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Crossover setting/hu help please.

Discussion in 'General Car Audio Discussions' started by under200, Aug 30, 2006.

  1. under200

    under200 Full Member

    As I posted earlier I have all my hardware in and it sounds pretty good. But now it's time to tweak for the perfect sound. I am totally new to the whole sub and hu crossover game so please be patient.
    Here is what I have:
    Pioneer deh-7800mp hu
    front Eclipse 6 1/2 components (about 87-40000hz)
    rear Infinity ref 6x9 (46-21000)
    Infinity basslink in trunk (20-120hz)

    Right now what I have things set at (which may be ass backwards)
    HU=
    Sub set to ON
    Sub level +1
    Stereo chosen over mono
    Freq 125hz
    Slope -12db
    Front HPF -12db
    Front HPF Freq. 125hz
    Rear HPF slope -12db
    Rear HPF freq. 125hz

    Powered sub
    Gain less than flat
    Low pass Crossover 75hz @12db
    Bass boost flat
    0 phase

    Sometimes it just sounds too boomy, looking to tighten it up. Like feeling that nice tight snap of the double bass drum.

    Thanks in advance,
    Under200
     
    under200, Aug 30, 2006
    #1
  2. TheViking

    TheViking Well-Known Member

    between the x-over in your HU and amp, that should make for a nice roll off! effectively at 75Hz. I would raise the x-over freq. of your high pass up another half octave or so and try that. Experimentation is key in doing this. No 2 installs are really the same. So their is no "SET" parameters for doing this. Granted, general common sense should ensue.! If the sound is "boomy", adjust x-overs as described. Also, try inverting the phase to your subs > set it to "180 degrees", that is out of phase with the rest of the speakers, can do wonders for the sound, especially in the midbass region. not all the time, but many times!

    Start there and let us know what happens......
     
    TheViking, Aug 30, 2006
    #2
  3. aznboi3644

    aznboi3644 Full Member

    If his high pass is set at 125hz and the sub low pass is set at 75hz...isn't there going to be a hole in the frequency spectrum??
     
    aznboi3644, Aug 30, 2006
    #3
  4. TheViking

    TheViking Well-Known Member


    No, Heres why..........

    with a roll off of 12dB per octave, and a 50 Hz spread between the two frequencies, there is ample sound below 125 Hz and above 75Hz emanating from each driver. A crossover is NOT a "Wall" that stops frequencies above or below the point of roll-off. It rolls them off..........say 100Hz high pass, at 6 dB per octave for example. At 50 Hz it is still playing music, but 6 decibals quiter than 100 Hz, and at 25 Hz, it is only 12 decibals .quiter.

    Now, the sharper the roll off, as in 12, 18 or 24 dB per octave, the faster these frequencies are rolled off, which brings into play a whole nother set of factors we would have to deal with, such as phasing, driver distances, etc.......especially in passive x-overs, which I truely loved to play with!
     
    TheViking, Aug 30, 2006
    #4
  5. aznboi3644

    aznboi3644 Full Member

    Ahh icic...I'm not familiar with the roll off slopes yet..today I learned something new...thanks Viking
     
    aznboi3644, Aug 30, 2006
    #5
  6. under200

    under200 Full Member

    Thanks for the tips. Dropped the hu crossover freq to 80hz and then I reversed the phase like Viking said. I have no scientific explanition of how flipping the phase helped but it did tighten up things a bit. Now time to tweak the eq. Probably should add an small amp to the front speakers too but I will wait a few months for that.

    Under200
     
    under200, Aug 31, 2006
    #6
  7. TheViking

    TheViking Well-Known Member

    Glad its soundig better for ya!

    The reason the sub/mid bass sounds better with the subs 180 out of phase is due to the phase effects of x-over frequencies. Also it has to do with car acoustics and speaker position. again, could make a big article on the subject!!!!
     
    TheViking, Aug 31, 2006
    #7