MM6501 Driver Frequency Response - Active setup

grateful72
grateful72 Posts: 38
edited April 2012 in Car Audio & Electronics
Hi all.

One of my tweeters went bad and has been replaced with a dayton tweeter that only plays down to 3,500 hz. At the same time I am going to active setup.

Anyone know how hign I can set the low pass filter for the mm6501 driver?
Post edited by grateful72 on

Comments

  • Face
    Face Posts: 14,340
    edited April 2012
    A 6.5" driver shouldn't be used above 2.5, 1.8k optimally.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • grateful72
    grateful72 Posts: 38
    edited April 2012
    Dskip. I did buy 2 tweeters.

    2500?. I guess i'll try it with tweeter crossed at 3,500.

    Polk told me passive crossover was ~3,000 for original tweeter. But didnt tell me crossover for mid (if its the same or if there is a slight gap)
  • arun1963
    arun1963 Posts: 1,797
    edited April 2012
    Face wrote: »
    A 6.5" driver shouldn't be used above 2.5, 1.8k optimally.

    Not true in a car. Most 6.5" mids will be linear till about 3-3.5khz. Most 0.75"-1" tweets will struggle below this point in anycase. The SR mids are flat all the way to 5khz.

    The MM mid will be good to ~ 4-5khz.
  • grateful72
    grateful72 Posts: 38
    edited April 2012
    Thanks Arun1963.

    Makes me feel better. Now I can crossover my tweets tonight a bit higher and ease the stress on my tweeter. I will try 5 khz and move down from there if need be.
  • heiney9
    heiney9 Posts: 25,165
    edited April 2012
    What does it matter, it's not really a Polk speaker anymore. It's just some drivers with an active x-over.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
  • grateful72
    grateful72 Posts: 38
    edited April 2012
    Wow...thanks Heiney. Real helpful. It's still a Polk driver that has certain specs that I can't find anywhere. Sorry if I did not want to spend $100 on replacement "Polk" tweeters.
  • Face
    Face Posts: 14,340
    edited April 2012
    arun1963 wrote: »
    Not true in a car. Most 6.5" mids will be linear till about 3-3.5khz. Most 0.75"-1" tweets will struggle below this point in anycase. The SR mids are flat all the way to 5khz.

    The MM mid will be good to ~ 4-5khz.
    You're saying there are no break up nodes before 5K?
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
  • pentoncm
    pentoncm Posts: 379
    edited April 2012
    i run mine active up to 4k on a 24db/octave filter and I have no trouble. They sound good. Your far side is going to be hotter of course from 2.5k on up, so L/R would help a lot. I tried opening them up just to hear what they sound like up to 10k, while they don't sound as good as tweeters do that high, they certainly aren't bad, so the break up must not be too bad.
    Audison Bit Ten
    Kenwood X595
    Polk MM6501
    Polk MM1240
    Mtx 704x
    Alpine MRX50
  • arun1963
    arun1963 Posts: 1,797
    edited April 2012
    Face wrote: »
    You're saying there are no break up nodes before 5K?

    No. Breakup nodes are not intrinsically bad as nearly all drivers will have them at certain frequencies. They just happen to be one indicator of where it is ideal to implement a crossover with specific drivers. Frequency response plots or CSD plots don't tell the whole story. In most cases, they show up as a nub, ripple, or bump in the impedance plot. In the higher octaves a more rigid cone (woven glass like the MM or PP like the SR's) will normally have lesser nodes in the passband.

    A higher xover point will require greater levels of dsp, if you're going for pure sq. But even without dsp it can work as long as the mids and tweets are not too far seperated.