On Wed, 11 Jan 2006 20:54:11 -0000, "Paul B" wrote:
Thus spake Don Pearce:
OK, I've had a bit of a think - and I've written a protocol, which I
believe would be a basis of fair testing of audio components to
resolve such issues as cable sound etc.
I invite all here to read what I suggest, and let me know if I have
either missed something, or am being unfair on one direction or
another.
http://www.donepearce.plus.com/odds/dbt/
I think this could be a way of defusing the vituperation that
currently surrounds the subject.
So what do you think?
d
Pearce Consulting
http://www.pearce.uk.com
This subject, for good or bad, really fascinates me but I'm sceptical that
anyone would score that much over 50%. The reason I suggest that has little
to do with what I happen to believe (well, I hope that but anyone
proclaiming their own impartiality often isn't) but due to the nature of our
hearing skills (for want of a better phrase) would mask anything but huge
differences that could be easily measured. The glaring problem is memory - a
somewhat arbitory concept & very subjective. Sorry, but I can envisage, in
theory, that differences between cables is provable as opposed to being
non-existent. An alternative view might be that differences between cables
are indeed real but are swamped by differences due to alcohol consumption,
level of wakefulness, medical conditions, mood etc to the point of
diminishing returns. I'm suggesting that there are huge differences to our
auditory perception without throwing cables into the mix!
There's obviously no harm in people running their own informal tests with
some friends but to draw any conclusions from scientific & statistically
valid tests, /would/ cost a fair penny & would possibly run over a long
period of time. Part of the testing may need to calibrate a threshold where
differences /can/ be heard using differences of volume, changing resistance,
capacitance, inductance, group delay frequency response, amplitude
compression etc. If subjects prove inept at hearing these *real*
differences, I feel the testing methodology of DBT as postulated was
inappropriate. I haven't researched the subject enough to know how much is
already known but was curious to know how for instance, anyone could
determine the average frequency response of the human ear but it has been
done. IIRC, a single fixed tone is alternated with a stepped tone then
repeated probably thousands of times over many subjects who have to judge
loudness. Someone must have also conducted many psycho-acoustic tests on
lossy compression formats where the results were largely subjective, so it
might be indeed possible but only if great care is taken.
So what other methods can one use apart from sequential stop start tests? AB
comparison test validity could be improved even if switch noise was present
by randomising the order, eg A B A A B A B B A to lessen the auditory memory
uncertainty.
I presume that the test cables would need to be characterised regarding
their F, H & R but how - just at spot frequencies? To widen the subject
slightly to include specifications such as distortion, is the harmonic
content of one frequency (often 1KHz into a resistive load) telling us much?
Do even swept measurements give any idea how "good" an amplifier will sound.
It is theoretically possible that these differences are real but the tests
are inadequate - heresy to some. However, we are discussing cables here
only.
I hate auditioning new stuff & would love to be able to select equipment on
specification, looks, build quality, ergonomics, power consumption, price
etc.
I don't presume to be an expert, so several points I've made may well have
many weaknesses but any tests done without much thought would just
perpetuate the schism.
Interesting stuff, but sort of wide of the point. The purpose of the
protocol I have published is not to establish whether it is possible
to hear differences between cables. It is to confirm whether
differences that have been identified as readily audible are genuine
or imagined; that is a very different thing.
The measurements are designed to establish basic levels of competence
for the cables to make sure that they do not exhibit gross frequency
response differences that would be audible, masking the subtle "magic"
effects claimed by the boutique cable houses.
As for auditioning new equipment - would you really bother apart from
speakers? Anything else you buy on looks and features.
d
Pearce Consulting
http://www.pearce.uk.com