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General K5 / Jimmy stereo system question

Discussion in 'Audio' started by flash_point, Nov 23, 2001.

  1. flash_point

    flash_point Registered Member

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    Does that fiberglass shell on the K5's & Jimmy's add more bass pounding to a system? Just curious.
     
  2. flash_point

    flash_point Registered Member

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    Damn not to many people visit the audio board??
     
  3. jarheadk5

    jarheadk5 1/2 ton status

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    Actually there's a bunch of regulars on this board, some of which are real audio professionals.

    As far as the shell goes, I THINK it would tend to make a clean bass hit sound "muddy" but I don't know for sure. If you throw some Dynamat on the inside of the shell, the whole system will likely sound better.
    Wait 'till Monday or Tuesday, the regulars will be here and you'll get a better answer from people who KNOW.

    Ken

    <font color=blue>America--Land of the Free, Home of the Brave<font color=black>
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Flash,

    Are you referring to the "bass pounding" relative to whether the top is installed vs. removed?

    If that is the question, then the answer is YES. Any hardwall top will help to contain the bass and give you more sound pressure at a given volume setting.....there is a phenomenon called a "transfer function" which happens inside an enclosed space (your vehicle) that tends to re-inforce and actually BOOSTS bass frequencies.

    It is somewhat common-sense, but you will not get the "transfer function effect" with a soft-top installed...[​IMG] A soft-top will behave sonically like an open-top vehicle.

    I designed and built a HUGE system for my "open top" K5 this past summer...recently when I put the fiberglass top on again, I was reminded how MUCH bass is lost into the open air. The bass was so overwhelming, that I actually re-tuned the system to reduce to output of the subs. There was simply TOO MUCH bass with the top installed.

    Hopefully that's the answer to your question, if I missed the point of you question let me know and I'll try again! [​IMG]



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  5. flash_point

    flash_point Registered Member

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    Thanx for the response. What I was trying to find out is if the K5's &amp; Jimmy's are better vehicle's for stereo systems opposed to the regular car w/ a trunk or a hatchback. That's when I asked about the fiber glass shell cause I was wondering if the bass vibrations that bounced off the shell help make the bass sound bigger than a regular vehicle. That's all I was trying to refer to, did that make any sense?
     
  6. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    You're asking does the fiberglass top act almost like a "drumskin" and vibrate....adding more bass?

    The answer is that any object will have a 'resonant frequency' at which it will begin resonating along with the test tone being bounced off it. The problem is that those resonant frequencies are very narrow (only a few Hz for the bass stuff you're interested in) and so all you are really doing is getting a "droning sound" by exciting that resonance with your stereo.

    The reason people use things like Dynamat is to make the object heavier and denser....by doing that, it's 'resonant frequency' is moved lower in the frequency range, and it generally takes more 'energy' to excite the resonance in the first place.

    OK.....that's kind of the long answer. The short answer is this:

    Yes, a hardtop WILL vibrate at certain frequencies. But NO, it does not add a 'pleasing sound' to the music. You've got to have a LOT of power though, before this resonance even becomes an issue....it's hard to get a fiberglass top to resonate.



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  7. flash_point

    flash_point Registered Member

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    Cool, thanx. When I get my Blazer I'm planning on doing a crazy system setup. For instance my Firebird has four 12"'s, &amp; I was thinking about that same setup in the Blazer or four 15"'s. Just trying to plan it out in my head &amp; on paper.
     
  8. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Four 15's huh.....? That should do it!!!!! [​IMG]

    No problems feeling the bass.....or blowing the windows out!



    -Greg72

    '72 K5 Blazer - 427BB/TH350/NP205/6" Lift/35x12.50's
    <font color=blue>See it here: </font color=blue><a target="_blank" href=http://coloradok5.com/gallery/albun38>http://coloradok5.com/gallery/albun38</a>
     
  9. '73 K5

    '73 K5 1/2 ton status

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    When I was in high school I had a '79 K5. I went from 2 18's to 4 15's my senior year. When I had the 18's I had access to an AudioControl RTA. Hit 140 with 8 gauge power cable and no caps. Then I upgraded to 4 gauge and a 1.5 farad cap and the 15's...too bad I never got around to measuring that setup.
    Let me just say that hearing Zombie's Thunder Kiss '65 was an experience that can't be put into words. I can't believe I'm not deaf yet.

    '73 K5
    Chevy good...Ford bad
     

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