Hi, spent weekend upgrading the system in my Landrover Discovery 3, and now pulling my hair out with noise.
The problem -
Whining (prob from alternator) increase with RPM
Buzzing noise when I switch on the lights, or use the air suspension setting
Crackle on application of brake pedal
The setup
Factory base headunit retained
Hi level to low level signal convetors (brand audioleads) - fitted in the kickpanels to speaker wires
Amp - Kenwood KAC PD650 - 5 channel
Sub = Hertz 250D DVC
Front speakers - DLS RS6 component with passive crossover in the doors
Rear speaker - Focal CA165 two way
The whole thing sound great and clear at high volume - when I turn the volume low or to zero I notice the whinning etc mentioned above, from all speakers except for the sub, which is driving my nuts.
I have tried the following:
Try different rca leads run outside the car - no effect
Move RCA converter to very close to the amp - no effect
Re ground the amp - no effect
Move cables further apart - no effect
Isolate amp completely on a rubber mat - no effect
Run ipod/PC connected straight to amp via RCA - Need to try but don't think this is it since when the amp is on but upconnected to the input source no noise
Not sure what to do next
Don't really know where to go from here,
Any help would be great,
Thx
Replies (11)
kirchatndftbl on 06/2/2008 08:45:39
make sure rca's arent near any power wires of any sort.
try grounding the factory HU better, the extra gear might be too much for the factory ground to handle
ttocs on 06/2/2008 11:39:12
you probably need to move the loc's up closer to the deck to minimize the amount of noise the factory wire picks up before you tapped it for its signal. I always recomend putting them up there so that if you replace the deck you can just plug the cables in but also if you have noise then move it closer to the source.
swez on 06/2/2008 16:37:06
If the LOC's have a gain control feature, try adjusting them to attenuate noise, but still pass adequate audio signals back to this amp. As ttocs mentioned, it better to locate the LOC's close to the signal source. (HU)
Noting the things you have tried and how other vehicle features come into play, it might be worth trying a "dedicated ground" for the HU. (Not the dash harness ground line only)
All the classic signs of "ground loop problems" are mentioned and are most notable at low signal output levels from the stock HU. The last thought here, is to reduce the amp gain sensitivity settings until the noise is gone. It seems like there are low level noise issues at work here and the suggested tweaks may resolve them.
Swez
D3Kuli on 06/2/2008 20:42:17
kirchatndftbl ,ttocs, Swez Thanks for the helpful suggestions.
The LOCs don't have a gain control feature, I did play with the Amp gain and yes the noise does reduce when I turn it right down but it doesn't sound as good.
I will try the following based on the above:
New ground (dedicated) for the HU - Would this be best to the firewall? Also should I just cut the earth and create new one or just splice into it and attach to firewall?
Move the LOCS to behind the HU - should I ground those to the same point or an independant one?
I will have a another go this weekend and let you know how I get on
Thanks again
Kuli
D3Kuli on 06/10/2008 07:18:02
Ok, Headunit now on a new ground to firewall and no longer factory harness ground - no effect
Checked Voltage at Battery, Headunit and amp - all the same 12.74volts
Ran ipod direct connection to amp - no noise
The only thing left to try is moving the LOCs to directly behind the headunit rather than the kick panels - will try over the next couple of days
Any other suggestions??
SQLThump on 06/10/2008 07:32:18
Make sure power and signal wires are wired as far away from each other as possible, and definitely use good sheilded RCA cables. Look to spend 30-40 bucks or more for some high quality stuff.
Also, what size wire are you using for power and ground, and how long is your gound for the amp??
D3Kuli on 06/10/2008 07:50:40
Earth cable is less than 1 Metre,
Power cable is thick about 10mm diameter - thicker than recommended.
Earth cable is not as thick but thicker than recommended
RCAs shielded - have already tried replacing them and running then outside the car
Power cable runs down the middle of the car, and RCAs under the door sills either side of the car
Should I consider trying different LOCs if moving them closer to the Headunit does not work?
SQLThump on 06/10/2008 08:55:06
Boom, Upgrade your ground cable. Although they say to use the same size for both power and ground, using less than a meter, personally I think going ahead and going a size bigger and using less than 30CM would be the way to go, then their is no question.
What are you grounding to as well? Make sure we are using a nice, paint removed piece of the car body, (not a bolt or something), that is connected with its own fasteners for the matters of making sure that is pinned down.
Moving two things should prove very useful, the power cable completely to one side of the vehicle, and RCA's sompletely to the other. Moving the LOC should also be done ASAP.
If you list what year your Rover is, and specifically what factory H/U you have, I may be able to help you out some more. My brother is an expert in BMW factory audio/navigation integration, and many Rovers share many identical parts (my bro uses a Rover screen in his 740) and we may be able to pin down some more stuff from there.
After this, does your amp have a high level (pigtail connector) input? With this, we can attempt to bypass the LOC completely, as many of them have had problems with noise. Also, how well is your LOC grounded? This is very important.
Hit us back, we'll get this pegged for sure....
SQLThump
swez on 06/10/2008 09:20:03
Since you ran the I-pod direct to amps and had no noise issues, this noise is definitely upstream in the signal path and the LOC mentioned here may not be adequate or in a poor location at the moment.
Also, some vehicles have data bus lines that may be too close to the LOC's now. That might be a good part of the problem or you made need a better quality LOC to nail down this noise issue. A quality LOC has excellent noise rejection circuits, quality coils and variable resistors are often employ for gain adjustments too. Many of the better ones come in 2/4 channel models and are well isolated to reject noise. Some can handle high power HU's and factory amp signals too.
The Pro Installers in this group can tell you the better brands to consider and how to use them properly. (Ttocs, UK Installer, Victor are far more knowledgable on this one than me) I defer to their experience when needed and suggest you do the same.
Finally, if this model has a 12 volt trigger and ground line, consider grounding it to the same place as the HU and tap your +12 volts from the HU power line as well. Keeping these wires short and close to the HU should help reject noise as well.
Good luck,
Swez
D3Kuli on 06/10/2008 23:12:28
Thanks for the help guys - I only really get a chance on the weekend to play with it.
Car is a Land Rover Discovery 3 - LR3 in the US - 2007 car
I will have another go this weekend with the above suggestions starting with the LOCS
Amp ground is to a new drilled hole, painted sanded off direct to the car body under body - I can use a bigger cable and shorten in by about a half
Ttocs, Victor - can you recommend a different LOC to try?
SQLThump on 06/11/2008 10:22:36
Right on. The regrounding mya not fix your noise issues, but trust me, you will thank yourselkf later when you see tho much better it will perform.
I did ask my bro if he knew any of the specifics of the LR3's stock stereo, and unfortunately, he is not familair with the system.
Hopefully new LOCs closer to the H/U will do the trick.
The problem -
Whining (prob from alternator) increase with RPM
Buzzing noise when I switch on the lights, or use the air suspension setting
Crackle on application of brake pedal
The setup
Factory base headunit retained
Hi level to low level signal convetors (brand audioleads) - fitted in the kickpanels to speaker wires
Amp - Kenwood KAC PD650 - 5 channel
Sub = Hertz 250D DVC
Front speakers - DLS RS6 component with passive crossover in the doors
Rear speaker - Focal CA165 two way
The whole thing sound great and clear at high volume - when I turn the volume low or to zero I notice the whinning etc mentioned above, from all speakers except for the sub, which is driving my nuts.
I have tried the following:
Try different rca leads run outside the car - no effect
Move RCA converter to very close to the amp - no effect
Re ground the amp - no effect
Move cables further apart - no effect
Isolate amp completely on a rubber mat - no effect
Run ipod/PC connected straight to amp via RCA - Need to try but don't think this is it since when the amp is on but upconnected to the input source no noise
Not sure what to do next
Don't really know where to go from here,
Any help would be great,
Thx
Replies (11)
kirchatndftbl on 06/2/2008 08:45:39
make sure rca's arent near any power wires of any sort.
try grounding the factory HU better, the extra gear might be too much for the factory ground to handle
ttocs on 06/2/2008 11:39:12
you probably need to move the loc's up closer to the deck to minimize the amount of noise the factory wire picks up before you tapped it for its signal. I always recomend putting them up there so that if you replace the deck you can just plug the cables in but also if you have noise then move it closer to the source.
swez on 06/2/2008 16:37:06
If the LOC's have a gain control feature, try adjusting them to attenuate noise, but still pass adequate audio signals back to this amp. As ttocs mentioned, it better to locate the LOC's close to the signal source. (HU)
Noting the things you have tried and how other vehicle features come into play, it might be worth trying a "dedicated ground" for the HU. (Not the dash harness ground line only)
All the classic signs of "ground loop problems" are mentioned and are most notable at low signal output levels from the stock HU. The last thought here, is to reduce the amp gain sensitivity settings until the noise is gone. It seems like there are low level noise issues at work here and the suggested tweaks may resolve them.
Swez
D3Kuli on 06/2/2008 20:42:17
kirchatndftbl ,ttocs, Swez Thanks for the helpful suggestions.
The LOCs don't have a gain control feature, I did play with the Amp gain and yes the noise does reduce when I turn it right down but it doesn't sound as good.
I will try the following based on the above:
New ground (dedicated) for the HU - Would this be best to the firewall? Also should I just cut the earth and create new one or just splice into it and attach to firewall?
Move the LOCS to behind the HU - should I ground those to the same point or an independant one?
I will have a another go this weekend and let you know how I get on
Thanks again
Kuli
D3Kuli on 06/10/2008 07:18:02
Ok, Headunit now on a new ground to firewall and no longer factory harness ground - no effect
Checked Voltage at Battery, Headunit and amp - all the same 12.74volts
Ran ipod direct connection to amp - no noise
The only thing left to try is moving the LOCs to directly behind the headunit rather than the kick panels - will try over the next couple of days
Any other suggestions??
SQLThump on 06/10/2008 07:32:18
Make sure power and signal wires are wired as far away from each other as possible, and definitely use good sheilded RCA cables. Look to spend 30-40 bucks or more for some high quality stuff.
Also, what size wire are you using for power and ground, and how long is your gound for the amp??
D3Kuli on 06/10/2008 07:50:40
Earth cable is less than 1 Metre,
Power cable is thick about 10mm diameter - thicker than recommended.
Earth cable is not as thick but thicker than recommended
RCAs shielded - have already tried replacing them and running then outside the car
Power cable runs down the middle of the car, and RCAs under the door sills either side of the car
Should I consider trying different LOCs if moving them closer to the Headunit does not work?
SQLThump on 06/10/2008 08:55:06
Boom, Upgrade your ground cable. Although they say to use the same size for both power and ground, using less than a meter, personally I think going ahead and going a size bigger and using less than 30CM would be the way to go, then their is no question.
What are you grounding to as well? Make sure we are using a nice, paint removed piece of the car body, (not a bolt or something), that is connected with its own fasteners for the matters of making sure that is pinned down.
Moving two things should prove very useful, the power cable completely to one side of the vehicle, and RCA's sompletely to the other. Moving the LOC should also be done ASAP.
If you list what year your Rover is, and specifically what factory H/U you have, I may be able to help you out some more. My brother is an expert in BMW factory audio/navigation integration, and many Rovers share many identical parts (my bro uses a Rover screen in his 740) and we may be able to pin down some more stuff from there.
After this, does your amp have a high level (pigtail connector) input? With this, we can attempt to bypass the LOC completely, as many of them have had problems with noise. Also, how well is your LOC grounded? This is very important.
Hit us back, we'll get this pegged for sure....
SQLThump
swez on 06/10/2008 09:20:03
Since you ran the I-pod direct to amps and had no noise issues, this noise is definitely upstream in the signal path and the LOC mentioned here may not be adequate or in a poor location at the moment.
Also, some vehicles have data bus lines that may be too close to the LOC's now. That might be a good part of the problem or you made need a better quality LOC to nail down this noise issue. A quality LOC has excellent noise rejection circuits, quality coils and variable resistors are often employ for gain adjustments too. Many of the better ones come in 2/4 channel models and are well isolated to reject noise. Some can handle high power HU's and factory amp signals too.
The Pro Installers in this group can tell you the better brands to consider and how to use them properly. (Ttocs, UK Installer, Victor are far more knowledgable on this one than me) I defer to their experience when needed and suggest you do the same.
Finally, if this model has a 12 volt trigger and ground line, consider grounding it to the same place as the HU and tap your +12 volts from the HU power line as well. Keeping these wires short and close to the HU should help reject noise as well.
Good luck,
Swez
D3Kuli on 06/10/2008 23:12:28
Thanks for the help guys - I only really get a chance on the weekend to play with it.
Car is a Land Rover Discovery 3 - LR3 in the US - 2007 car
I will have another go this weekend with the above suggestions starting with the LOCS
Amp ground is to a new drilled hole, painted sanded off direct to the car body under body - I can use a bigger cable and shorten in by about a half
Ttocs, Victor - can you recommend a different LOC to try?
SQLThump on 06/11/2008 10:22:36
Right on. The regrounding mya not fix your noise issues, but trust me, you will thank yourselkf later when you see tho much better it will perform.
I did ask my bro if he knew any of the specifics of the LR3's stock stereo, and unfortunately, he is not familair with the system.
Hopefully new LOCs closer to the H/U will do the trick.
Copyright ClubKnowledge 2009 * All Rights Reserved
