I 've just started recording with my new Portadisc and am very pleased with
it. I had been loath to move from DAT because in spite of all the postings
in favour of MD I still had a niggling fear that the quality might not be
as good as DAT.
Walter posted a detailed blind comparison of MD v. CD a year or two ago,
which showed no audible difference, but since then a few people have again
raised doubts as to a possible loss of audio quality due to MD's ATRAC
'compression' . On their web site Cornell write 'recent claims that Sony's
ATRAC 3.5 & 4.5 coding versions are considered by some professionals to be
indistinguishable from, or even better than a CD remains to be proven.' I
thought that as I have both types of recorder I would make a
small contribution towards resolving the question.
I connected a Sennheiser ME62 in a Telinga reflector to both a Sony
TCD-D10PROII (R-DAT) and the Portadisc (MD) and then recorded the song of a
Yellow-legged Thrush simultaneously on both recorders. Doug has posted two
files on http://www.naturesongs.com/recordists/nrfiles.html , MDtest1 and
MDtest2, which are excerpts from this recording. The only processing these
files underwent was that I adjusted the amplitude of each by equal and
opposite amounts so that their volume sounded about the same and converted
the R-DAT file from 48000 to 41000 samples/sec so that I could show the
recordings side by side. Each file consists of the same bit of the song,
first as recorded by one recorder and then by the other. The order was
decided by spinning a coin.
I'd be interested to know whether you can spot which is which by ear. If
you look at the spectograms, however, it becomes fairly obvious, ATRAC
having discarded part of the signal, but I think you'll agree that
difference between the main features of the spectograms is insignificant. I
would like to quote to you a 1999 posting to NEOORN by Morton e Phyllis
Isler, well known ornithologists working at the Smithsonian, which puts the
matter very clearly:
"About a year and a half ago, NEOORN had an excellent back and forth
discussion about Minidisks, but a number of you may not have been enrolled
at that time, and Charles Duncan's quote from the Budney [curator of
Macaulay Library of Natural Sounds] and Grotke [MLNS audio engineer] paper
belittling Minidiscs requires a renewed response.
The key question is whether audio engineer Grotke's conclusions about
deficiencies in the Minidisk are relevant to its application to recording
and using avian vocalizations. Our conclusion, after years of using
Minidiscs, is that his conclusions are not relevant. We have also put
Nagra, cassette, and DAT recordings directly into CANARY (the Cornell
Bioacoustics Workstation) and compared these with the same recordings put
onto Minidisks and then into CANARY. We have seen no differences in the
displays (e.g. spectrograms) and because we measure vocal characteristics
from displays, we can see no difference in vocal measurements that we
take. We have never found the slightest evidence of sound distortion
caused by the MD."
That sums it up.
The main song in each file is by a male Yellow-legged Thrush. In MDtest1 a
Rufous-bellied Thrush calls in the background. In MDtest2 there is a
distant call by ( I think) a Tropical Kingbird near the beginning and a
Southern House-Wren calls and then sings at the end. The noise in the
background is the South Atlantic, not an expressway.
Personally I'm entirely satisfied with MD.
Jeremy
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