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Thread: Electric crossover overlap

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    Noob swrocket's Avatar
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    Electric crossover overlap

    Have a question about electric crossover settings.

    I'm using a minidsp CDSP 8x12 (no DIRAC) with 10 bands of PEQ per driver to tune to a Half Whitledge curve created using Jazzi's spreadsheet.
    Acoustic crossovers are SUB: HP 20 - LP 90, MB: HP 90-> LP 335, MR: HP 335 - LP 2800, TW: HP 2800 (all LR24)

    I took full range measurements and now using REW to match the drivers to the curve.
    To get to the correct curve without crazy cuts or boost, I find that my electric crossovers between MB and MR are overlapped. The MB is LP at 450 BU6 and the MR is HP at 320 BU2.

    Will this cause issues?

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    Re: Electric crossover overlap

    You can’t get them to match because of reflection created dips, you need to either move the crossovers as a whole (because it sounds like both have dips at the same place...) and overlapping with crap phase in a crossover for both drivers will not make the stage any better or sound good

    do you have any area where there are all cuts?

    When people say that the install makes an sq system, this is why, positioning driver so they don’t have phase dips at the same places is the key

    is yours factory locations? If so it’s making the best of a bad job, or if not... moving one of the drivers to move the phase issue so you get clean overlap so you can get good phase through the crossover, peaks in crossovers are old one because reflected and direct are in the same phase and so will sum nicely... dips you have two polaritys of wave so whatever you do you won’t get the other driver to sum, this is worst when both drivers have 0 and 180 degree waves at the listening position

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    Noob swrocket's Avatar
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    Re: Electric crossover overlap

    Unfortunately, I do have to use factory locations. I have cancellations due to reflection in the midranges which are in the dash corners (both at around 1900) and I plan to try positioning those better to try and raise that cancellation above 3K so that the tweeters can compensate.
    But, for the Midbass, there are common dips at around 400 and I cannot move them...
    Here are the full range response curves with no EQ (MR have a x-over at 110 and TW at 1100 for protection). I tried several different xover points and eq'd them to the curves and I can get the stage centered and pretty focused, but tonality sucks
    Click image for larger version. 

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    Re: Electric crossover overlap

    The bad in those is the tweeter bottom end (left I think) if they do have 1100 crossovers on them I would remeasure those once more as I have had helix processors not change the frequency when swapping about, and until you manually change the channel it then almost catches up...

    also are the mid and tweeter close together?

    and to move the phase issue to double the frequency you will need to move the driver twice as close to all reflective surfaces, angling or a cm spacer won’t cut it sadly

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    Noob swrocket's Avatar
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    Re: Electric crossover overlap

    Quote Originally Posted by dumdum View Post
    The bad in those is the tweeter bottom end (left I think) if they do have 1100 crossovers on them I would remeasure those once more as I have had helix processors not change the frequency when swapping about, and until you manually change the channel it then almost catches up...

    also are the mid and tweeter close together?

    and to move the phase issue to double the frequency you will need to move the driver twice as close to all reflective surfaces, angling or a cm spacer won’t cut it sadly
    The mids are in the dash corners firing into the windshield and the tweeters are in pods on the a-pillars firing on-axis. The tweeters are closer to me than the mids. On the driver side (LHD) it's about 8" difference and the passenger side about 5" difference. I don't know what's causing the right midrange dip at 320Hz though...on the driver side there is a huge bump in the dash from the guage cluster and I expected that to cause a dip...the passenger side is completely flat.
    I'm not sure I understand what you mean about the tweeter response and changing the channel...I measured these several times and they always have the same response.
    I should mention that I'm using an AF UMI-1 mic on the headrest and me outside the car.

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    Noob Jdunk54nl's Avatar
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    Re: Electric crossover overlap

    It really doesn't matter electrical settings (dsp settings). If the speakers response at the listening position matches a 24db/oct LR curve, then your phase at the listening position should be good as you can get with basic measurements like that.

    I have my electrical crossovers all over the board but every speaker matches the target curve when measured in the listening position.


    This is from my wife's car. All of these are set for acoustical 24db/oct LR slopes at 80hz and 2500hz. NONE of these are set in the dsp as 80/2500hz LR 24db/oct crossovers. I have butterworth, linwitz, some others with 6db, 12db, 18db, whatever it takes to get the acoustical response I want. This was done with a dayton dsp 408.

    Note: Factory HU heavily cuts the bass at 40hz....it sucks but it is what it is and I "restored" it the best I could without introducing too much distortion.

    Click image for larger version. 

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    Last edited by Jdunk54nl; 01-23-2021 at 11:20 AM.
    2014 F150 Limited -> Kenwood DDX-9907xr -> Helix DSP.2 -> Alpine PDX-V9 -> SI M25 mki in Valicar Stuttgart Pods, Rear SB17's, Sub SI BM MKV's in MTI BOX. Alpine PDX-F6 -> SI Tm65 mkIV, SI M3 mkI in Valicar Stuttgart Pods

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    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Electric crossover overlap

    Quote Originally Posted by swrocket View Post
    To get to the correct curve without crazy cuts or boost, I find that my electric crossovers between MB and MR are overlapped. The MB is LP at 450 BU6 and the MR is HP at 320 BU2.

    Will this cause issues?
    Having "strange" crossover frequencies to make your acoustic response work right?
    No problem at all. I encourage it.
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

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    Noob swrocket's Avatar
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    Re: Electric crossover overlap

    Using different electric slopes and types I knew, I was just wondering if the overlap in electric x-overs would cause issues even when the responses are matched to the LR24 slopes. Seems like it should be ok.
    I was also considering having asymmetric acoustic crossovers for left MB-MR and right MB-MR but I'll see how this goes first.

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    Wave Shepherd - aka Jazzi Justin Zazzi's Avatar
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    Re: Electric crossover overlap

    Quote Originally Posted by swrocket View Post
    I was also considering having asymmetric acoustic crossovers for left MB-MR and right MB-MR but I'll see how this goes first.
    Asymmetric electronic filters is normal and encouraged.

    Asymmetric acoustic filters is ... different? I'm curious how that goes!
    Measure with mics, mark with chalk, cut with torch, grind to fit, sand to finish, paint to match.
    Updated Justin tuning sheet (Justin and Erica tuning companion for SMAART and REW)
    Do it for them.

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    Noob swrocket's Avatar
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    Re: Electric crossover overlap

    So, after struggling with this response curve (midrange) for a while I was chatting with my son and he says, "oh, maybe it's that rattling I can hear on that side..."
    Turns out the dash trim was not snapped in place properly and was rattling against the windshield, also the negative speaker wire was loose at the crimp (it came out when I lifted the speaker) AND I forgot to put gasketing tape on the speaker flange...I really screwed this install up
    I'll fix and reinstall then measure again.

    I have some questions about proper install of speakers in dash but I'll post in the fab and install forum.

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