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HD Radio + Video Selector = Distortion

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  • HD Radio + Video Selector = Distortion

    I am having a bit of a problem with my directed HD radio and my kenwood kva-s300 video selector. My setup is headless, so I'm trying to run all of the audio through the pc so I have some volume control. Here is my current setup:

    HD Radio -> selector -> sound card line-in -> sound card speaker output -> EQ.

    In this configuration, I get horrible distortion from the HD radio. It sounds like all of the speakers are blown. I tried hooking another device up instead of the HD radio, and there was no distortion.

    I've also hooked up everything in this configuration:

    HD radio -> s/c line in -> s/c out -> selector -> EQ.

    When the HD radio is connected to the sound card, I don't have any distortion.

    This suggests to me that I have an issue between the HD radio and the selector.

    I tried the "ground mod" for the HD radio, and the distortion went away, however I ended up with an awful ground loop.

    So, the options I've come up with are:

    1) ground loop isolator. Hate to do this, lame fix.
    2) use the setup with the radio going to the s/c, and get a line level control to put between the selector and EQ. This makes the most sense, but I would have to reroute wires, trying to avoid this.

    That being said, does anyone have any other thoughts? Maybe something between the radio and the selector?

  • #2
    i haven't looked at the hd radio mods in a while, but here is what i try to remember:

    the ground mod was when you placed a wire between the ground power connections and the negative rca lead right? don't know if this has any effect, just checking that i am on the same page.

    also, isn't there a command to turn the volume down on the hd radio?

    i think that the volume might be too loud on the hd radio for the selector(at work, i have 2 computers, and one set of speakers, so i send 1 computers audio into the aux jack of the other computer-- if the computer that goes through the aux jack volume goes above 1/2, it outputs horrible distortion).
    My OLD 2001 Mitsubishi Eclipse GT:
    "The Project That Never Ended, until it did"

    next project? subaru brz
    carpc undecided


    • #3
      do the ground loop isolator, its not a lame fix...
      they used all the time in professional audio!
      just that the ones they use are really HQ
      but its only radio, so if you want HQ, get a Navone Engineering one
      even the "ipod" ones work fine
      you prob wont solve it any other way

      "Did you test it in carwings??"

      Sun, Come shine my way
      May healing waters bury all my pain
      Wind, Carry me home
      The fabric of reality is tearing apart
      The piece of me that died
      Will return To live again


      • #4
        Thanks for the replies!

        I think I've tracked down my problem. I was under the impression that the noise from the ground loop was coming from the equipment I added to the car. Turns out, the noise is coming from the factory subwoofers...I totally spaced on those, and didn't tie their ground in with everything else. I'm going to pull the dash apart and hook the amp ground for the subs in with everything else and see what happens. I'm pretty sure that will fix the issue, as I have the subs turned off right now and everything is quiet.

        As for the radio, I get no distortion at all when grounding the RCA cable. Previously, I would get distorted sound regardless of the volume setting. (when hooked up to the video selector.) Now it works fine at the default volume.


        • #5
          Well, turns out my factory amps have balanced inputs. I didn't know this, and was trying to hook the unbalanced input from my EQ directly into the amps.

          So, I bought a ground loop isolator from David Navone, and it's all good now! HD radio works with the ground mod, and my subwoofers are back in business.

          Thanks to everyone that replied!