maxdimario wrote on Mon, 28 November 2005 12:37 |
some things I am pretty sure about consistently.
consider I've been listening for the same things now for 15-20 years, so it might take me a minute, but I am pretty sure.
I used to kill myself for weeks trying to decide between one variable in a circuit and another, going back and forth.. trying to decide.
the senses can develop if one is nuts enough (dedicated?) to focus in.
the only exception being in extreme states of stress.. then I do find I lose my hearing... or after very loud sounds..
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The ear can easily tell you the difference between musical notes (pitch) and some people can be trained to have absolute hearing. Mother nature intended us to respond to volume, pitch and much more of the content we find in air vibrations we call sound.
But going back and forth between say some electrolytic cap and a polyester, in a circuit made out of hundreds of parts (variables) is better left for test gear first, ear last.
True, a certain part that seem to perform very well (or poorly)in dozens of different applications and designs, is worth looking into. But more often then not, people come to a hasty conclusion based on limited understanding (or no understanding at all).
I have come across statements about OPamps (amplifiers), such as XXX is great (or YYY sounds bad). Say XXX could have been tested as inverting amp (where input common mode is a non issue), or XXX was tested with clean power supply rails (though it has a poor power supply rejection), or XXX load is very high... The same OPamp could be could bad news in a different circuit, such as non inverting (common mode problems), noisy and unsteady supply, heavy load... There are "endless" combinations out there.
Another set of example would be caps. Some came to believe in "no electrolytics in the signal path", a statement that can be very true or very false, depending on circuit architecture.
A statment that claims "no electrolytics in the signal path is a good thing" is clear indication for one's lack of understanding of circuit design!
Some prefer poly caps everywhere, which is silly, given that polycarbonate is very different then polypropleyne, that polyester has it strong points, that some applications call for ceramics, tantalum, aluminum...
I have come across many statments about caps, resistors, transistors, wires... many of them are based on ironoius conclusions based on listening. The listeners were of course honest and serious, but the lack of understanding for the physical reasons that cause the observations, can lead to wrong generalizations.
Another way to put it - The voltmeter is the wrong tool to tell you about pitch, the ear is the wrong tool to tell you about voltage...
The ear can be trained to do many things (all sound related). The ear can tell you what sounds right, what it likes (or does not) and so on. The ear can not tell you that something sounds better because there is some 50KHz audio content in the air. The ear is not trained to hear 50KHz, in fact it can not react to 50KHz.
Last comment - there is too much emphasis regarding the importance of filters in how converters sound. Filters are important, but can be be designed well. There are other issues I consider much more important, from the basic approach to many circuit details.
Regards
Dan Lavry
www.lavryengineering.com