jdm56 Posted April 25, 2001 Share Posted April 25, 2001 I know that some of you guys use a full range center speaker with two-channel systems, driven with a summed left plus right signal. I am curious about your experience with this type of set-up with regards to overall bass output. Did the addition of the center smooth or increase total output below 100hz or so? My k-horns in my music room suffer from deep response notches at approximately 50hz and 80 hz. This is observed at the listening position of choice. The only way to smooth it out is to sit right against the back wall, but this is too far from the horns axis, which just destroys lateral imaging. So, last night I was experimenting with the addition of a small subwoofer in the spot on the front wall where I hope to eventually install a belle klipsch or a cornwall center. And low and behold if that little sub didn't come on strong exactly where the cornerhorns are weak! Their output was strong at 50 and 80 hertz, but was down at 40, 100 and 125 hertz where the cornerhorns are strong. After I positioned the sub directly in front of the right k-horn, I remeasured and it's response was very similar to the big horns except for being way down in overall sensitivity, of course. All this has me thinking a center channel belle will actually smooth my systems bass output PLUS add the center fill to my "long wall" set-up that was my reason for wanting it in the first place! I'd appreciate hearing about anyones experience along these lines. ------------------ JDMcCall Quote Link to comment Share on other sites More sharing options...
JohnA Posted April 26, 2001 Share Posted April 26, 2001 That 50 to 80 Hz notch is a characteristic if the K-horn. You may not be able to eliminate it. I have seen it in at least 2 graphs of the K-horn's response, but it was not in the 3rd. John Quote Link to comment Share on other sites More sharing options...
jdm56 Posted April 26, 2001 Author Share Posted April 26, 2001 John, Surely notches this deep aren't typical. I'm talkin' 18dB down at 50hz; 12dB down at 80hz. Response at 31.5, 40, 63 and 100hz on up is pretty normal for k-horns, I believe. And yet, if I measure close to the back wall, response smoothes out while overall bass level comes up. Which would be great except for the lousy imaging from there. I'm really hoping the addition of a full range center will help. And as soon as I win the lottery, maybe one or two of those new Klipsch Reference subs! Actually, didn't PWK recommend that the ideal listening room for klipschorns would include a sweet spot against the rear wall? Maybe I should get the hammer and saw out and go to work... ------------------ JDMcCall Quote Link to comment Share on other sites More sharing options...
JohnA Posted April 27, 2001 Share Posted April 27, 2001 The notch I saw was not THAT deep. It was 5 or 6 dB max. I don't remember a suggested sweet spot at the rear wall. John Quote Link to comment Share on other sites More sharing options...
jdm56 Posted April 27, 2001 Author Share Posted April 27, 2001 John, After much moving and measuring, I settled (for now) on a listening spot a little closer to the back wall, but not enough to ruin imaging. Here, the 50 and 80hz notches measure a somewhat more tolerable 12 and 8dB down from the midrange level, respectively. It's amazing how small differences in the location of spl meter generate big measurement differences. I wonder how accurate those things really are anyway. Sometimes the measured change from one test frequency to the next don't seem to match what my ears tell me. Also, when moving the sub around, I was surprised at how great a change was displayed even by variations of less than a foot in sub placement. I don't recall; do you use a center channel with your la scalas for stereo? -JDM Quote Link to comment Share on other sites More sharing options...
djk Posted April 28, 2001 Share Posted April 28, 2001 Figure 9 in the JAES Vol. 48 No. 10 shows the Pi/2 anechoic response of a Klipschorn to have a narrow 5dB dip at 75hz and be flat at 50hz. I suspect your room is 14' X 22.5' Quote Link to comment Share on other sites More sharing options...
jdm56 Posted April 28, 2001 Author Share Posted April 28, 2001 djk, No, my music room is 18.5 X 16 X 8.67, with the speakers on the long wall. When I was trying to come up with dimensions for it, my main concern was not to have pile-ups of room modes. And I was successful, but maybe too successful. A little bit of knowledge can be a dangerous thing. Because I apparently have come up with dimensions that are not conducive to smooth klipschorn bas below 100hz. It's pretty good at 40 and 63hz, but down at 50 and 80hz. I've measured two speakers and one subwoofer at the corner location and all three were down at 50 and 80 hz, but not as severely as the 'horns. I assume because they are more "in the corner" than the other two. (The other two were placed directly in front of the right 'horn. After all this measuring and comparing, I'm convinced that a belle or a cornwall in the middle would solve the bass problem (at least, down to 40 hz). Now if I could just find a belle or a cornwall! Preferably a belle because of the overall higher sensitivity, which matches the cornerhorns. I guess klipschorns are even more sensitive to room dimensions than I realized. I always thought as long as you had good corners, you were 90% there. But if you stop and think about how "normal" speakers bass performance is affected by even small changes in placement or listening spot, and that with cornerhorns, you are so much more limited in those areas, I guess it should not be so surprising. You are more or less at the mercy of the room. ------------------ JDMcCall Quote Link to comment Share on other sites More sharing options...
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