Center of the Sun update

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  • Patrick Sun
    Super Senior Member
    • Aug 2000
    • 1380

    Center of the Sun update

    Update: Day 13 (4/21/01)

    I start the revamp of the new crossover network with Linkwitz-Riley crossovers (all 2nd order filters).

    Graph 26: Although you can't tell from this graph (which includes a Zobel on the midrange driver in an attempt to normalize the impedance at its high end response level of 3500Hz), there was some really nasty midrange cone breakup (wailing sounds) because I crossed the midrange over too high (around 3250Hz). This meant I had to re-do the midrange section. This just goes to show you that you get something to "measure well" and sound like poop. The tweeter has a L-pad with 6dB of attenuation, but it's still too "bright". But with the midrange wailing, I can't discern how much more padding I need on the tweeter just yet.

    Graph 27: I remove the Zobel from the midrange, and decide to lower its lowpass crossover point to around 2000Hz to take advantage of its rising response until it gets to the tweeter crossover frequency around 3250Hz. I keep a 2nd order L-R filter for that midrange lowpass, but this cuts out a little too much of the speaker's vocal quality, so it's something that needs to be addressed in the next crossover. I also push the woofer's lowpass crossover point to 1000Hz in an effort to get some response around 500Hz, but it doesn't help as much due to the L-R filter 6dB/octave slope. This leads me to introduce some Butterworth filters in my next set of changes in the crossover network. Also, the tweeter output is still too high, around 2-3dB too high.

    Graph 28: I use a Butterworth on the woofer and cross it over at 700hz. Then I use a 1st order Butterworth filter for the lowpass on the midrange at 2000hz to allow the midrange to be "active" until I cross the tweeter over at 3250Hz, where the midrange's output starts to fall off. I then replaced the tweeter L-pad with one that put the brakes on its output with a -8.5dB L-pad. While the new overall response looks peaky in spots, it sounds more natural, especially voices, which is a major consideration for a center channel speaker. I will use this crossover network for the time being unless I think I can improve it some more.

    I listened to a few DVDs with 5.1 audio, and I was pleasantly surprised by the consistent soundstage I was getting with the new crossover in place. It was just a more coherent sound field that I was hearing now. I then listened to some Dolby Pro-Logic sources (taped shows from this past week), and the vocal quality has improved as well. I'm finally getting the front 3 speakers plus the subwoofer integrated better than before. I can finally call this an improvement over my original setup now.

    So, after I veneer the enclosure, I will be done with this project. I have already picked up some red oak veneer, so it's just a matter of time to get it completed soon.

    (To see the rest of the story, click on the DIY CC link in my signature below). It seems the original thread has been wiped from this server.

    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
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