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panplayer 01-08-2013 08:02 PM

RFI Noise/Hiss with 2011 Legacy Limited Kenwood with Nav + HK amp/speakers
I purchased a 2011 Legacy Limited a few months ago. It has the Kenwood OEM head unit with nav + the Harman Kardon amp/speakers.

I didn't realize until after the purchase that the system emits some kind of RFI around 6.5khz. This isn't the normal noise floor deal. This is something on top of the noise floor. Also the amp was pumping at low volumes because of variable gain.

I contacted HK and one of the engineers responded, offering to replace the amp. They shipped one immediately. The gate time was much longer, and that completely eliminated the pumping issue.

NOTE: The engineer at HK has been great. They have provided excellent customer service. They really are trying.

However, what I presume to be RFI remains. So I guess this means that either a) there is a poorly placed cable (near some source of RFI) or b) there is a problem with the Kenwood OEM head unit.

Anyone else with this problem?

SBT 01-09-2013 05:36 AM

Where are you located?

panplayer 01-10-2013 05:28 AM

North Carolina

panplayer 01-10-2013 09:08 PM

And I guess really this would be EFI, not RFI. Whatever it is, it is certainly annoying.

panplayer 01-13-2013 05:48 PM

Any ideas? Know anyone I can contact? The dealer doesn't understand the problem....

sigmafour 01-13-2013 06:22 PM

Kenwood have had a bit of a rep the last few years or so of having very noisy boards - it would not surprise me if this is related to that same kind of issue. How much effort are you willing to put in to identify the problem with this stock HU? I've got suggestions for discovery and possible solution but it will involve tinkering around with the stock wires and breaking them open...

panplayer 01-13-2013 06:28 PM

Think it could just be a bad ground somewhere?

panplayer 01-13-2013 06:31 PM

i guess what I am saying is... yes, I'd be willing. But just thinking ahead, is it possible to change that HU out and keep the same amp/speakers?

ssbtech 01-14-2013 01:56 PM

Gotta ask the stupid question: Any noise with the volume at 0? I only ask because my head unit also makes a noise, but not in the speakers. It's the VFD and the noise gets slightly louder when the brightness is turned up a bit on the display.

panplayer 01-14-2013 04:59 PM

Not a stupid question at all! No noise at 0. And again, the 'noise' isn't the normal noise floor that almost all of those systems produce. I swear I think this is coming from the display or some other source of EFI.

Curious you should mention the display. There is an option to turn it off temporarily, but I still hear the noise, even when off. But I'm going to go play with the display brightness.

Now I need to ask a question. What's the VFD?

(and thanks for taking the time to read/respond!)

ssbtech 01-14-2013 05:21 PM

Vacuum Fluorescent Display

As for your noise - I'm guesing it's the head unit. If Subaru is still using speaker level outs to the H/K amp, it's highly unlikely the wiring is picking up any electrical noise.

Is it RPM dependant? Present when running the radio from the battery with the engine off?

panplayer 01-14-2013 06:26 PM

Gotcha. The display is LED. I think.

I believe these are line level inputs on the amp. I can check with HK.

This is not RPM dependent. It centers around 6.5k. I have a recording of it, but not sure where to post it.

ssbtech 01-14-2013 06:31 PM

Stick it up on Youtube?

panplayer 01-14-2013 06:42 PM

Could be. Only thing is that the audio quality will kinda suck.

panplayer 01-14-2013 06:48 PM

Check your private messages. Just sent it to you.

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