bel canto Asynchronous USB and Ultra-Low Phase-Noise Clocks Explained

Transcription

1 Asynchronous USB and Ultra-Low Phase-Noise Clocks Explained Bel Canto introduces the REFLink, ulink and mlink Asynchronous USB 2.0 Audio Interface Converters for the very highest in quality audio playback from USB sources. Asynchronous USB and Phase-Noise It s All About the Clocks Asynchronous USB actually decouples the critical audio clock from the computer stream. So Bel Canto s new Asynchronous USB Link Converters output noise and jitter performance is determined by the quality of master clocks used in the REFLink, ulink and mlink. Since the master clocks in Bel Canto Asynchronous Converters are now free-running and isolated from the incoming data stream we achieve big benefits from the new Low and Ultra-Low Phase-Noise Clocks. Ultra-Low Phase-Noise Clocks Figure 1a No Phase-Noise Figure 1b Double-Sideband Phase-Noise Figure 1a represents a theoretically perfect single tone clock with no additional phase noise. Actual crystal oscillators have phase noise more like that shown in Figure. 1b. Note the amplitude rising as the signal approaches the 10Mhz clock frequency The phase-noise is expressed as jitter or variations in the clock edge that s converted to noise in the output of an audio DAC. Lowering these sidebands lowers the noise and jitter resulting in cleaner output. 1 Engineered to Engage bel canto

2 Low Phase-Noise mlink Oscillators bel canto Carefully chosen Low Phase-Noise Oscillators used in the mlink USB Converter already feature noise levels 10-to-100 times lower than typical oscillators. The phase-noise for the mlink oscillators is shown in figure 2 below. Figure 2 Demonstrates the Single-Sideband Phase-Noise of the Low Phase-Noise Oscillators used in the mlink. Note that integrated phase-noise from 100Hz-to-1MHz results in jitter levels of only 222 femtoseconds or 0.222pS (picoseconds). 2 Engineered to Engage bel canto

3 The Ultra-Low Phase-Noise ulink and REFLink Oscillators The performance of the Ultra-Low Phase-Noise Oscillators used in our new ulink and REFLink USB Converters are shown in Figure 3 below. Figure 3 shows the Single-Sideband Phase-Noise of our Ultra-Low Phase-Noise Oscillator. Note the extremely low -170dBc noise floor that s critical for the clock s best sound quality. Integrated phase noise from 100Hz-to-1MHz is only 50fS (femtoseconds) or 0.05pS (picoseconds) and that s 100-to-1000 times lower than typical audio clocks! The Ultra-Low Phase-Noise Clock performance makes the Bel Canto ulink and REFLink essentially noise-free sources that take the digital out of digital sound! The sonic impact of lowering noise to this degree is stunning, delivering a highly organic analoglike sound. You ll enjoy much improved soundstaging and spatial positioning, micro- and macrodynamics and a sense of openness. You ll immediately hear longer acoustic decay times and a resultant sense of air plus better, tighter, more controlled bass. 3 Engineered to Engage bel canto

4 REFLink, Lower Noise and Better Isolation The Bel Canto REFLink features a High Speed USB input and a choice of digital audio outputs including coaxial SPDIF on a BNC connector, balanced AES on an XLR connector, and the astonishingly fine-sounding ST Fiber featuring Bel Canto LightLink circuitry. Sampling rates up to 192kHz and word lengths up to 24-bits are supported. Great care has been taken in the design of the REFLink to optimize the asynchronous interface between the internal 500MHz DSP core and the dual ultra-low phase noise oscillators to insure the lowest possible jitter on all three of the digital audio outputs. Multiple stages of low noise, isolated power supplies drive individual sections of the circuit, while the output master clocks and line drivers are powered by a separate low-noise power supply. There are two stages of galvanic isolation between the USB input and output and clock stages. No power is drawn from the USB input reducing possible corruption and performance sensitivity from the USB cable and internal power on the computer source. The USB input and processor core are on a daughter card plugging into the main board with its Ultra-Low Phase-Noise Oscillators, output drivers, primary power supply and filters to insure optimum isolation between the USB input and its ultra-clean digital audio outputs. Many factors contribute to the superb audio performance of the REFLink including the low-noise electrical environment, isolation from mains-borne noise, the sophisticated 500MHz DSP core and software, the ultra-low phase-noise oscillators plus the high-current high-speed CMOS drivers and retiming devices. Finally Bel Canto s LightLink technology High Speed ST Fiber output provides the absolute best performance with our DAC3.5VB. The Bel Canto USB Link Converters are designed to work with both Apple Macintosh and Windows PC computers. MAC Systems The native USB 2.0 audio drivers work with OSX 10.6 or later. Your new mlink, ulink or REFLink converter appears as Bel Canto ulinkusb2.0 in the Sound application and should be selected as your default playback device. itunes can manage your music library but you ll get much better performance using additional software that links with itunes. Bel Canto recommends Pure Music, Amarra or Audirvana Plus in Memory Playback mode. These software packages use the itunes interface and guarantee bit-perfect playback using proprietary engines for best sound. 4 Engineered to Engage bel canto

5 PC Systems You must install custom PC drivers for use with Windows XP or Windows 7 available at Once installation is complete you then select Bel Canto ulinkusb2.0 in the Sound application. JRiver Media Center works very well in the PC environment and it also ensures the best audio quality with bit-perfect playback and proprietary playback engine. Be sure to use WASAPI Event Style for the Audio Output (Options/Audio/Audio Output/Output Mode) and make sure No Change is selected for all sample rates, what comes in goes out up to 192Ks/s. (Options/Audio/Settings/DSP & Output Format) Once you ve set up your PC or MAC computer you can connect to your DAC of choice, no doubt a Bel Canto! mlink ulink REFLink Proprietary 500MHz DSP Bel Canto Asynchronous USB Core Dual Ultra-Low Phase-Noise Clocks Dual Low Phase-Noise Clocks Dedicated Low-Noise Power Supplies USB Buss Power, LC Filters and Local Power Regulation Multi-Stage Galvanic Isolation Single-Stage Galvanic Isolation Native Drivers with Mac OSX 10.6 or Later Custom driver for Windows 7 or XP Input High Speed USB Type-B Receptacle Output Coaxial SPDIF on BNC Output LightLink ST on ST Fiber Output Balanced AES/EBU on XLR BNC/RCA Adapter Included Supported sampling Rates: 44.1, 48, 88.2, 96, 176.4and 192kHz Supported Word Lengths: Up to 24-bits Full e.one Chassis and Front Panel Sample Rate Display Sample Rate LEDs Indicate 44.1, 48, 88.2, 96, and 192kHz On/Off Power Switch Power Requirement 120VAC/60Hz or 240VAC/50Hz Set Internally Dimensions 8.5 W x 12.5 D x 3.5-inches H (216 x 318 x 88mm) Weight 14lbs. (6.5 kg) Dimensions 4 W x 4.75 D x 1.2-inch H (103 x 120 x 30mm) Weight 1lb. (0.45kg) USB Cable No No No 5 Engineered to Engage bel canto