Kenwood head unit issues, popping and static.

[chussey]

Hello everyone,

I just installed a Kenwood KDC-X997 single DIN head unit into my 91 NSX, retaining the stock Bose speakers and amps. I am getting my speaker signals from the RCA outputs of the Kenwood headunit. All audio worked properly with the stock Bose headunit.

The problem is I get a loud popping sound when:
-The radio turns on
-The radio turns off
-I change tracks when using USB storage
-I turn the volume down from 1 to 0
-I turn the volume up from 0 to 1

If I disconnect my RCA connections from the headunit, there is no popping sound (and also no audio).

I also have a relatively quiet static sound any time the radio is on, even if the volume is off. I assume this is the stock amps being powered on but not having any music sent to them? The static goes away if I put my head unit into standby mode.

Do any of you audio experts know what the problem could be?

 

[Speedmaster]

Not an expert but when I was replacing radios in my cars I always had to add an inline fuse. Not sure that is necessary with the new electronics, but 1991 and amps, I would expect to.

 

[BTL3.0]

You need some ground loop isolator.. happened to me when i had my alpine double din in.
http://www.crutchfield.com/S-GtDIcLWDsY6/p_127SNI1/PAC-SNI-1.html

something like that. You onlh need 1, i repeat only 1.. nsx only have 1 channel.. get that and the pop noise will go away.

 

[chussey]

You need some ground loop isolator.. happened to me when i had my alpine double din in.
http://www.crutchfield.com/S-GtDIcLWDsY6/p_127SNI1/PAC-SNI-1.html

something like that. You onlh need 1, i repeat only 1.. nsx only have 1 channel.. get that and the pop noise will go away.

Thanks, just ordered the isolator.

Sure looks like two channels though...

http://www.scienceofspeed.com/produ.../stereo_wire_harness/afterhead-factoryamp.jpg

 

[BTL3.0]

I too thought it was 2 channels, bought 2 isolators. To find out you only need 1. I believe our nsx only use the front channel. Sub is wired into that channel also.

 

[jwmelvin]

In other words, you are both right. Two channels = L & R. And one isolator does two channels.

 

[chussey]

I too thought it was 2 channels, bought 2 isolators. To find out you only need 1. I believe our nsx only use the front channel. Sub is wired into that channel also.

I currently have four RCA preamp output channels from my headunit connected, same as the SOS adapter harness. Through the head unit I am able to fade the audio front to back, as well as left to right. Would this mean that both front and rear outputs are being used?

Maybe only one pair of channels need to be isolated to eliminate the noises, rather than all four?

 

[BTL3.0]

I would try 1 first and see.

 

[jwmelvin]

I currently have four RCA preamp output channels from my headunit connected, same as the SOS adapter harness. Through the head unit I am able to fade the audio front to back, as well as left to right. Would this mean that both front and rear outputs are being used?

Maybe only one pair of channels need to be isolated to eliminate the noises, rather than all four?

Yes, the way you have it hooked up, you can fade front-back to change the balance between door speakers and the sub. The center-rear is tied in with the sub; you may wish to disconnect it. And the way you have it hooked up, you will need two isolators. There's nothing wrong with that.

 

[BTL3.0]

Yes, the way you have it hooked up, you can fade front-back to change the balance between door speakers and the sub. The center-rear is tied in with the sub; you may wish to disconnect it. And the way you have it hooked up, you will need two isolators. There's nothing wrong with that.

Thank you for clarifying.

 

[chussey]

Yes, the way you have it hooked up, you can fade front-back to change the balance between door speakers and the sub.

Is there another way to hook it up?

The center-rear is tied in with the sub; you may wish to disconnect it.

Is there a reason to disconnect any of the speakers?

 

[jwmelvin]

Is there another way to hook it up?

Sure, you can hook up L & R front outputs to both the L & R door amps and the sub-center amp. There is no advantage of doing so unless you really want to be locked into the factory sub-main balance. Or, as is my case, if you only have a two-channel source (Bluetooth adapter).

Is there a reason to disconnect any of the speakers?

I didn't see any reason to connect the center speaker just because I don't really want to hear sound behind me. But then again, I find the stock sound system seriously lacking in nearly every regard.

 

[chussey]

Sure, you can hook up L & R front outputs to both the L & R door amps and the sub-center amp. There is no advantage of doing so unless you really want to be locked into the factory sub-main balance. Or, as is my case, if you only have a two-channel source (Bluetooth adapter).

I didn't see any reason to connect the center speaker just because I don't really want to hear sound behind me. But then again, I find the stock sound system seriously lacking in nearly every regard.

So neither of the above situations apply to my car (and most NSX), as there are four output channels, and I see no reason to remove any of the speakers. Thanks for the input though.

I will be installing the ground loop isolators tonight, hopefully they solve the issue.

 

[jwmelvin]

So neither of the above situations apply to my car (and most NSX), as there are four output channels

I'm not sure why you say most NSX have four output channels. The factory radio does not have the ability to fade; it only has two output channels.

 

[chussey]

I'm not sure why you say most NSX have four output channels. The factory radio does not have the ability to fade; it only has two output channels.

Two?

 

[jwmelvin]

My point was merely that the stereo has two channels, L and R, regardless of having four connections to the amps. I'm not sure it's all that important, and I do think it's best to connect front and rear if your interfacing an aftermarket deck to the OEM amps.