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    6th Order Help

    Didn't get much help at CACO, so I'll try here. Looking for suggestions on this design for two SA-8's. Goal is a loud daily system. Will have approximately 1000W given to the pair. Looking for near flat response from 25-60hz. Would love to be near the 140dB level, but I know that's shooting high for two 8's.

    Design
    Rear Chamber: 1.5cf @ 35hz with 15 in^2 port area
    Front Chamber: 1.5cf @55hz with 30 in^2 port area

    Just looking for general tips. Maybe a better layout can be had with my dimensions. Or different volume chambers would work better, maybe different tunings. Want to make sure it's not going to be too heavy on the upper frequencies. Really want it to pound in the 30-50hz range.

    Thanks for the help gents!

    6th Order Help-2_sa8_6th.jpg







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    Re: 6th Order Help

    according to winISD, based on your volume and tuning, it will be EXTREMELY peaky with a sharp dip in the middle. I don't believe it will be "musical".

    The response curve looks and like an "M". At around 68hz your at 0db reference, 55hz at +22db, 42hz at +5db, 35hz at +16db, 30hz at -3db.

    It looks like it will sound terrible....




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    Re: 6th Order Help

    My WinISD model didn't look near that peaky. Can you post the t/s parameters you're using? I don't have the model on my phone, but it was more like 6dB peaks at 35hz and 10dB at 55hz. With sixth orders, you're never going to get a flat response, but that doesn't mean they can't sound decent on music.




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    Re: 6th Order Help

    Actaully, it will always sound bad with 'music'. Take a look at the group delay on that 6th order.



    Quote Originally Posted by audioholic View Post
    Saying "clipping doesn't kill speakers" is a half-truth at best. Technically no, clipping itself does not hurt the speaker. But in clipping your amp, you can easily create a situation that WILL kill the speaker. Was the squared waveform the DIRECT cause of the failure? No. In the end, the answer is, always has been, and can only be... heat kills speakers. BUT, clipping increases heat generation, sometimes by a drastic amount. So to start a thread simply to state that clipping does not hurt speakers is, again, a half-truth at best.

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    Re: 6th Order Help

    The M curve you're talking about is going to be with any sixth order. That's why they're not used in sound quality builds, but you can gain a lot of efficiency in the passband. That's what I'm going for here. This is for someone with a discerning ear, so I'm not too worried about 10 dB peaks, but 20 dB is a problem. Lol. I'm thinking cabin gain is either going to help me out here, or make it even more perky. Unfortunately, I have no idea what cabin gain is here, nor how reliable WinISD is at modeling 6th order alignments.




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    Re: 6th Order Help

    Quote Originally Posted by ciaonzo View Post
    Actaully, it will always sound bad with 'music'. Take a look at the group delay on that 6th order.
    To each their own, I've heard several that didn't sound bad by any means.




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    Re: 6th Order Help

    How about a generous 4th order and let the transfer function do the rest?



    Quote Originally Posted by audioholic View Post
    Saying "clipping doesn't kill speakers" is a half-truth at best. Technically no, clipping itself does not hurt the speaker. But in clipping your amp, you can easily create a situation that WILL kill the speaker. Was the squared waveform the DIRECT cause of the failure? No. In the end, the answer is, always has been, and can only be... heat kills speakers. BUT, clipping increases heat generation, sometimes by a drastic amount. So to start a thread simply to state that clipping does not hurt speakers is, again, a half-truth at best.

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    Re: 6th Order Help

    Quote Originally Posted by ciaonzo View Post
    How about a generous 4th order and let the transfer function do the rest?
    I think I modeled a 4th and there was quite a bit more output with a 6th.




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    Re: 6th Order Help

    My WinISD model didn't look near that peaky. Can you post the t/s parameters you're using?
    I got them from the sundown website. SA8v2 D2's....

    RE: 3.36 ohms
    FS: 34.6 Hz
    VAS: 7.44 L
    Qes: 0.35
    Qms: 10.10
    Qts: 0.33
    Le: 1.34 mH
    BL: 17.56 NA
    Mms: 146.120 g
    Sens: 81.5
    RMS: 500 Watts

    It seems like the subs have too high of an EBP rating for anything other than a ported box. The 4th and 6th order setups don't come out right. Too small of a passband, especially on the 4th order if tuned low.

    That's the cost of going with 8" subs. I don't know how or why this trend with small subs got started.




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    Re: 6th Order Help

    just do a 4th order and be done ive seen 1 2 and 4 sa8.s in them and they turned out great




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    Re: 6th Order Help

    Quote Originally Posted by Beatin' View Post
    I got them from the sundown website. SA8v2 D2's....

    RE: 3.36 ohms
    FS: 34.6 Hz
    VAS: 7.44 L
    Qes: 0.35
    Qms: 10.10
    Qts: 0.33
    Le: 1.34 mH
    BL: 17.56 NA
    Mms: 146.120 g
    Sens: 81.5
    RMS: 500 Watts

    It seems like the subs have too high of an EBP rating for anything other than a ported box. The 4th and 6th order setups don't come out right. Too small of a passband, especially on the 4th order if tuned low.

    That's the cost of going with 8" subs. I don't know how or why this trend with small subs got started.

    Oh, that's why it's so different. I'm using v1 SA-8's. Here's the models I have comparing the current box, a 4th (.5cf sealed 50hz resonance, 1.5cf ported @ 50hz), and discussed 6th order. One is group delay; other is SPL at 1000W. This is figuring in a 6dB/octave cabin gain starting at 50hz. That's a pretty minimal cabin gain.
    Attached Thumbnails Attached Thumbnails 6th Order Help-sa8_3rd_4th_6th_spl.jpg   6th Order Help-sa8_3rd_4th_6th_delay.jpg  




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    Re: 6th Order Help

    Quote Originally Posted by NASTY08IMPALA View Post
    just do a 4th order and be done ive seen 1 2 and 4 sa8.s in them and they turned out great
    And this is why I'm asking for help. The both v1 and v2 SA-8's model horribly in 4th orders. Unless you tune at like 40 and don't mind having any output above 50hz, and yet people still say they've heard 4th's that turned out great.




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    Re: 6th Order Help

    all the ones ive seen have been tuned mid 30.s




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    Re: 6th Order Help

    Quote Originally Posted by NASTY08IMPALA View Post
    all the ones ive seen have been tuned mid 30.s
    That doesn't make any sense. Should've been EXTREMELY bottom heavy. Sounds like somebody was misinformed. Like almost no output above 45hz and overal output would suffer since you couldn't get sealed resonance low enough. Not saying that you're wrong, but I find that highly unlikely.




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    Re: 6th Order Help

    Quote Originally Posted by brandon_s0854 View Post
    That doesn't make any sense. Should've been EXTREMELY bottom heavy. Sounds like somebody was misinformed. Like almost no output above 45hz and overal output would suffer since you couldn't get sealed resonance low enough. Not saying that you're wrong, but I find that highly unlikely.
    ur right the numbrs dont add up but once put in the car sounded good..one of those test test test things




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