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High Frequency Compression Driver Evaluation
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<blockquote data-quote="Art Welter" data-source="post: 51541" data-attributes="member: 52"><p>Re: High Frequency Compression Driver Evaluation</p><p></p><p></p><p></p><p>You are correct, Gunness focusing addresses four problems, distortion is not one of the correctable problems:</p><p>1) All phase plug designs produce significant smearing of the transient response. </p><p>A significant fraction of the sound energy arriving at a phase plug opening will either continue past it or reflect back from it; in either case arriving later at other phase plug slots where the sound is divided again, ad infinitum. </p><p>A carefully constructed filter falls short of perfectly correcting the axial response, but it improves it significantly, while also significantly improving the off axis response. </p><p></p><p>2) A second loudspeaker behavior, which yields well to digital preconditioning, is horn resonance. </p><p></p><p>3) A third behavior, which also yields to digital preconditioning, is cone resonance. </p><p></p><p>4) A fourth behavior is non-linear phase response of the summed crossover.</p><p>The essence of the ilter to correct that defect is the high frequencies are delayed relative to the low frequencies, which counteracts the minimum phase crossover’s effect of delaying the low frequencies relative to the highs. This requires an added high frequency latency of .7 ms, the full length of the FIR filter. A nearly perfect approximation can be achieved with 1 ms or more. </p><p></p><p></p><p>All four combined can indeed make a speaker sound much better.</p><p></p><p>My driver comparison focused on the uncorrectable problem of distortion.</p><p></p><p>Uncorrectable, as evidenced by an older driver design developed more than two decades ago while Dave Gunness was still working for Electro- Voice having less distortion than more current designs.</p><p></p><p>The distortion inherent in HF compression drivers is a tough nut to crack.</p><p></p><p>The lack of progress in reducing distortion may be why Bennett, who is usually quite prompt, has not responded to my requests for further distortion information from B&C in post #7.</p><p></p><p>Art</p></blockquote><p></p>
[QUOTE="Art Welter, post: 51541, member: 52"] Re: High Frequency Compression Driver Evaluation You are correct, Gunness focusing addresses four problems, distortion is not one of the correctable problems: 1) All phase plug designs produce significant smearing of the transient response. A significant fraction of the sound energy arriving at a phase plug opening will either continue past it or reflect back from it; in either case arriving later at other phase plug slots where the sound is divided again, ad infinitum. A carefully constructed filter falls short of perfectly correcting the axial response, but it improves it significantly, while also significantly improving the off axis response. 2) A second loudspeaker behavior, which yields well to digital preconditioning, is horn resonance. 3) A third behavior, which also yields to digital preconditioning, is cone resonance. 4) A fourth behavior is non-linear phase response of the summed crossover. The essence of the ilter to correct that defect is the high frequencies are delayed relative to the low frequencies, which counteracts the minimum phase crossover’s effect of delaying the low frequencies relative to the highs. This requires an added high frequency latency of .7 ms, the full length of the FIR filter. A nearly perfect approximation can be achieved with 1 ms or more. All four combined can indeed make a speaker sound much better. My driver comparison focused on the uncorrectable problem of distortion. Uncorrectable, as evidenced by an older driver design developed more than two decades ago while Dave Gunness was still working for Electro- Voice having less distortion than more current designs. The distortion inherent in HF compression drivers is a tough nut to crack. The lack of progress in reducing distortion may be why Bennett, who is usually quite prompt, has not responded to my requests for further distortion information from B&C in post #7. Art [/QUOTE]
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