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Thread: Midbass Null

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    Midbass Null

    Hi guys,

    Hoping for some advice in dealing with a null in the listening position. Sitting in drivers side (RHD here in Aus), the left mid bass measures and sounds great ( HAT L6SE), but the right mid bass pretty much has zero authority and this is confirmed by measurements.

    However, when I measure from the passenger side, the problems switch (i.e. Right MB is good, Left MB is bad) which indicates to me a null?

    Any ideas what I can do? I know EQ isn't the answer...

    Hopefully the pics make sense...these are with no EQ applied. Door mounted in a Mazda 3. From memory, the cross over is 63Hz/24dB LR - 249Hz/24dB LR.

    Thanks!
    Click image for larger version. 

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  2. Back To Top    #2

    Re: Midbass Null

    Can't speak to the "right" way, but some "tricks" I've seen work- try switching the polarity of one of the drivers and/or play with the time alignment. you're probably experiencing comb filtering where the opposing drivers are canceling in a given range.
    Last edited by slade1274; 04-26-2016 at 08:51 AM.

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    Senior Member chithead's Avatar
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    Re: Midbass Null

    Agreed, I've read phase swapping could be a potential fix, and time alignment as well.
    Are you not entertained?!?!


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    Noob Babs's Avatar
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    Re: Midbass Null

    Can we clarify if you're getting these measurements with just one driver playing (left OR right, but not both)?
    If you're getting this null with just one driver playing, it's a modal destructive problem between the driver and the car and it's kind of symmetrical, if that makes sense because it's effecting both seats opposite each driver. (console, cabin resonance/cabin gain, etc)
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  5. Back To Top    #5

    Re: Midbass Null

    Size of the car cabin creates the null. Can't do a thing about it - else you have to move your midbasses

    Kelvin

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    Re: Midbass Null

    Quote Originally Posted by subwoofery View Post
    Size of the car cabin creates the null. Can't do a thing about it - else you have to move your midbasses

    Kelvin
    I second this statement. Listening compartment is a huge world of compromises and will never be perfect.
    "Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid."
    -Albert Einstein

  7. Back To Top    #7

    Re: Midbass Null

    Guys,

    Measurements are drivers on their own.

    Would it be helpful to provide one with both midbass playing and say each side with the sub?

    Thanks for the comments!
    Tim

  8. Back To Top    #8

    Re: Midbass Null

    Another strange thing, if it makes any sense to anyone...

    A long time ago, the with the L6SE mounted the *exact same* way in the door. no Changes to baffle, sound deadening etc. But running the drivers from the stock wiring running off my 80PRS internal amp (while building amp rack etc). There was *Heaps!!* of mid bass. It sounded amazing!

    Every since I installed my amps (three iterations) of: JL Audio HD600/4 bridged (300W), JL Audio HD600/4 single channel (150W) and now my current setup of Helix P SIX DSP (120W) the mid bass has been the same. Lacking.

    I just can't see what else has changed?

  9. Back To Top    #9

    Re: Midbass Null

    that explanation screams of a crossover problem coming off the preamp output of the deck, since the built-in amp is capable of delivering the right frequency set through it's own set. It could be a defect in the deck that isn't noticeable unless one actually uses a sophisticated testing method to slew out where the drop is happening.

    or the use of an outboard processor is gunking up your mid bass spread?

    I'd be very suspicious if the inboard chip amps can make mid bass but an amplified solution falls short.

  10. Back To Top    #10

    Re: Midbass Null

    and using the factory wiring shouldn't make a difference but maybe there's something in that, as well. If several amp attempts all yield poor results or "null" and deck power is generating the full waveform at the seat, it's not a dimensional issue or even an installation issue, it's something else not physical or determined by physics.

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