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Feedback Request: First Attempt At X-Over

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  • Feedback Request: First Attempt At X-Over

    Hi All,

    I'm looking for some feedback on my first attempt at speaker building. A few months ago, I had jumped on a deal for a pair of Hi-Vi 2.2 Speaker Kits (included a DIY cabinet, D6.8 IIB woofer, and Q1R tweeter).

    After assembling, I was pretty disappointed with the sound: Long story short, the system response was pretty much a gradual 11db increase from 100hz - 20KHz (bass response was very poor)

    Given the small investment, I decided to recycle some of the parts (i.e. tweeter and cabinet) and try and attempt x-over design.

    I picked a pair of Vifa P17 off of CL. Given the larger woofer diameter, I enlarged the current woofer cutout and installed a stepped baffle for the Vifa.

    I've attached the project as it stands and was hoping fellow forum experts can provide their feedback.

    Overall, given the high resonance frequency of the tweeter (1Khz), a 4th order acoustic crossover was selected. From what I've read, I understand it is recommended that the x-over point should be at least 1 (preferably 2) octaves above a drivers resonance frequency. Current x-over point is 2.3Khz, which I'm hoping is high enough to protect the tweeter and low enough the not result in significant beaming from the woofer.

    I tried my best to keep the x-over components to minimal. I also tried to maximize the use of parts on hand. Lastly, I was trying to get the drivers to have reasonable phase matching over the x-over region.

    My biggest concern right now is a low impedance of 3.4ohm at 2.9Khz. The predicted electrical phase at 2.9Khz is -23 degrees. I'm hoping the combination is benign but am looking for feedback.

    Given this low impedance concern, I did attempt another crossover (also attached) - but for some strange reason, the first attempt sounds better to my ears.

    Any thoughts would be much appreciated.
    Attached Files

  • #2
    Looks fine to me. Maybe try increasing c5 a little, and see if the impedance comes up a little.

    Comment


    • #3
      You might consider adding some baffle step compensation, especially if the speakers will be on stands out away from the wall.

      Comment


      • #4
        Originally posted by rpb View Post
        Looks fine to me. Maybe try increasing c5 a little, and see if the impedance comes up a little.

        rpb - increasing C5 seems to only impact the 200hz - 700hz range.


        Billet,

        The picture of the speaker posted above was taken when I was taking response measurements (i.e., maximum distance from boundaries). The speaker will be eventually placed much closer to room boundaries - I would expect the baffle to be no more than 20" away from the back wall.

        In the speaker measurement position, the speaker does sound quite lean. The pictures above only show response down to 100hz. I'll try to post the quasi-anechoic response (using Jeff B. suggested method) later this evening.

        Thanks again for posting feedback.

        D

        Comment


        • #5
          If your HiVi woofer was the D6.8, and your cab's about 0.5cf (14L?), then the HiVi should reach down near 40Hz, whereas that Vifa (which really wants a box 3x that size) should barely break 60Hz. Another "drawback" of the P17(WG-00-06) is that its Xmax is kinda "puny" at only 3mm. Dayton's DC160 would make bass in that box.

          Comment


          • #6
            Originally posted by Chris Roemer View Post
            If your HiVi woofer was the D6.8, and your cab's about 0.5cf (14L?), then the HiVi should reach down near 40Hz, whereas that Vifa (which really wants a box 3x that size) should barely break 60Hz. Another "drawback" of the P17(WG-00-06) is that its Xmax is kinda "puny" at only 3mm. Dayton's DC160 would make bass in that box.

            Chris the HiVi kits came with a different version of the D6.8, which I understand to be a well performing driver.

            The Hivi kits included the D6.8IIB woofer. After attempting to break them in, and taking T/S measurements with DATS, it didn't seem the driver was well suited for the 14L enclosure.

            See post : http://techtalk.parts-express.com/fo...27#post1345127

            I believe forum member johhyrichards had similar findings with the kit he purchased.


            The Vifa utilized in my build was the Vifa P17WJ-00-08. It was a vintage driver that measured no were near factory specs. Nonetheless, I was simply wanted to experiment with it.
            I was wondering how long that thread would last. Pushing away customers from the PE forums doesn't seem like a good idea.

            Comment

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