Micromega CD 30 MM CD30SILVER Manual Do Utilizador
Códigos do produto
MM CD30SILVER
are essential factors in determining reproduction quality. We decided on a specific component whose
jitter is lower than 1ps on a range of 1 kHz for any frequency lower than 52 MHz. The frequency
chosen for this clock is 16.9344 MHz which is 128 times the final sampling frequency of 132.3 kHz. In
addition, the SRC makes it possible to take upmost advantage of the benefits provided by current
digital-analog converters. It should be remembered that the original resolution of CD is 16 bits. Under
no circumstances can this native resolution be increased, but on the other hand SRC’s represent an
ideal interface between the audio data formatting circuit and the digital-analog converter. The
formatting circuit exports its data at 44.1 kHz for words of 16 bits in length. All modern digital-analog
converters accept input words of 24 bits and this is particularly true since the arrival of DVD. If CD
resolution remains at 16bits, the SRC will transform its word length into 24bits and internal
oversampling of the SRC will make it possible to benefit as much as possible from the digital-analog
converter’s capabilities.
jitter is lower than 1ps on a range of 1 kHz for any frequency lower than 52 MHz. The frequency
chosen for this clock is 16.9344 MHz which is 128 times the final sampling frequency of 132.3 kHz. In
addition, the SRC makes it possible to take upmost advantage of the benefits provided by current
digital-analog converters. It should be remembered that the original resolution of CD is 16 bits. Under
no circumstances can this native resolution be increased, but on the other hand SRC’s represent an
ideal interface between the audio data formatting circuit and the digital-analog converter. The
formatting circuit exports its data at 44.1 kHz for words of 16 bits in length. All modern digital-analog
converters accept input words of 24 bits and this is particularly true since the arrival of DVD. If CD
resolution remains at 16bits, the SRC will transform its word length into 24bits and internal
oversampling of the SRC will make it possible to benefit as much as possible from the digital-analog
converter’s capabilities.
Digital to analog conversion: AD1853
CD30 calls upon one of the best dedicated digital-analog converters currently available. We chose the
Analog Devices AD1853 because of its unbeatable value for money. This converter with its dynamics
of 110dB, its signal to noise ratio of 112dB and its THD + Noise figure of < -100dB is the ideal
converter for treating signals from the SAA7824 as accurately as possible. The power supply with
constant current source and shunt regulators ensures total immunity from external disturbances. The
local decoupling ensured by very low inductance, very low series resistance capacitors, guarantees
better signal integrity for the analog stages. The signals generated by the SAA7824 enter the AD1853
at 44.1 kHz. They are converted internally and oversampled 8 times in a digital filter whose out of band
rejection is higher than 115 dB, pushing very far back from the audio band the first images of the
digital filters. That makes it possible to have analog filters of a relatively low order while minimizing the
energy transmitted out of the band. The design of the printed circuit is critically important and the
MICROMEGA team put all its know-how into this part, which represented a challenge in more ways
than one. The circuit, which was designed using the most modern software, is optimized to take into
account the extraordinary possibilities of the selected components. Any design error can be costly,
both in terms of measurements and listening quality. The AD1853’s current outputs in differential
mode enable it to preserve the intrinsic dynamics of the signal and to reject in common mode any
disturbance which could have affected the signal. Despite all the precautions taken in terms of the
layout, it may be that at certain times some external phenomena affect the signal. In this particular
case, the differential mode proves to be extremely effective. Indeed, the principle of differential mode
consists of conveying a signal in two separate branches, one of which is in opposite phase to the
other. If a disturbance affects the signal it will simultaneously affect the phase of the two branches.
When the differentiator comes into play between the two signals, this disturbance will be totally
cancelled. It is what we call in technical jargon the common mode. Therefore, we can affirm that a
differential signal saves 6 dB of dynamics and totally rejects any signal in common mode, taking into
account the differentiator’s common mode rejection factor. A subject often discussed is that of
symmetrical connections. These were invented in the past in the professional field to transmit low level
signals such as microphone signals, to eliminate ambient disturbances and in particular, hum due to
mains cable radiation at 50 Hz.
Analog Devices AD1853 because of its unbeatable value for money. This converter with its dynamics
of 110dB, its signal to noise ratio of 112dB and its THD + Noise figure of < -100dB is the ideal
converter for treating signals from the SAA7824 as accurately as possible. The power supply with
constant current source and shunt regulators ensures total immunity from external disturbances. The
local decoupling ensured by very low inductance, very low series resistance capacitors, guarantees
better signal integrity for the analog stages. The signals generated by the SAA7824 enter the AD1853
at 44.1 kHz. They are converted internally and oversampled 8 times in a digital filter whose out of band
rejection is higher than 115 dB, pushing very far back from the audio band the first images of the
digital filters. That makes it possible to have analog filters of a relatively low order while minimizing the
energy transmitted out of the band. The design of the printed circuit is critically important and the
MICROMEGA team put all its know-how into this part, which represented a challenge in more ways
than one. The circuit, which was designed using the most modern software, is optimized to take into
account the extraordinary possibilities of the selected components. Any design error can be costly,
both in terms of measurements and listening quality. The AD1853’s current outputs in differential
mode enable it to preserve the intrinsic dynamics of the signal and to reject in common mode any
disturbance which could have affected the signal. Despite all the precautions taken in terms of the
layout, it may be that at certain times some external phenomena affect the signal. In this particular
case, the differential mode proves to be extremely effective. Indeed, the principle of differential mode
consists of conveying a signal in two separate branches, one of which is in opposite phase to the
other. If a disturbance affects the signal it will simultaneously affect the phase of the two branches.
When the differentiator comes into play between the two signals, this disturbance will be totally
cancelled. It is what we call in technical jargon the common mode. Therefore, we can affirm that a
differential signal saves 6 dB of dynamics and totally rejects any signal in common mode, taking into
account the differentiator’s common mode rejection factor. A subject often discussed is that of
symmetrical connections. These were invented in the past in the professional field to transmit low level
signals such as microphone signals, to eliminate ambient disturbances and in particular, hum due to
mains cable radiation at 50 Hz.
The analog stages
Bearing in mind what has been previously discussed, the differentiating stages had to be as equally
efficient as the other component’s performances. The choice was difficult because, as specialists
know well, measurements and listening do not always go hand in hand; there is always an empirical
part which remains and experience in the audio field is thus essential. Although SMD components are
often rejected by the most extreme purists, once again experience proved that it is not as simple as
that. You have to be wary of taking shortcuts as they often turn out to be very limiting. Each
technology has its advantages and disadvantages, but it is clear that when working with signals of very
efficient as the other component’s performances. The choice was difficult because, as specialists
know well, measurements and listening do not always go hand in hand; there is always an empirical
part which remains and experience in the audio field is thus essential. Although SMD components are
often rejected by the most extreme purists, once again experience proved that it is not as simple as
that. You have to be wary of taking shortcuts as they often turn out to be very limiting. Each
technology has its advantages and disadvantages, but it is clear that when working with signals of very