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Thread: Crossover for 2.1

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    Crossover for 2.1

    I was reading the audiofrog tuning guide and not sure I understood the ideas listed for setting sub crossover 1/2 octave lower than midbass.

    I have a 12" sub (SWS12D4 ported), NVX XSP65 mids, and nvx VSPTW Tweeters and trying to get a good starting point for crossovers.

    DSP: original mosconi 6to8

    This is what I am thinking I need:
    sub: LR-12+LR-12 High Pass 20, Low Pass 80
    mid: LR-12+LR-12 high Pass 100, low Pass 2500
    twe: LR-12+LR-12 high pass 2500

    My thoughts were that I would get a flat response with 10db boost below 60hz (unless i misunderstood the audiofrog tuning guide)

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    BURNED OUT Hillbilly SQ's Avatar
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    Re: Crossover for 2.1

    It looks like crossing half an octave below is to help maintain acoustical phase for up front bass. In a car we need a boost in bass to sound natural but that causes a bad actual cross point between the sub and midbass if both cross points are at 80hz for example. Hopefully I got the wording correct on that.
    They might say "don't try this at home" but nothing about not trying it at your friend's house.

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    Re: Crossover for 2.1

    That is what I took out of the article, my confusion was the example with 12db crossovers, It made me question if the same response graph would occur when using a phase matched crossover like LR-24db.

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    Re: Crossover for 2.1

    It messes with it because you are trying to cross the sub over at 80hz and the sub is 12db higher than the mid (lets call this mid level 0db) for the extra bass, and LR drops it 3db at the crossover, the sub is still 9db higher at 80hz. We want it roughly -3db at 80hz just like the mid is with the LR crossover.

    To accomplish this if we set the sub crossover at 60hz, it is 9db higher than the midbass at 60hz (down by 3 for the LR crossover) and by 80hz it has dropped another ~10db when using a 24db/oct slope to get it to roughly -3db at 80hz.

    If we don't adjust the crossover, then your sub and mid are really crossing at like ~130hz and that is where the phase issues come into play.

    You can also accomplish this if you do a shelf filter. Level match the sub and mids together and then apply a shelf filter to them both for like 100hz and below.
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    Re: Crossover for 2.1

    If your mids have a HP of 80 Hz than you would put a LP on the subwoofer 1/2 octave lower at 60 Hz. Use 24 db Linkwitz Riley crossovers instead of 12 db.
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    Re: Crossover for 2.1

    just a heads up, if you are following the audiofrog guide, use LR 24 slopes.

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    Re: Crossover for 2.1

    Quote Originally Posted by SkizeR View Post
    just a heads up, if you are following the audiofrog guide, use LR 24 slopes.
    what they said ^^ although I think he is using 24db slopes looking at his tweeter crossover, it’s a high pass with double 12db slopes which is how mosconi make you do it... it’s far easier to tell if drivers are in phase properly as well using rew if you have a mic with them anyway

    I’d also stick to 80hz hpf and 60hz low pass filter on the sub, that way the actual crossover point is preserved and higher than 60hz anyway due to the sub being louder than the midbass/mid in your case

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    Re: Crossover for 2.1

    Quote Originally Posted by dumdum View Post
    what they said ^^ although I think he is using 24db slopes looking at his tweeter crossover, it’s a high pass with double 12db slopes which is how mosconi make you do it... it’s far easier to tell if drivers are in phase properly as well using rew if you have a mic with them anyway

    I’d also stick to 80hz hpf and 60hz low pass filter on the sub, that way the actual crossover point is preserved and higher than 60hz anyway due to the sub being louder than the midbass/mid in your case
    Ok, starting to make more sense now. I will change to the 80/60 crossover on mid/sub to realize an perceived crossover of 80hz.
    sub: LR-12+LR-12 High Pass 20, Low Pass 60
    mid: LR-12+LR-12 high Pass 80, low Pass 2500
    twe: LR-12+LR-12 high pass 2500


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