I installed a Pioneer DEH-p8600MP dec into my car along with 2 amps (1 for front speakers, 1 for rear deck speakers). Since the install I've had alternator whine (pitch changes with RPMs). I've checked the ground on the amps (both are good), re-grounded the deck itself, installed ground loop isolators on each set of RCA cables, and check to make sure the RCAs are not running near the power cables. I've also adjust the input sensitivity on the amps to no avail. What else could be causing the whine and what can I do to resolve the problem
Replies (11)
ttocs on 01/19/2007 01:22:18
try disconnecting the rca's at the back of the deck. if the noise stops then you need to look at your deck. While disconnected connect the center pin of the RCA to the outer shield with the deck on. If the noise continues with the pin connected, you might have a bad rca. Try running a temp set over the carpet to see if it stops then.....
swez on 01/19/2007 10:42:51
WARNING WILL ROBINSON .... if we short the RCA center and ground together, this can damage the HU RCA preamp circuits when they have power flowing from the HU.
On the surface, it sounds like you have done everything right out of the text book for ground loop isolation problems. However, the whine remains. In this case, an AUX ground from the HU chassis to the amps might be in order.
Here, we take a fine gage wire, (#18) and attach it to the HU chassis ground and run this back to the amps and ground that line to the amp chassis.
Also, when grounding both amps, use the same location as their grounding point. A seat belt harness bolt that is sanded and paint/debris free to bare metal. At the HU, we often recommend grounding to the floor pan, under the carpet. This too is bare metal. Sometimes the harness ground at the HU is not sufficient for aftermarket HU's.
What brand RCA's are you using here? Some brands have better noise rejection as they use twisted pairs of conductor and these generally do a very good job at noise cancellation. (Street Wires or Knukonceptz)
Say more please,
Swez
shank210 on 01/19/2007 11:19:28
Im not sure of the brand on RCAs, they were bought a while ago. They do seem to be of decent quality but I will check them again. As for grounding the HU I already grounded it directly to the floor pan. The front speaker amp is located under the dash and the rear speaker amp is located in the truck. Swez, as you said I should try connecting a fine wire from the HU chasis ground back to each one of the amps chasis grounds? Eventually I will change around the set up of my system with both speakers being located in the trunk, but for now I want to fix this issue and enjoy the music!
swez on 01/19/2007 14:40:35
Right... I see your point and understand.
Are you getting whine noise from both amps or just the front stage amp now? I ask this as dash mounted amps have some issues that might lead to noise. In the dash, the amp is in close proximity to many wires, heater blower and other noise generating devices. Moving both amps to the trunk is often a good option.
For now, can you try grounding the front channel amp at the same location as HU? (Or, ground the HU wire to the amp ground) This may or may not help, but worth a try.
Swez
UKinstaller on 01/19/2007 19:33:46
it's the outputs on the pioneer head unit causing it i'm sure. run a ground wire to the shields of each RCA jack until the noise is gone, or get a different brand deck.
-UK
shank210 on 01/19/2007 23:56:25
UK- Ive already run a ground to the shields of the RCA...didnt help. Swez I get whine from both amps but its a more pronounced in the front amp. The HU already is grounded at the same ground point as the front amps ground. I thought that maybe being mounted under the dash might be the cause but since I also get whine from the rear Im assuming that isnt the cause.
cplkittle on 01/20/2007 01:26:06
You never answered if the RCAs are running with or on the other side of the car as the power wire.
Also, do you have an equalizer or anything else connected?
What brand are the amplifiers?
shank210 on 01/20/2007 09:37:44
I stated in the beginning that my RCAs are not run near the power wire. I do not have an equalizer or anything else connected and the amps are both Lanzar Opti series amps
swez on 01/20/2007 15:02:03
Again, on paper and the printed word, you have done all the key steps to eliminate normal issues with Alternator whine. Pioneer HU's seem to have a propensity for engine noise, due to inadequate grounding at the RCA's as mentioned by UK Installer. This often helps.
The only other thing I can think of now, is to use a filtering cap between the ALT output and ground it to the engine block or mounting hardware. All newer GM ALT's use an internal filter in their integrated regulators. However, yours may not be doing the job. Older cars had these mounted as noted, but it's been so long since I have seen them, I don't know what value of cap to recommend.
Perhaps you can find that Cap at an autoparts shop that still supports pre-1980 vehicles. (NAPA comes to mind)
The only other thing I can suggest is moving your amps to the trunk and using quality twisted pairs of RCA's. The twisted pairs tend to do the best at noise cancellation, short of balanced line outputs.
Swez
shank210 on 01/21/2007 02:55:08
UK what deck (with close to the same specs and price) would you recomend?
swez on 01/22/2007 16:35:39
Kenwood, Eclipse, Blaupunkt and Alpine all come to mind as possible replacements.
Swez
Replies (11)
ttocs on 01/19/2007 01:22:18
try disconnecting the rca's at the back of the deck. if the noise stops then you need to look at your deck. While disconnected connect the center pin of the RCA to the outer shield with the deck on. If the noise continues with the pin connected, you might have a bad rca. Try running a temp set over the carpet to see if it stops then.....
swez on 01/19/2007 10:42:51
WARNING WILL ROBINSON .... if we short the RCA center and ground together, this can damage the HU RCA preamp circuits when they have power flowing from the HU.
On the surface, it sounds like you have done everything right out of the text book for ground loop isolation problems. However, the whine remains. In this case, an AUX ground from the HU chassis to the amps might be in order.
Here, we take a fine gage wire, (#18) and attach it to the HU chassis ground and run this back to the amps and ground that line to the amp chassis.
Also, when grounding both amps, use the same location as their grounding point. A seat belt harness bolt that is sanded and paint/debris free to bare metal. At the HU, we often recommend grounding to the floor pan, under the carpet. This too is bare metal. Sometimes the harness ground at the HU is not sufficient for aftermarket HU's.
What brand RCA's are you using here? Some brands have better noise rejection as they use twisted pairs of conductor and these generally do a very good job at noise cancellation. (Street Wires or Knukonceptz)
Say more please,
Swez
shank210 on 01/19/2007 11:19:28
Im not sure of the brand on RCAs, they were bought a while ago. They do seem to be of decent quality but I will check them again. As for grounding the HU I already grounded it directly to the floor pan. The front speaker amp is located under the dash and the rear speaker amp is located in the truck. Swez, as you said I should try connecting a fine wire from the HU chasis ground back to each one of the amps chasis grounds? Eventually I will change around the set up of my system with both speakers being located in the trunk, but for now I want to fix this issue and enjoy the music!
swez on 01/19/2007 14:40:35
Right... I see your point and understand.
Are you getting whine noise from both amps or just the front stage amp now? I ask this as dash mounted amps have some issues that might lead to noise. In the dash, the amp is in close proximity to many wires, heater blower and other noise generating devices. Moving both amps to the trunk is often a good option.
For now, can you try grounding the front channel amp at the same location as HU? (Or, ground the HU wire to the amp ground) This may or may not help, but worth a try.
Swez
UKinstaller on 01/19/2007 19:33:46
it's the outputs on the pioneer head unit causing it i'm sure. run a ground wire to the shields of each RCA jack until the noise is gone, or get a different brand deck.
-UK
shank210 on 01/19/2007 23:56:25
UK- Ive already run a ground to the shields of the RCA...didnt help. Swez I get whine from both amps but its a more pronounced in the front amp. The HU already is grounded at the same ground point as the front amps ground. I thought that maybe being mounted under the dash might be the cause but since I also get whine from the rear Im assuming that isnt the cause.
cplkittle on 01/20/2007 01:26:06
You never answered if the RCAs are running with or on the other side of the car as the power wire.
Also, do you have an equalizer or anything else connected?
What brand are the amplifiers?
shank210 on 01/20/2007 09:37:44
I stated in the beginning that my RCAs are not run near the power wire. I do not have an equalizer or anything else connected and the amps are both Lanzar Opti series amps
swez on 01/20/2007 15:02:03
Again, on paper and the printed word, you have done all the key steps to eliminate normal issues with Alternator whine. Pioneer HU's seem to have a propensity for engine noise, due to inadequate grounding at the RCA's as mentioned by UK Installer. This often helps.
The only other thing I can think of now, is to use a filtering cap between the ALT output and ground it to the engine block or mounting hardware. All newer GM ALT's use an internal filter in their integrated regulators. However, yours may not be doing the job. Older cars had these mounted as noted, but it's been so long since I have seen them, I don't know what value of cap to recommend.
Perhaps you can find that Cap at an autoparts shop that still supports pre-1980 vehicles. (NAPA comes to mind)
The only other thing I can suggest is moving your amps to the trunk and using quality twisted pairs of RCA's. The twisted pairs tend to do the best at noise cancellation, short of balanced line outputs.
Swez
shank210 on 01/21/2007 02:55:08
UK what deck (with close to the same specs and price) would you recomend?
swez on 01/22/2007 16:35:39
Kenwood, Eclipse, Blaupunkt and Alpine all come to mind as possible replacements.
Swez
Copyright ClubKnowledge 2009 * All Rights Reserved
