On 08/04/2010 16:29, Jim Lesurf wrote:
In , Rob
wrote:
On 08/04/2010 12:45, Arny Krueger wrote:


Rule number one is that when you do comparisons like this, you take
the high sample rate file and downsample it yourself, which is easy to
do with free software that can downloaded from the web.


Why's that - are Naim not to be trusted?

Erm... I've not checked, but I presume they are making the files available
for people to listen to rather than use as examples for assessing the
effect of *only* changing the sample rate and/or bit-depth.

Not sure what "trust" has to do with that *unless* Naim have stated that
the *only change* was to downsample one version. Even then I'd personally
want to know the details of the process to be able to understand what
effect that may or may not have.


See below, and I was just wondering if there's any convention here with
the offer of two sample rates, where any difference is contestable
(unlike mp3s, where most people acknowledge a difference).

However I would "trust" then to do their best to make good sounding
versions if their purpose is to produce material people want to listen to.
Without other evidence, though, I don't know what they'd think the best way
to do that. So don't know what they would do to make versions at different
sample rates, etc.

When doing such things on a scientific/academic basis you want to know all
the details as they may affect the results for reasons that differ from the
assumptions that otherwise might be made.

The context in such terms is that I think others have already found that
some dual format commercial releases show things like differences in level
compression, made because those producing the versions assumed something
different was 'better' for the different (assumed) target audiences for the
two versions.

There are also various choices that could be made when using one version to
create the other, that then vary the output. e.g. I understand that at one
time Tony Faulkner preferred a simplistic form of downsampling that doesn't
actually meet the sampling theorem. He preferred the results, presumably
because he thought it made a 'change' that he liked. Or because it
minimised in-band filtering at the expense of aliasing.


That's really why I ask - I think. If there's more than one way to
downsample properly, I'm stuffed.