Andy W Posted July 5, 2002 Share Posted July 5, 2002 PWK had this to say: "Modulation distortion is proprtional to the amplitude of motion of the driving diaphragm. Frequency modulation distortion (FMD) resulting from the Doppler effect is dirctly proportional to the amplitude of diaphragm motion. Amplitude modulation distortion is approximately proportional to amplitude of motion. Total modulation distortion (TMD) is the sum of these two forms of modulation distortion. "AMD tends to dominate in direct radiator loudspeakers, and FMD tends to predominate in horn type loudspeakers. The ratio of TMD to total output is lowest in horns, intermediate in ported-box direct radiator loudspeakers, and highest in total enclosures." ©1976 IEEE, Inc. _Loudspeaker Distortion_ by Paul W. Klipsch I will note that because he said FMD dominates a horn's TMD does not mean a horn's FMD is worse than a direct radiator's FMD. The article goes on to show data from the three aforementioned speaker types: closed box 12" @ 100dB SPL -- f1=42Hz, f2=350Hz, TMD=8% ported box 15" -- TMD=0.8% horn 15" -- TMD=0.3% Regarding the power cable stuff: If you can't measure this "pshycoacoustic" stuff how does an engineer design a power cable that elimiates it? Where does he/she begin? What electronic theory does he apply to get rid of the phenomenon? How does he know if he succeeded? A listening test? Is the background "blacker"? What is blacker sound? A lower noise floor? I can measure a lower noise floor. This power cable purpotedly reduces EMI. Ok fine. Can EMI produce audible artifacts? You bet. Can you design a power cord to filter EMI? Sure. Can you measure lower EMI? Yup. So I ask, what is this unmeasureable entity that you can hear, but an Audio Precision can't? Mr. Golden Ears Equipment Reveiwer can supposedly hear something the AP can't measure between a $1,000 amplifier and a $10,000 with identical specs. And a power cable can produce an audible benefit to the $10,000 amp that can't be detected when used on a $1,000 amp because "high-end equipment can benefit from this type of upgrade, while the shortcomings of the $1,000 amp mask the psychoacoustic phenomenon in question." How loud does a psychoacoustic phenomenon have to be in order to mask another one? 20dB? 40? And you have to spend another $9,000 to remove the one in order to hear the other? Then I have to buy $1000 speaker cables to reveal another layer of murk that only a $1150 power cable can remove? At this point I have to agree with PWK -- "Reviewers of equipment who report 0.01% amplitude modulation distortion in amplifiers and ignore 10% or more amplitude and frequency modulation distortion in loudspeakers might well revise their prejudices." If I'm buying a $10,000 amplifier, why didn't the designer add circuitry to remove this line cord induced pshychoacoustic veiling that's 100dB below the distortion level of my favorite loudspeakers? mode>-Andy W (donning flame retardant Jockeys) quote: Originally posted by John Albright: There is one thing a 3-way Klipsch horn-loaded system CANNOT suffer from and it's Doppler distortion. Horn loading and small diaphragm movements prevent it. A 2-way monitor with a 6-inch "woofer" crossed at 2k is the prescription for doppler distortion. Credibility blown. John Quote Link to comment Share on other sites More sharing options...
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