[Arny Krueger]

"Doug McDonald" wrote in
message
Sonnova wrote:


Yep. When making any kind of sonic evaluation, one must
be careful to match all levels exactly. If one device
under test is even subliminally louder than another,
that's the one that the ear will favor as being the
better of the devices under evaluation. This holds true
for signal sources, amplifiying devices as well as
speakers.

I simply do not understand this. Why should exact level
make any difference in tests of quality.

Because differences in level are very easy to confuse with differences in
sonic quality.

Sure, if you are trying to tell if you can tell ANY difference between
systems, it matters ...

Small differences in level often don't sound like simple differences in
loudness. They can make many people think they are hearing differences in
timbre, resolution, graininess, etc.

you could have two absolutely identical systems, that
were indistinguishable if level matched, and if they were off by 0.5 dB
anybody could tell them
apart.

Often but not always.

But it would be impossible to tell
whch was "better" since they would be the same.

Well, if they sound the same, what's wrong with that?

I've tried such tests, and indeed it is impossible to tell which is
better even if not level matched.

It is very rare in general for people to hear differences and not decide
that one is "better".

Approximate level matching might also be important
if two systems differed only in frequency response (in
which case, of course, exact level matching would be impossible,

If you have two systems that differ in loudness to an audible degree, how do
you know that there is actually another other difference, especially if that
difference is subtle?

for all frequency bands!) But if two system actually had
other differences (distortion) it should be noticed even
if the levels were only approximately matched.

Distortion will cause systems that are level-matched at low levels to have
mismatched levels when played much louder.

I've tried such tests too, and the level matching did not matter.

I don't know why there would be any angst over level-matching. It is
generally easy enough to do. If it can't be done because there are
significant frequency response differences or distortion, then those are a
very valuable things to know.