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Thread: Tweeter help

  1. #11
    Join Date
    Dec 2011
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    denver co
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    84

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    Now thats a good idea. Maybe david will give us some input on crossover settings. HP settings for 650's and hp settings on rev 10's and a rev410. LP settings for 2 jl audio 10w3's. And what the hell is slope. I've got the gain settings down. Thanks
    Quote Originally Posted by kaneboats View Post
    You raise a good point. Lots of us kind of "tune" (for lack of a better word, maybe "set" would be better in my case as lots of you would laugh at my attempts to "tune" anything-- I can't tuna fork) at the time of an install or addition to the system. Then we just leave it. Maybe we should all consider a "retune" each spring as we prepare for the year and a checkup tune periodically as well.

  2. #12
    Join Date
    Dec 2011
    Location
    denver co
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    David thats so true and to make things worse, stereo in the boat must be like meth. Put it in and oh thats good. After a while it's man I could use a little more.
    Quote Originally Posted by EarmarkMarine View Post
    Thanks, but I was just trying to get my post count up.
    I'm glad we saved you the cost and hassle of the extra tweeters.
    It's funny, or not so funny, how often people form a fixed and unbreakable opinion based on a one time exposure to a poorly designed, poorly tuned/set, or poorly executed product or system.
    In a similar way to your experience, the smallest details can acummulate to have either a significant positive or negative impact on the system quality. Box/woofer design, box tuning frequency, crossover selection, gain structure, system efficiency, and countless other layers can have more to do with the final performance than the particular product.

    David

  3. #13
    Join Date
    May 2009
    Location
    Dallas, TX
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    880

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    " And what the hell is slope. "

    This is easy to explain in graphic form but a mess to explain verbally. I'll try.
    You have highpass filters that cut out the lows. You have lowpass filters that cut out highs. These filters reference a certain frequency or crossover intersection where typically both the highpass and lowpass are -3 dB down (half power).
    Ideally the two sides, both at -3 dB, will then sum through the crossover region for 0 dB and a smooth transition.
    The filters do not work like a brick wall. They start at a more gradual "slope" above the crossover frequency and settle into a fixed and steeper slope below the crossover frequency. The slope represents the level of attenuation per octave once that filter has settled into the fixed slope. -3 dB is half power. -6 dB is one quarter power. And so on.
    a 6 dB slope is a 1st order. (-6 dB attenuation per every octave).
    a 12 dB slope is a 2nd order.
    18dB=3rd order.
    24dB=4th order.
    With any non-linear change in amplitude you have a corresponding phase shift. The inverse is also true. The two are inseparable and law. Not like a polarity change of 180 degrees, but more of a phase rotation from 0 to 90 degress for a 1st order filter, for example. Each filter slope has a particular phase rotation as the filters progress.
    How does this apply to a crossover? Differently in each application. Different vehicles with different dimensions, different products, different speaker locations relating to different wavelengths, etc. uniquely benefit from different filter slopes.
    Typically you want a symmetrical crossover with as little overlap as possible because the low and high pass filters are going through opposing phase shifts. This will aid a coherent transition. Many other issues can contribute to a phase shift so you may run asymmetrical crossover points or slopes to compensate.
    Understanding all these issues and being to use these tools allow you to repair certain problems that an equalizer cannot.
    Of course, you have to be able to first identify the issues you have.
    That's really the tip of the iceberg.
    For us, setting up gain structures and crossovers is according to a particualr prescription that we have written specifically for boats. It is independent of product. Even the intermediate version is a book. But we assist our customers step by step on a level that they are comfortable with. Usually with we stick to the basics. Several of the members here have been through the short process. It's not like root canal. But tuning can make a gigantic difference between two systems that are otherwise equal.

    David

  4. #14
    Join Date
    Dec 2011
    Location
    denver co
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    84

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    David I think I got it. Most of it anyways. No overlap on HP and LP as the slope will aid in the transition. Only question is the higher the db the quicker the slope or drop off?

  5. #15
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    May 2009
    Location
    Dallas, TX
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    Yes, within the in-boat zone use the same frequency for both highpass and lowpass to keep the overlap region to a minimum, assuming that the amplitude of the lowpass and highpass are equal. Just realize that if you increase the sub level over the highpass level, you widened the overlap and may want to reset the lowpass frequency to compensate.
    Normally in an open-field environment I prefer the shallower 12 dB slope over the steeper 24 dB slope.
    David

  6. #16
    Join Date
    Dec 2011
    Location
    denver co
    Posts
    84

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    Thank you, sounds like a tune up is in order this spring.

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