Singxer C1 (FEMTO AS318B ACCUSILICON)- USB Digital Interface Board – XU208 chip




Singxer C1 – FEMTO AS318B


Each output interface supports sample rates:

176.4kHz, 192KHz, 352.8KHz, 384kHz
[Wherein I2S out support full sample rate, S/PDIF supports up to 192KHz]
DSD: 2.8 MHz (DSD64) – DoP,native
5.6 MHz (DSD128) – DoP,native
11.2 MHz (DSD256) – DOP,native
[Wherein all DSD format support I2S out, S/PDIF and AES/EBU support DSD64 DOP mode]
32 bit over I2S output
24 bit over S/PDIF
System Compatibility:
1, Windows 7, Windows 8, Windows 10; 32/64 bit, you need to install special drivers
2, Native MacOS 10.6 and later, using the system comes with drivers
3, Native Linux with UAC2 compliant kernel, using the system comes with the driver (in Ubuntu and Daphile systems tested above, based on INTEL X86 platform)
4, Android OS 4.2 and above, the device needs to support OTG function, in general, Android 5.0 system is supported by default, with recommendation 5.0 below special player.






If it doesn’t show in stock, It would be backordered with a 1-2week delay typically.

Otherwise, if it shows in stock, then we have it in our hands and ready to ship!


Out of stock


C1 comes in two versions  – NDK/EPSON and FEMTO/AS318B

This is for the FEMTO VERSION (pins on end of board are not soldered as they can be mounted on either side of the board depending on application)

We are the Singxer USA distributor! Shipped from USA!

 C-1 digital interface module xCORE-200 interface U8 XMOS new upgraded version of the second generation XMOS chip developed high-XU208 USB interface also supports firmware upgrade interface. Schematics and firmware (including XMOS and CPLD) are our own development, not the public version.

  We are the world’s first manufacturer to successfully develop with the XMOSXU208 chip.

        C-1 uses a customized version of femtosecond TCXO, its long-term accuracy of the clock is 1PPM. ACCUSILICON AS318B. 

   Femtosecond refers to short-term stability of the crystal, usually with phase noise or jitter values.Usually crystal jitter parameters are expressed using ps, but when the jitter value lower than 1PS when expressed on the use of femtosecond (fs). Only a few specially optimized to achieve crystal femtosecond jitter performance

     1PPM is refers to long-term stability of the crystal, is used to measure the long-term frequency error of the clock, usually represented by PPM, 1PPM is a millionth.

      These are two different concepts. For digital audio, first pursuit of jitter performance, followed by the long-term stability. The C-1 using the crystal, both jitter performance and long-term stability, have reached a new level. 

   C-1 is positioned in our product line as a high-end performance and mainly adopted with these two Technologies:
 1, source-synchronous technology and CPLD shaping technology;

2, the independent development of the system clock, using customized high-performance crystal , ultra-low phase noise, low jitter.

XU208 second generation XMOS chip memory than U8 double computing speed of terror 1000MIPS, U8 of 500MIPS than doubled.

Singxer C1


Product Description:
C-1 digital interface of our team to develop a high-performance USB digital audio interface, using the XMOS latest xCORE-200 series chips. C-1 is the use of ultra-low jitter clock system’s digital interface. C-1 digital input interface using a standard USB2.0 interface, while F-1 has a wealth of output interfaces, including I2S interface.
1, C-1 is a use of the latest XMOS xCORE-200 series of high-end USB digital interface products. New generation XMOS chip, using more advanced process technology, performance than the older chip U8 doubled, reaching 1000MIPS processing capabilities.

2, it is known, the weight of the core is digital audio algorithms. Our team in the field of digital audio work for many years, and the strong support of XMOS FAE team, we conducted a number of technical improvements and optimization algorithms on the basis of the original firmware.

Singxer C1


Screw position, I2S pin position is fully compatible with Italy Amanero module; the entire board with three crystal design, which is a customized version of the audio oscillator femtosecond oscillator, SMD small size package.

diagram C1 singxer

Each interface electrical standards:

1, USB input socket is a standard USB-B type female, USB power supply range 4.5V-5.1V;

2, RCA connector outputs standard S / PDIF signal level is 550mV (standard connection load), the output impedance of 75 ohms;

Design details:
1, carry out electricity as the mother of the acoustic design concept, pay attention to the power supply circuit design, high-performance, low noise and fast response LDO as the main power source. The entire board using a 2-way power supply independent LDO, wherein the clock section even using ADI’s ultra low noise LDO, in order to ensure the ultimate output performance laid a solid foundation.

2, PCB board with 4-layer circuit board design, ensure that you have full power and ground plane layer, using the method of high-speed digital design, signal integrity and power integrity of the entire board. The clock signal for special treatment, using package design and precise impedance control, thereby ensuring the signal quality and increase the clock anti-jamming capability. Input and output signals follow a standard design, especially high-speed USB signals using a 90 ohm differential impedance control.

Singxer C1

Here are two ultra-low jitter measured phase noise crystal dedicated audio, you can see and CCHD series CRYSTEK performance is just as good in a wide frequency range has been femtosecond jitter performance levels:

phase noise c1


RMS Jitter C1

I2S signal output socket Description:
1, MUTE is high mute; the DSD data stream DSD_ON high level;
2. All electrical average LVCMOS, voltage of 3.3V;
3,3.3+ output power, low output current 50mA;
4, MCLK clock output 22.5792Mhz or 24.576Mhz;

5, FS0, FS1, FS2 sampling rate indicator level, FS3 not;

C1 Freq select C1 Header



Note from Kitsune: Singxer C1 -There are two versions of the C1, basically one is a femto version and one is pretty close to femto. 😀 The NDK/EPSON version is almost femto level. The performance is nearly identical, yet the other version which has the Accusilicon AS318B clocks are slightly better.  We find them to be both excellent choices and these are considered one step below the F1 model that Singxer Offers as their flagship USB module.

order of performance/features

F1>C1 (femto)>C1(NDK)>X1>Q1


The Accusilicon AS318B version (download data sheet here)


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