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Re: LOUDSPEAKER CABLE DIFFERENCES

205.188.192.57

Posted by JHD on June 30, 1999 at 16:33:47

In Reply to: LOUDSPEAKER CABLE DIFFERENCES posted by JHD on June 29, 1999 at 16:42:25:

FROM:John Dunlavy (dunlavy@dunlavyaudio.com)
Date: 30 June 1999

Well! I guess my 29 June post on loudspeaker cables really touched some sensitive nerve-ends among those "subjectivists" who seem intent on ignoring the relevance of much that I said.

Perhaps, adding a few more "objective facts" - not "subjective opinions" - will help those interested in the subject of loudspeaker cables to better understand how their measurable properties determine their ability to transmit complex electrical waveforms between the output terminals of a power amp and the input terminals of a typical loudspeaker.

To begin, I will restate what I (and several others) have said in numerous past postings: THERE ARE NO ELECTRICAL PROPERTIES OR AUDIBLE ATTRIBUTES OF LOUDSPEAKER CABLES THAT CANNOT BE IDENTIFIED AND QUANTIFIED BY A COMPETENT, EXPERIENCED ENGINEER HAVING ACCESS TO A COMPLETE SET OF ACCURATE MEASUREMENTS.

Likewise, it is possible to mathematically model the electrical properties of virtually any loudspeaker cable configuration using a combination of network theory and transmissionline theory.

A complete set of accurate measurements of loudspeaker cables, from quality 12 AWG to those costing $10,000/pr (or more) reveal no differences that could be audibly detected if used within a properly-operating audiophile system of the highest quality, using loudspeakers (with a decent input impedance) that exhibit time-coherent performance and a plus/minus 1 dB on axis "frequency response".

Those who say that it is easy to discern audible differences between a 20 ft. length of quality-made 12 AWG Zip Cord (made by MONSTER) and the same length of an expensive cable such as the MONSTER M-1.5 should know that the accurately measured differences between the two cables are very small across the entire audio range. For example, 12-AWG ZIP cord exhibits a "series impedance" of only 0.58 Ohms at 20 kHz with a phase angle of about plus 70 deg., compared to 0.2 Ohms and a phase angle of about 65 deg. for the Monster 1.5. Used with a loudspeaker having a typical input impedance of 5-10 Ohms at 20 kHz, the difference in amplitude at 20 kHz between the to cables could hardly be considered audible, being less than about 0.64 dB. At frequencies below about 10 kHz, the differences between the two cables with respect to "signal loss" with a lowerspeaker having an input impedance of at least 4-6 Ohms becomes less than about 0,2 dB.

Since both cables use quality dielectric materials with a loss-tangent and dielectric-absorption that does not measurably vary with frequency across the audio spectrum, none of their electrical properties it cannot be expected to create any frequency-dispersiveness that could possibly audibly smear any known kind of musical transient, etc.

So, friends, tell me how high quality loudspeaker cables, including Belden 12-AWG zip-cord, can audibly alter the quality of sound radiated by any properly designed, accurate loudspeaker?

Some audiophiles may claim that there may be some electrical attributes of loudspeaker cables that present laboratory instruments are incapable of measuring. Balderdash! Our own lab at DAL is equipped to measure ALL attributes of loudspeaker cables from D.C. to over 1 GHz (slightly wider than the audio range- heh).

Others may claim that there might be electrical, material (or other) properties/attributes of loudspeaker cables that are audible but have yet to be identified, measured, etc.. Hmmm! Prove there is one and I can almost guarantee a nomination for the next Nobel Prize for Physics.

With respect to "blind Vs non-blind listening comparisons" between loudspeaker cables, is it not strange that those who hear audible differences can only do so when they know which cable is being heard at all times. If no "biases" exist, why can they only hear differences when are aware of the cable being heard? How about a "quasi-blind" comparison protocol, where the listener knows which cable is being heard during the first few minutes but at some "secret time", the cables appear to be switched but are not? If the listener performing the comparison is unaware of the ruse, how can stress build up that prevents further identification? This is one of several, no-stress protocols, we employ at DAL in researcing possible audible differences between cables.

One comment on the FORUM questioned whether our loudspeakers exhibited sufficient accuracy, especially compared to an electrostatic speaker like the ESL-63, to permit listener to detect audible differences between different loudspeaker cables? Yup! DAL loudspeakers have no peer in the market place (regardless of price or manufacturer) with respect to well-documented accuracy. Indeed, the DAL models we use in listening for differences between cables exhibit a plus/minus 1 dB amplitude response Vs frequency, near perfect impulse and step responses, a waterfall response to "kill for", ultra-low levels of non-linear distortion at SPL's up to about 95 dB/1meter, an input impedance that varies from a low of 3 Ohms to a maximum of about 8 Ohms (almost entirely resistive), etc. And those who commented that perhaps the lower accuracy our loudspeakers compared to "membrane types", such as the QUAD ESL-63, have never seen a complete set of accurate measurements for such speakers. (Membrane loudspeakers do not exhibit the level of accuracy most audiophiles believe they possess.)

Anyway, lets continue our exploration of the subject of loudspeaker cables - but attempt to make sure that we have credible facts at hand before we make statements that cannot be verified by competent means.

Best of listening, John Dunlavy

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