BRYSTON BCD-1
BCD–1 CD PLAYER
THE EVOLUTION CONTINUES
SonIc SuPERiORiTY
ADVANTAGE
The advantage of an all in one box solution for a CD Player
(as opposed to a separate outboard DAC and Drive) is the
elimination of jitter. For optimum performance the Drive
and DAC must use the same MASTER CLOCK. If the
clock signal of the drive is not synchronized with the clock
signal from the DAC then jitter develops.In external DACs
the digital input must be re-clocked in order to reduce the
jitter. Jitter is defined as mistiming of the digital signal.The
timing of all those ones and zeros is of extreme importance.
It isn’t enough to get the bits right; those bits have to be
converted back into music with the same timing reference
as when the music was first digitized. These timing errors
(jitter) are the bane of quality audio. With the Bryston
CD player the master clock and the drive are synchronized
perfectly to eliminate any possibility of jitter affecting the
sound quality of the player.
Over-sampling is when the samples are re-read (2x, 4x, 8x,
etc.) to create a new sampling frequency. The new samples
are then run through an interpolation filter to create a more
analog-like waveform. The output of this process is a very
sensitive analog signal and it is critical that the timing of
this process is very closely controlled by a low jitter clock.
DAC chips also require a very clean digital power supply
if they are to function at their optimum. Noise on the
digital supply may cause added jitter, noise, and distortion.
Incorrect circuit trace routing of the digital power supply
or ground may introduce digital noise into the analog
circuits. This digital power supply is provided from a
separate closely regulated and filtered source. The DAC
also requires a high quality analog power source because the
analog signal is at its lowest magnitude when it enters and
leaves the DAC. As a result, any added noise or distortion
will be greatly amplified by later stages. Again a separate,
heavily regulated and filtered power supply with carefully
routed grounds is provided. Finally, if a digital trace, signal
or power, is routed in a layer above or below an analog trace
it can induce noise via capacitive coupling. Careful trace
routing eliminates these problems and provides the extra
dB’s of noise and distortion reduction which separates good
from outstanding equipment. This attention to detail with
the power supplies is one of the reasons for the superior
sound of the BCD-1 Bryston CD Player.
BRYSTON DAC
The DAC integrated circuit (chip) provides the conversion
of the digital signal to the analog domain.The chip used in
the BCD-1 CD Player is a Crystal CS4398. The CS4398
is a hybrid multi-bit delta-sigma DAC. This is a rather
tongue-twisting description that refers to an advanced
generation chip using a combination of several different
methods to optimize the conversion process. This DAC
uses a process to over-sample the digital input 128 times.
3
PerForMAnce WIthout COMPROMiSE
DISCRETE CLASS-A ANALOG STAGE
Getting the Digital side of the equation correct is only
the start. Once the signal leaves the DAC it is buffered
and increased in strength by operational amplifiers. In
the Bryston BCD-1 CD Player these are constructed
from discrete devices (individual transistors, resistors, and
capacitors) instead of the commonly used integrated circuits.
The use of discrete devices allows the design of a circuit
that exactly matches the needs of the DAC. The use of
integrated circuits always involves compromises since they
are designed as general-purpose devices. Discrete devices
also allow for more powerful outputs from operational
amplifiers since the heat from the output driver transistors
is separated from other devices. In an integrated circuit op
amp this heat can affect the rest of the circuitry since it is
all on one chip.
HAND ASSEMBLED WITH CARE
Bryston hand assembles and individually tests each and
every product we manufacture. We exclusively use only the
finest components in our products, such as 1% metal-film
resistors, polystyrene capacitors, and hand selected and
matched transistors, in order to reduce noise and distortion
to the absolute minimum. Bryston applies techniques and
employs custom materials in our everyday construction
of electronic equipment that are more typically utilized
by military and aerospace industries. Our traditional
adherence to the use of proprietary parts, sophisticated
construction, and refined testing techniques, guarantees
that your Bryston CD Player will perform superbly,without
any problems, for many, many years. It also prevents any
unit-to-unit variance which inevitably is the result of any
mass produced product.
Discrete devices also allow specific matching of important
characteristics such as input and output impedances based
on the specific in-circuit requirements.Discrete operational
amplifiers can also be designed to more closely match their
power source leading to additional reduced distortion and
noise. Discrete devices can be tested very closely to meet
specific tolerances and can be matched against each other
when a desired performance design is critical. Circuits can
be and are designed to require closely matched devices
for optimum performance. Integrated circuits have large
numbers of components on one chip and it is not practical
to do more than high-level sorting of device characteristics.
Bryston does sorting and grading with its DAC chips but
does so to a much finer level with the discrete devices,
which leads to superior sound quality.
PERFORMANCE WITHOUT COMPROMISE
With today’s increased clarity and dynamic range in
recordings you need equipment that not only equals but
surpasses the parameters of the most demanding material
available. The Bryston BCD-1 CD Player is without peer
Bryston Ltd. P.O. Box 2170,
Ontario Canada K9J 7Y4 1-
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