see whether the speakers of old and the new are similar in spec.
Add a filter on the power/ground on the amp.
You will be kicking yourself if you go an buy a new amp while having the same issue.
jfhollowaySr. Systems Administrator

Author

Commented:
I believe I figured out the issue. After watching a video on YouTube I broke out the ohm meter and the electrical schematic for the car and tested every ground point in the car. It said any reading above 3-4 ohms was a ground problem. After 3 hours of searching and testing grounds I found a ground that was over 5 ohms. I cleaned the connection and ground point on the car. The reading dropped to 2.8 ohms and the whining noise went away. I'll see over the next day or two if that fixed the issue.
2015-07-06 at 20:38:40ID: 40868367
"Also make sure all stereo components are grounded to the chassis."
Most spark plug manufacturers offer a "resistor type" sparkplug just for this purpose.  NGK and Champion both do.  They are available at any auto parts store. The plug will have the same part number but with an "R" added.  You may already have them, but you may want to check.

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