My adventures with a 2.5-way XO

Discussion in 'Archived Threads 2001-2004' started by Patrick Sun, Oct 27, 2001.

  1. Patrick Sun

    Patrick Sun Moderator
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    Here's the response graph of what I think I've settled on as my "final" filter crossed around 280Hz for the 0.5 midwoofer (it's basically the same filter as I started with - had to see if others made a difference):
    Graph 1
    That hump in the 100-140Hz region can be a little bassy, but it doesn't sound as bad as it looks on the graph (plus it's a matter of speaker placement in the room).
    I tried other filters crossed higher (around 355/400/500hz) but they all tended to boost the frequencies from 80-2000Hz too much because the rolloff was too shallow, and the 0.5 midwoofer was contributing too much, which muddied up the output.
    Here's a recap of not so good filter results:
    I had to use parts on hand, so I didn't have too many crossover points that could be realized quickly). I didn't bother to measure the 1.0 midwoofer response, but did measure the overall combined midwoofers' response shown for the following graph, as well as the 0.5 midwoofer's response.
    (crossed around 355Hz)
    Graph A
    BTW, the judges at DIY2001-Atlanta heard the XO version shown above (with a minor tweak on the tweeter/1.0 midwoofer XOs which tried to move the XO point down from 2.3KHz to 2KHz rather messily), and the main complaint was it was too
    bassy, and dank, and the midrange was mud. After taking the measurements, I know why.
    (crossed around 400Hz)
    Graph B
    (crossed around 500Hz)
    Graph C
    I'm hoping this finishes off the XO for my 2.5-way's.
    ------------------
    PatCave; HT Pix; Gear; DIY Mains; DIY CC; Sunosub I + II + III; DVDs; LDs
     
  2. Scott Simonian

    Scott Simonian Screenwriter

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    Well, its coming in better than we should think. Keep it coming anyway.
    Whenever I get the money, Im hoping I can build new loudspeakers that will possibly be 2 1/2 way also. So I will be using your VERY informative schmatics when you finish it.
    ------------------
    Yes, these are bruises from fighting. Yes, I am comfortable with that. I am enlightened.
     
  3. Patrick Sun

    Patrick Sun Moderator
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    Here's a purtier FR graph plot of the final XO with Adire's nifty ResGraph:
    Graph 1 .
    The orange line is the 1.0 midwoofer response.
    The red line is the 0.5 midwoofer response.
    The yellow (overlapped by dark green below 1.6KHz) is the combined midwoofers response.
    The light green line is the tweeter response.
    The dark green line is the overall response.
    With its logrithmic scale, the graph shows the slope of the 0.5 midwoofer roll-off (starts around 200Hz), and contribute very little above 700Hz. What's weird is that I'm using a 2nd order electrical filter, but the roll-off looks to be an acoustical 6dB/octave slope. Hmm...
    But it seems to clean up the bass, so I'm not complaining.
    The main crossover slopes are roughly 24dB/octave, so the 4th order LR filters appear to be working (crossed over around 2.3KHz) as designed.
    Anyhow, this is my version of a 2.5-way in "slow-motion".
    (Yes, nice room-induced hump down in the 90-140Hz range that I have.)
    ------------------
    PatCave; HT Pix; Gear; DIY Mains; DIY CC; Sunosub I + II + III; DVDs; LDs
     
  4. Brian Bunge

    Brian Bunge Producer

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    Pat,
    The real question is: Are you ever going to paint the damn things? [​IMG]
    Brian
     
  5. Patrick Sun

    Patrick Sun Moderator
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