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  1. #1
    Join Date
    Jun 2010
    Location
    Haughton, LA
    Posts
    24

    Default Kenwood Stereo goes into "Protect" No Sound

    This weekend, I started having some issues with my stereo. When I turn up the volume past 20, it starts to crackle a little bit and eventually the front displays "Protect" and there is no sound from the speakers in the boat.

    The tower speakers and subwoofer, however, continue playing music. They are hooked up to the amp so they are unaffected it seems.

    The stereo is Kenwood KDC-MP232. I checked the battery connections and everything seems tight.

    The Protect message from the manual means "The speaker wire has a short-circuit or touches the chassis of the vehicle, and then the protection function is activated. Wire or insulate the speaker cable properly and press the reset button."

    Has anyone had this problem? I'm not much on stereo systems, so I don't really know what to do next. The connections on the back of the deck are all in. Should I unplug each speaker one at a time? Or is it more than likely the deck itself? Is there a ground on a bus bar somewhere that might be the culprit?

    Any help from you audiophiles would be greatly appreciated.
    2007 XLV Gravity Games Edition 340HP

  2. #2

    Default

    do you have an amp to the interior speakers?

    if not, you have 6 speakers hooked up to the 4 speaker output. either adjust your cross over on the deck (if it has one), add an amp, or unplug the middle set of speakers.

    We just had this problem. The deck is trying to send out 100 watts for 4 speakers the RMS on the speakers is a lot.

  3. #3
    Join Date
    Jun 2010
    Location
    Haughton, LA
    Posts
    24

    Default

    That may be the problem. I do indeed have 6 speakers hooked up to the deck. I don't believe it has a crossover, but I'll look in the manual. I'll see if unplugging the middle speakers helps. Do you unplug them from the back of the speaker, or from the wiring harness behind the deck?
    2007 XLV Gravity Games Edition 340HP

  4. #4
    Join Date
    Oct 2009
    Location
    Pacific NW USA
    Posts
    506

    Default

    Poison -

    I think Graphic nature has it close to being right. Although I dont know any deck that delivers 100W output, I have suspect you have one of two things going one.

    1 - you have a bad speaker, or a voice coil rubbing at higher volume, the speakers are heating up. That heat dissipation in a bad speaker can come across as a dead short and create havoc at your deck. you could try unplugging a couple of the speakers and see if the problem goes away.

    2 - your deck is taking a dump on you and needs to be replaced.

    ----
    As a side note: I'd recommend using an amplifier to drive your 6 speakers. doing so will give you clear crossover controls and you can isolate the frequencies that cabin speakers play best.... 90HZ and above (ok, if they are stock speakers 110Hz and above). Adding the amp will give you a noticeable improvement in output and sound quality.

    hope these tips help.

    - Brian
    Exile Audio

  5. #5
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Poison,
    With six speakers on a deck that means the four cockpit coaxials are wired two per channel in parallel for a 2-ohm load. A source unit's BTL chip amplifier is very unstable into 2-ohms and clips abruptly and very hard (falls on its face hard). Switch these rear channels to series for a resulting 8-ohm load. While you would think this will generate considerably less power in reality you will actually get more output and you'll find that the source amplifier will compress more gradually and gracefully. This change will resolve your problem until you add an outboard amplifier.
    There is a chance that you have already burnt or partially damaged a speaker voice coil or that the source unit has been damaged by running the low load.
    A failing voice coil will often have a DCR reading that is lower than the other speakers although it may not show up until the speaker is heated from usage which makes checking the DCR somewhat fleeting. It sounds a little weird but you can remove a suspected bad speaker and do the smell test. When the voice coil insulating enamel coating has begun to melt it will give off a distinct odor.

    David
    Earmark Marine

  6. #6
    Join Date
    Jun 2010
    Location
    Haughton, LA
    Posts
    24

    Default

    Thanks for the replies fellas. Sounds like the problem is definitely the 6 speakers.

    EarmarkMarine, you're reply was a little more in depth than my limited working knowledge of stereos, but I do understand basic electrics and impedance, so I'll try wiring the rear speakers in series.

    On another note, do if it comes to this, do I need to consider a marine specific amplifier to push the cabin speakers? If so, anybody have any recommendations? I'm not really much of an audiophile, I just want it to sound 'ok' when I turn it up. Doesn't need to be a top of the line amp or anything, just good enough to get me going.
    2007 XLV Gravity Games Edition 340HP

  7. #7
    Join Date
    May 2009
    Location
    Dallas, TX
    Posts
    880

    Default

    Poison,
    Sorry about the details but I'd rather be thorough.
    If you are in a coastal communty or boating in brakish conditions then you definitely need to go with a marine amplifier, something really marine and not just a white chassis. Some rivers deliver alot of salt and minerals from upstream so you've got to know your own area. Otherwise if you are in a reservoir or a fresh water environment then a non-marine amplifier may be fine. Fyi, we offer the JL Audio marine amplifiers at the same cost as the automotive units. An honest 4X100 watt amplifier at 2-ohms should power you're existing speakers and power any future upgrades with ease. For quality budget from $180 to $360 for name brand from an authorized dealer. At the low end you are looking at conventional Class AB and at the upper end you're looking at the more efficient Class D. The cheapies are generally Class B although they are not represented as such but easy to spot if you know what to look for. Feel free to shoot me an email if you would like more info.

    David
    Earmark Marine

  8. #8

    Default

    Quote Originally Posted by Brianinpdx View Post
    Poison -

    I think Graphic nature has it close to being right. Although I dont know any deck that delivers 100W output, I have suspect you have one of two things going one.

    1 - you have a bad speaker, or a voice coil rubbing at higher volume, the speakers are heating up. That heat dissipation in a bad speaker can come across as a dead short and create havoc at your deck. you could try unplugging a couple of the speakers and see if the problem goes away.

    2 - your deck is taking a dump on you and needs to be replaced.

    ----
    As a side note: I'd recommend using an amplifier to drive your 6 speakers. doing so will give you clear crossover controls and you can isolate the frequencies that cabin speakers play best.... 90HZ and above (ok, if they are stock speakers 110Hz and above). Adding the amp will give you a noticeable improvement in output and sound quality.

    hope these tips help.

    - Brian
    Exile Audio
    We are using a new Kenwood KDC-MP745U deck and (6) Polk DB 651 and then (4) Polk DB 651 on the tower.

    The towers are hooked up to an amp, but the 6 inside the boat. We adjusted the head units internal crossover, but we still can't crank it as loud as we want. It gets to a nice clean clear and loud volume and then it goes into protect mode. Once we unplugged the middle speakers, it was on! we could play the stereo as loud as we wanted.

    I do strongly advise adding an amp for the inside speakers though.

    (oh and ALL of our equipment was brand new.)

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