Duke Spinner Posted December 26, 2005 Share Posted December 26, 2005 its been 30 years since i thought about crossover stuff ... at 12dB/ octave .... isn't half the energy above ... 'n half below ... the center freq ...??? Quote Link to comment Share on other sites More sharing options...
djk Posted December 26, 2005 Share Posted December 26, 2005 The Altec chart is misleading at best. Those are the recommended crossover frequencies, not the horn Fc. As stated by PWK in the AU-11 issue of the IEEE(Nov-Dec, 1963), the Fc of the K5J was 300hz, and the Fc of the K400 was 240hz. The taper rate of the JBL/Altec horns designed for 300hz crossover was typically 190hz, about 1/2 octave lower than the intended crossover point. A full octave would have been better from a response smoothness standpoint, but would have increased the bulk by a factor of 8(2^3), and increased HF distortion as well. If a horn was flat to its Fc(which it is not), then generally speaking, for a 1dB error in the sum of the woofer output plus the HF output, you need: Two octaves for 6dB One octave for 12dB about 1/2 octave for 18dB or 24dB A K400 with the K55V drops about 10dB from its Fc of 240hz to 200hz(1/3 octave), and is down about 20dB at 200hz WRT 400hz. All without a crossover. Introduction of a simple 6dB filter (A or AA network), gives a very complex acoustic transfer function steeper than 24dB/oct. Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted December 26, 2005 Share Posted December 26, 2005 Cool ......now, that's an answer Thanks , DJK ...[] Quote Link to comment Share on other sites More sharing options...
sunnysal Posted December 27, 2005 Share Posted December 27, 2005 yup thanks, yet another post I will print out and save. tony Quote Link to comment Share on other sites More sharing options...
D-MAN Posted December 28, 2005 Share Posted December 28, 2005 If you cross a 400Hz horn at 500Hz -- does it still load properly? I do it everytime I listen to my system! I crossed at 600Hz in a 400Hz horn! DM Quote Link to comment Share on other sites More sharing options...
raypenn Posted December 28, 2005 Share Posted December 28, 2005 Dean - Do you think that you would hear much difference if you crossed at 500 or 700? Thanks. Quote Link to comment Share on other sites More sharing options...
travisc Posted December 28, 2005 Share Posted December 28, 2005 Dean - Do you think that you would hear much difference if you crossed at 500 or 700? Thanks. I changed from 600hz to 400hz today with a 511b and there is a huge difference in male vocals. though I am still confused. type B is a 6dB slope correct? 6dB less per octave(bear with me I am learning) Quote Link to comment Share on other sites More sharing options...
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