12-06-2018, 08:24 AM
Voici quelques explications sur leur DAC (certains points ayant déjà été cités précédemment):
Toslink provides perfect galvanic isolation with zero pF coupling capacitance between source and DAC. This completely eliminates ground loops between source and DAC and related ground loop noise. Ground loop noise usually causes a weak buzzing or humming sound so the background is not ghostly quiet and the ground loop noise will mask low level detail. Ground loop noise can also find its way into the (pre) amps, injecting noise even when the DAC is not playing.
The MOS16 and MOS24 DACs are equipped with a novel type of 4 segment D/A converter with bit power scaling. It basically consists of a combination of two segmented D/A converters. The 8 MSBs are generated by a "high power" D/A converter that offers low output impedance, very fast transient response and very low bit errors. This is a result of the low RDSon resistance in the driver chips and relatively low Ohmic resistors.
The "low power" D/A converter section is used for the remaining 8 or 16 bits. These are based on driver chips with relatively high RDSon and higher Ohmic resistors for high precision and very low bit switching noise. The segmented configuration of both, high and low bit power sections ensures that only those bits are activated that are actually needed for a specific signal level. This greatly reduces jitter sensitivity of the D/A converter and offers superb low level performance without (re)trimming. The noisy bit flip at the zero crossing that occurs with many multi-bit D/A converters is also eliminated by the segmented configuration.
These measures are necessary for highest performance but are not a cure for everything.
There still is the required bandwidth of roughly 12 MHz for audio data to enter from the source. These interfaces cannot differentiate between data and interference that falls within this bandwidth. In short, we cannot prevent some source noise from entering the DAC. It enters together with the S/PDIF signal in the form of ripple voltage and phase modulation.
So some source dependency will always remain. So when we use a cleaner digital audio source, less interference will enter the DAC and sound quality improves. That's why we developed the UPL, it is a very clean digital audio source because it uses low clock frequency (42 MHz typical @ 44.1/16) and low power (approx. 220mW @ 44.1/16) compared to RPI (5 ... 10W, 1GHz), dedicated streamer or PC (50 ... 100W @ 2 ... 4 GHz).
It reads WAV files from the USB memory stick and simply routes the data to the S/PDIF transmitter chip using dedicated hardware circuits on the single, low power CPU. Since no conversion from FLAC or Apple Lossless is needed, noise levels are even much lower as there is no conversion related interference.
The UPL also guarantees bit-perfect playback, always, without any configuration. Are you 100% sure that streaming providers, a RPI or a PC always offer bit-perfect playback?
Playback is not bit-perfect when using software volume control, software mixing, software equalising or software upsampling. 44.1/16 albums are end products that include extra information (more than 16 bit) in the form of a carefully calculated dither pattern. This dither pattern and the extra resolution it provides is instantly destroyed when we perform further digital manipulations on this end product. That's why it is so important to maintain bit-perfect playback.
Similar, there is low and high quality software for manipulations in the digital domain. On a consumer product with cheap or free digital manipulation software the quality will not be that great.
Toslink provides perfect galvanic isolation with zero pF coupling capacitance between source and DAC. This completely eliminates ground loops between source and DAC and related ground loop noise. Ground loop noise usually causes a weak buzzing or humming sound so the background is not ghostly quiet and the ground loop noise will mask low level detail. Ground loop noise can also find its way into the (pre) amps, injecting noise even when the DAC is not playing.
The MOS16 and MOS24 DACs are equipped with a novel type of 4 segment D/A converter with bit power scaling. It basically consists of a combination of two segmented D/A converters. The 8 MSBs are generated by a "high power" D/A converter that offers low output impedance, very fast transient response and very low bit errors. This is a result of the low RDSon resistance in the driver chips and relatively low Ohmic resistors.
The "low power" D/A converter section is used for the remaining 8 or 16 bits. These are based on driver chips with relatively high RDSon and higher Ohmic resistors for high precision and very low bit switching noise. The segmented configuration of both, high and low bit power sections ensures that only those bits are activated that are actually needed for a specific signal level. This greatly reduces jitter sensitivity of the D/A converter and offers superb low level performance without (re)trimming. The noisy bit flip at the zero crossing that occurs with many multi-bit D/A converters is also eliminated by the segmented configuration.
These measures are necessary for highest performance but are not a cure for everything.
There still is the required bandwidth of roughly 12 MHz for audio data to enter from the source. These interfaces cannot differentiate between data and interference that falls within this bandwidth. In short, we cannot prevent some source noise from entering the DAC. It enters together with the S/PDIF signal in the form of ripple voltage and phase modulation.
So some source dependency will always remain. So when we use a cleaner digital audio source, less interference will enter the DAC and sound quality improves. That's why we developed the UPL, it is a very clean digital audio source because it uses low clock frequency (42 MHz typical @ 44.1/16) and low power (approx. 220mW @ 44.1/16) compared to RPI (5 ... 10W, 1GHz), dedicated streamer or PC (50 ... 100W @ 2 ... 4 GHz).
It reads WAV files from the USB memory stick and simply routes the data to the S/PDIF transmitter chip using dedicated hardware circuits on the single, low power CPU. Since no conversion from FLAC or Apple Lossless is needed, noise levels are even much lower as there is no conversion related interference.
The UPL also guarantees bit-perfect playback, always, without any configuration. Are you 100% sure that streaming providers, a RPI or a PC always offer bit-perfect playback?
Playback is not bit-perfect when using software volume control, software mixing, software equalising or software upsampling. 44.1/16 albums are end products that include extra information (more than 16 bit) in the form of a carefully calculated dither pattern. This dither pattern and the extra resolution it provides is instantly destroyed when we perform further digital manipulations on this end product. That's why it is so important to maintain bit-perfect playback.
Similar, there is low and high quality software for manipulations in the digital domain. On a consumer product with cheap or free digital manipulation software the quality will not be that great.