Good Bets, Possibilities, & Improbables
Some of this is backed by sufficient evidence, forrnal or otherwise, that it must be accepted as Probable Truth. Some is almost certainly rubbish, worthy of note only by mystics and charlatans who would use mysticism to promote their audio image. In the middle is a wide range of what can be considered questionable doctrine, embraced by some and scorned by others.
Much of this audio legend has to do with the audibility of certain system parameters. This is probably the grayest area of them all, because the audibility (or otherwise) of something depends so much on so many things: the "normalcy" of the listener's aural equipment, the depth of his listening experience, the kind of program material, his familiarity with the system on which he is listening, and the capability of that system for revealing small sonic differences.
None of these factors can be formalized, because some listeners can hear certain small differences through truly rotten systems while others cannot hear larger differences through highly revealing systems. To further confound the issue, some people are congenitally "deaf" to certain aspects of reproduced sound, while others claim to be able to hear things which no one else apparently can. Since there is an absolutely amazing lack of scientific corroboration for such claims of audio clairvoyance, the best we can do is hold them up against what we feel we do know about the objective world around us, and see how well they agree with that knowledge. This approach cannot eliminate erroneous conclusions, but it does reduce the likelihood of error.
I am in no position to pass definitive judgment on these claims (I don't even know where I stand on ESP), but I am perfectly willing to stick my neck out by categorizing them according to their intellectual respectability. Herewith:
(A "good bet" is something for which the evidence is so overwhelming that it might as well be accepted as Truth until proven otherwise. The following, I feel, belong in that category.)
"Cables are audible."
Although still not accepted by many "experts," this has too much evidence supporting it to be ignored.
Very high values of capacitance, inductance, and dielectric absorption cause signal degradation which is not only audible to most people but is also easily measured. A truly bad speaker cable will cause many amplifiers to oscillate. A high-capacitance audio cable will cause HF rolloff well within the audio range. Both are clearly audible. It is only the audibility threshold of these things which remains in doubt.
"Turntable mats are audible."
Not to all listeners, but certainly to many. Again, extreme cases of uncontrolled disc vibration are hard to miss, but the threshold of audibility varies so widely it is impossible to pin down. But then, see the section on IT mats and platters under "Improbables."
"The earlier the amplifying stage, the more audible the distortion."
Each amplifying stage in an active device adds some signal distortion, and each stage compounds the distortion being fed to it. Thus, 0.1% harmonic distortion in an output stage is far less detrimental to the sound than 0.1 % in the first phono preamp stage.
"Tubes sound better than solid-state."
Most listeners who relate to live, acoustical music agree that this is nearly always true at the high end, where a tube's distortion characteristics sound more "musical," or "euphonious" if you will.
"Solid-state is better than tubes."
Nearly always true at the low end, where the lack of an output transformer allows transistors to feed more power at a higher damping factor to the woofer, exerting more control over its cone motion.
"Acoustic feedback is inversely related to available power."
Higher amplifier power, exercIsIng better control over the woofers, reduces the tendency for woofer resonances to induce acoustic feedback in the system.
"Moving-coil cartridges have better transient response than moving-magnet cartridges."
Without a doubt objectively true, subjectively almost certainly true.
"New discs sound better after wet-cleaning."
This too is supported by objective evidence. Many discs come from the stamper with a thin coating of a waxy material that is added to vinyl to prevent it from adhering to the stamper. Removing it usually improves the sound.
"Analog tape smears transient response."
Analog tape causes an increasing time delay at increasing frequencies, rounding off sharp attacks. Objectively proven and subjectively corroborated. (The effect diminishes at higher tape speeds.)
"A tape copied backwards has better transient response than the original Master."
Proven true. See preceding item. Reverse copying tends to restore the original time alignment.
"Elliptical styli wear discs more rapidly than do sphericals."
Generally true. In theory, a line-contact stylus yields less wear than a spherical; in practice (ie, when vertical alignment is not perfect) it usually produces more. Normal ellipticals, at a given tracking force, wear discs faster than sphericals because the former's contact area is smaller, producing higher contact pressure per unit of area.
"Different capacitors sound different in audio circuits."
Again, not formally proven, but the weight of informal evidence indicates that this is true.
"Phase-Coherence (time alignment) in loudspeakers improves their sound."
Although never conclusively proven, evidence in support of this is far more plentiful than evidence countering it.
"Inaudible noise can affect reproduced sound."
Yes and no. Normally audible noise such as hum and hiss do not seem to affect sound when reduced to inaudibility themselves. But indications are that the presence in a system of normally inaudible "noise" such as RF interference can degrade the detail and clarity of the sound. Not proven, though.
"Absolute phase reversal (signal polarity) is audible."
Certain nonlinearities in loudspeakers can make polarity reversal audible to virtually everyone. In the absence of these, some listeners seem to be polarity-responsive while others are not. Which is "normal" for human hearing will only be ascertained when someone tests a large sample of the total population for polarity responsiveness.
Among those who claim to have the ability, none has ever demonstrated a correlation between observed correct polarity ("this way sounds the best") and what is in fact the original polarity. The original polarity of a signal is difficult to determine since almost every amplifying stage from microphone to cutter head inverts the phasean even number of reversals maintains original polarity, an odd number inverts it. These data are not published with the record.
"Phase shift is audible."
Neither proven nor disproven, this is one of the iffier propositions of audiophilia. Indications are that it is, under certain cQnditions, and is not under others.
"Copper wire sounds different from silver wire."
There is some evidence that, assuming all other phy sical parameters to be the same, different conductor materials do sound different, and increasingly so as the wires are lengthened. There is far less evidence of any audible difference where very short wire lengths are involved.