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  • Need help with revamped 110s

    Hi guys. The large 3-way speakers that I brought to last year's MWAF are called "The 110s". They originally used three 8" Peerless India buyout woofers, a buyout Peerless v-line 5.25" mid, and a Vifa neo tweeter. I've decided to replace the v-line mid with the Dayton DC50F-8 to increase overall system sensitivity and to better match the output of the woofers, but I'm having some issues in regards to the crossover. With a 2nd-order high-pass filter to the DC50 at around 600 Hz, there's audible distortion coming from the mid.

    Any suggestions for a 2nd-order crossover frequency for the DC50F-8 to avoid these distortion problems? The 8" woofers have decent response up to 1 kHz. Thanks.
    Eric L.

  • #2
    Re: Need help with revamped 110s

    Originally posted by brkitup View Post
    I've decided to replace the v-line mid with the Dayton DC50F-8 to increase overall system sensitivity and to better match the output of the woofers, but I'm having some issues in regards to the crossover. With a 2nd-order high-pass filter to the DC50 at around 600 Hz, there's audible distortion coming from the mid.
    Here's how Paul Carmody used it in the 'DCR':
    http://techtalk.parts-express.com/at...6&d=1297400218
    He used a xover point of about 900Hz.

    I think the first thing I would do is see if the impedance has a large Fs spike, or if it's ferro-fluid cooled.
    http://www.parts-express.com/pdf/285-010s.pdf

    It does not appear to be damped with FF, so you will likely have to compensate for the Fs in some form or fashion. You can use say a 10 ohm resistor across the mid to help damp it, or go for a full LCR to kill it completely without reducing output. This is a very common ailment with dome-mids, but the LCR cures a lot of problems. There is also a little bump about 1.8kHz in the impedance that corresponds to the dip/peak in the FR at the same point. You will also have to use a shunt-notch to nuke that unless it's not objectionable. My guess is that it will be, and it may flatten out after you fix that.

    If the LCR does not remove the issues, then you'll need to step up to a 3rd electrical HP. I find lots of times that this is something that just has to be done to control the excursion- another cause for Dome-mid distortion.

    I would not advise increasing the xover point to 1khz, as that makes the blending between the mid and bottom woofer more problematic, and you'll have comb-filtering to a degree. Most of the time, dome mids xover between 700-800 Hz, but I think the DC50 can do what you are asking of it with some more details.

    I see it lending well to 600 and 4kHz for xover points, as long as this stuff is in check. You'll likely have to damp the knee on the LP to remove the rise above 4kHz. (Think first order + zobel, even though that is actually a damped-12dB xover. The values are not from a true-zobel, so maybe 1-3 ohms on the resistor.)

    Just some things to think about,
    Wolf
    "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
    "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
    "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
    "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

    *InDIYana event website*

    Photobucket pages:
    https://app.photobucket.com/u/wolf_teeth_speaker

    My blog/writeups/thoughts here at PE:
    http://techtalk.parts-express.com/blog.php?u=4102

    Comment


    • #3
      Re: Need help with revamped 110s

      Originally posted by Wolf View Post
      Here's how Paul Carmody used it in the 'DCR':
      http://techtalk.parts-express.com/at...6&d=1297400218
      He used a xover point of about 900Hz.

      I think the first thing I would do is see if the impedance has a large Fs spike, or if it's ferro-fluid cooled.
      http://www.parts-express.com/pdf/285-010s.pdf

      It does not appear to be damped with FF, so you will likely have to compensate for the Fs in some form or fashion. You can use say a 10 ohm resistor across the mid to help damp it, or go for a full LCR to kill it completely without reducing output. This is a very common ailment with dome-mids, but the LCR cures a lot of problems. There is also a little bump about 1.8kHz in the impedance that corresponds to the dip/peak in the FR at the same point. You will also have to use a shunt-notch to nuke that unless it's not objectionable. My guess is that it will be, and it may flatten out after you fix that.

      If the LCR does not remove the issues, then you'll need to step up to a 3rd electrical HP. I find lots of times that this is something that just has to be done to control the excursion- another cause for Dome-mid distortion.

      I would not advise increasing the xover point to 1khz, as that makes the blending between the mid and bottom woofer more problematic, and you'll have comb-filtering to a degree. Most of the time, dome mids xover between 700-800 Hz, but I think the DC50 can do what you are asking of it with some more details.

      I see it lending well to 600 and 4kHz for xover points, as long as this stuff is in check. You'll likely have to damp the knee on the LP to remove the rise above 4kHz. (Think first order + zobel, even though that is actually a damped-12dB xover. The values are not from a true-zobel, so maybe 1-3 ohms on the resistor.)

      Just some things to think about,
      Wolf
      Lots of good suggestions there, Wolf. I think I really should consider a 3rd-order filter. I was hoping to just modify the existing crossover a bit, but it looks like a complete rebuild. I'll let you know how it turns out, and I'll probably bring them to InDIYana. Thanks.
      Eric L.

      Comment


      • #4
        Re: Need help with revamped 110s

        Glad I could help!
        Oh- one more thing- if the woofers have a second order elec on them, then a 3rd elec HP is warranted to help keep your phase in check.

        See you in about 47 days!
        Wolf
        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

        *InDIYana event website*

        Photobucket pages:
        https://app.photobucket.com/u/wolf_teeth_speaker

        My blog/writeups/thoughts here at PE:
        http://techtalk.parts-express.com/blog.php?u=4102

        Comment

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