On Thu, 6 Jan 2005 16:55:31 -0000, "Richard Wall"
wrote:


"Don Pearce" wrote in message
...
On Thu, 6 Jan 2005 11:04:55 -0000, "Richard Wall"
wrote:

Can anyone point to a Hi-Fi DBT test where no changes were actually made
in
the source material to check that the audience could perceive no change ?

That would be EVERY DBT test. Each sample is randomly selected from
the two possibilities - that means that in each test the source has
either changed or not. So false positives and false negatives both
show up as failures, and this is as it should be.

I think the reason you have problems with DBTs is not that they fail,
but that they pretty much always succeed. They succeed in showing that
there is in fact no sonic difference between the components under
test. Again, these days that is as it should be - we have advanced far
enough along the HI Fi road that pretty much all components should
sound the same.
Why do you think they always suceed ? I would have thought that most
manufacturers would work to make their systems sound different and the vast
array of suppliers would surely not exist if they all sounded the same ? It
should easily be possible to take three similar amplifiers, modify their
frequency response at above the limit of hearing a difference and then get a
conclusive proof of the effectiveness of the testing method. Has it been
done ?
It may be easy enough to make all kit sound the same, but as it is unlikely
that even if they did all make the prefect reproduction equipment, everyone
would prefer it. I think all the systems belonging to members in our club
sound quite distinct, it would however be impossible to test this opininion.
You have also missed my point that although the testing method is proven the
results on Hi-Fi are not. Hearing is not an absolute and will change over
the listening period. Trying to listen for differences is not the same as
listening to appreciate music. Unless you have data to prove otherwise the
sample sets used to evaluate Hi-Fi are small so surely with false positives,
false negatives and perception changes is it any wonder that the statistics
say that most things cannot be differentiated.

d


Hi Fi manufacturers are the same as any. They change things for two
purposes. First is to make them cheaper to improve the margins. Second
is to make them appear different so that not only new buyers but old
ones will purchase the new item.

There is of course absolutely no need to make them sound different -
actual improvement ceased long ago - while one-upmanship and other
psychological effects do such a fine job without effort on the part of
the manufacturer.

The one area where none of the above applies is the loudspeaker, which
is still frankly a disgrace. You don't need a DBT to reveal the
differences between speakers, and unlike the other stuff, the
differences persist under DBT conditions.

As for DBTs usually succeeding - it is simply true. It is very easy to
run a good DBT. But maybe my definition of success is not the same as
yours. Mine is that the DBT reveals the truth, whatever that is. Maybe
you consider a DBT to have failed if it does not show a difference?
That would be a reasonable conclusion to your assertion that DBTs
don't work for Hi Fi. If things cannot be differentiated in DBT, it is
because they actually aren't different.

d

Pearce Consulting
http://www.pearce.uk.com