Digital audio signal
sources have become more and more popular in the high end Hi-Fi
market. The CD player, which appeared in the early eighties, has
been followed by the DAT recorder, satellite radio, and recently
by Mp3 players, the MiniDisc and DAB radio.
Digital audio has great advantages, but it
does leave one particular sensitive spot: The conversion of the
digital data to an equivalent analog signal must be done with
ultimate precision, if the sound quality contained in the digital
material is to be achieved.
The design of the Minuet
Fundamental to the Minuet is a
sound mechanical construction: The circuitry is divided into
modules, each module screened by a heavy aluminum frame. Thus the
digital parts, known to be a potential source of noise, are kept
completely separated from the analog parts. These in turn are
divided into modules for each channel, Left and Right.
The modularity allows for easy future upgrading.
To further eliminate digital noise, the
complex IC's in the digital module and the sensitive converter IC's
in the analog modules, have all been wrapped in thick silver foil.
The Minuet comes in a single ended as well as in a truly balanced version.
Power Supply
The supply of power within the Minuet
is done without compromise: Analog and digital supply are kept
completely separate, right down to the mains line, which is
filtered.
There are two levels of voltage regulation,
with a total of 25 regulators (41 in the balanced version).
Bypass capacitors are high quality polypropylene throughout the
analog supply.
The Signal Path
The digital circuit uses an eight-times
oversampling filter, which interpolates the 16-bit audio data
with 20-bit precision.
The analog circuit is based on the new Burr-Brown
PCM1702P converter IC, in the especially selected "K"
version. This converter has 20-bit resolution, and is based on
the technically superior Advanced Sign Magnitude architecture.
The analog signal path is DC coupled and it
is kept as simple as possible using the best discrete components
like high voltage polypropylene capacitors and special non-magnetic
resistors. To ensure the necessary protection of amplifiers and
speakers and to prevent the converter from influencing the
working conditions of amplifiers and speakers a low pass filter
is built around two Analog Devices AD845KN operational amplifiers.
The low pass filter is of the soft "Bessel"
variety, which has a constant time delay up to and beyond 100 kHz.
In combination with the digital oversampling filter this means
that the phase response is virtually the same. as it would have
been without filter.
The standard single-ended Minuet has
one converter IC per channel. In the balanced version, the phase-splitting
is done digitally, and there are two identical analog circuits
for the positive and negative phase. Thus, the balanced Minuet
uses four converter IC's totally.
Connectors
The Minuet has a one-of-four
input selector. The inputs are equivalent, and can be connected
to any digital source: CD, DAT, DCC, MiniDisc, Mp3 players or digital radio.
The converter switches automatically to the appropriate sampling
rate. The chosen input input is copied to the digital output for
recording purposes.
The standard Minuet uses high
quality non-magnetic gold-plated BNC connectors for the digital
signals, but other options are available: AT&T ST-type
optical connectors offers the best possible optical link, while
TOSLINK optical connectors, and RCA electrical connectors are
compatible with a wide range of products, eliminating the use of
special cables.
The use of BNC connectors however
are recommended as to RCA connectors for the digital inputs.
The analog outputs are high quality RCA
sockets from WBT for the single-ended version. The balanced
version uses professional XLR sockets from Neutrik.
A phase inverter, working in the digital
domain, is present as well. This is for adjusting the absolute
phase. Whether this should be done depends on the recording.
Finish
Housed in an elegant slim-line case, with a black front, and round gold-plated buttons with red LED indicators, the Minuet goes very well with the Moerch tonearms, as well as most third party equipment. On special order, a luxurious all-gold front or chrome front is available.
