Can chrome tape sound as good as CDs?
Taking the BASF
CD challenge
Over the next few months in shopping malls,
record bars and at major sporting events,
Australians will be challenged to identify whether
music is coming from a BASF chromium dioxide
audio tape or a CD. BASF reckon you won't be able
to hear the difference.
By LEO SIMPSON
Not only do BASF reckon that
their chrome tape is "damn close to
CD" but they also state that their
chrome tape is "99.9% noise-free".
Such claims seem outrageous, don't
they? After all, everyone knows
that CDs and CD players have a
much greater signal to noise ratio
and available dynamic range than
cassette players. CDs also have
lower distortion, better frequency
response and much lower wow and
flutter.
BASF still reckon that few people
will be able to tell the difference
when they listen to the set-up they
will have in shopping malls and
record bars. Essentially, the equipment rack you will see uses standard Pioneer hifi equipment - a
CD player, a 3-head stereo cassette
deck with Dolby C noise reduction
and a stereo amplifier which drives
several sets of headphones.
At the top of the rack is a unit
made by BASF which switches the ·
output signals from the CD player
and the tape deck to the inputs of
the stereo amplifier. It does this in a
random fashion so that you listen to
10 12-second segments of music.
You then have to identify, as you
listen, whether the music is coming
from the CD player or the tape
deck. The tape deck is recording
the signal from the CD player and
the output is taken from its
playback head.
Thus it is quite easy to pick when
the music is switched because there
is a time delay of abuut 0.3 seconds
between the CD signal and the tape
playback signal. Picking the moment when the signal is switched is
no problem at all; picking which is
which is a lot harder.
Most people, after they 've marked the score sheet, get less than five
out of 10 right.
Dolby C noise reduction
When these two Sydney Kings basketballers took the BASF CD Challenge, they
could not tell the difference. Depending on the type of music being played and
the noise level of the surroundings, it can be very difficult. Few people
achieve a score of better than 5 out of 10.
68
SILICON CHIP
The tricky part is the use of Dolby
C noise reduction in the tape deck.
BASF make the point that compact
discs are rarely recorded with a
dynamic range of more than 70dB
and that most hifi cassette decks
with Dolby C can achieve a signalto-noise ratio of 70dB or better.
Hence, as far as signal-to-noise
ratios are concerned, there is less
difference between CDs and cassettes than you might think.
The other trick is in the selection
of the music used for the test. If the
program is classical music, it tends
to be easier to pick the difference
than with most popular vocal recordings which have relatively little
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The other point to be noted is that
the venue where these "CD
challenges" are taken is not the
best for serious music listening.
Shopping malls are notoriously
noisy places so, even when listening
on headphones, trying to pick differences in sound quality is very
difficult. Most people are likely to
conclude that the differences are
non-existent, which is just what
BASF wants them to think.
Is it valid though? With a lot of
recorded music on CDs, the answer
is yes - because it has not been
critically recorded with the very
best sound quality in mind.
However, if the same comparison
is carried out in a quiet room with
good loudspeakers and the very
best that CDs can offer, few hifi enthusiasts with keen hearing will
have any problems picking the difference between CDs and BASF
chrome cassettes simultaneously
recording with Dolby C. If the test
was done using dbx noise reduction, it would be quite a lot more
difficult.
Incidentally, while most hifi
cassette decks these days have both
Dolby B and C noise reduction, most
car players, Walkman-style players
and "ghetto blasters" don't even
have Dolby B.
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The cornerstone of the BASF CD Challenge is the use of Dolby C noise
reduction. These curves show the difference in high frequency noise
attenuation between Dolby B and C. Dolby C can give a signal/noise ratio of
70dB or better.
What is the point?
Why has BASF gone to the trouble of running the CD challenge?
Well, as you might expect, it is a
marketing exercise designed to
draw attention to its new Chrome
Maxima II cassette. This has a
redesigned housing which is claimed to be more rigid and to give better tape azimuth for minimum high
frequency losses. The housing is
also claimed to be less likely to
distort when subjected to the high
temperatures in cars.
At the same time, the tape formulation has been improved to give
a greater dynamic range, which is
where the statement " 99.9% noise
free" comes from. BASF quote a
signal to noise ratio of 60. 5dB
without noise reduction. When you
convert this to a straight ratio, it
gives a figure of .0009441 or as
BASF states, better than 99. 9%
noise free.
What do you think?
~
BASF's new
Chrome Maxima
II uses a high
precision shell
which gives
better tape
azimuth and is
less likely to
distort at high
temperatures. The
tape is a double
layer type with
high coercivity
for greater signal
range.
APRIL 1990
69
