SRC•DX Celebrates Its Four Year Anniversary!

The arrival of the Chord Electronics MScaler in 2018 heralded the beginning of a revolution in digital audio. Rob Watts showed the world that better signal reconstruction was possible through extreme application of the theoretical. Improvement in signal accuracy (no matter how small) was audible and a wider 'Sinc' filter (more taps) benefitted transparency and staging. MScaler also cemented the role of Dual-BNC (DBNC or DX) as being Chord's internal interface: two streams of digital coax (SPDIF) using a 'dual data rate' (AES) protocol to support up to 768kHz sample rates. This interface was not proprietary but an extension of a standard professional protocol not implemented in any other manufacturer's product.

It was from this step change in digital audio that a market opportunity opened for OPTO•DX and SRC•DX. OPTO•DX for optical RF isolation of DBNC signals: a fast all-analog waveform follower with optical modulation & de-modulation; and SRC•DX for digital conversion from USB to DBNC. DBNC sounds better than USB because by disabling the USB receiver chip (disconnecting the USB input) means that the DAC has less internal clocking noise and less internally generated RF noise. Further, digital coax is much easier to RF filter than USB. DBNC with Chord DACs is win-win.

In January 2020 (yes, right before the pandemic hit), I made my first SRC•DX sale to a Dave customer who was experimenting with HQPlayer. Since then, sales have spread thanks to user posts on HeadFi and Audiophile Style and the increasing interest in software upsampling. I now provide several supporting products for the SRC•DX & OPTO•DX DBNC signal chain: DC•BLOCK & LP•FILTER, DBNC Adapter for Hugo2/Mojo2, BNC/Coax Assembly, RF•STOP Signal Filter and PGGB•IT!

Regarding OS compatibility:

  • Windows: Any version (including the most recent Windows 11 PRO insider release). SRC•DX is recognized and operates driverless using WASAPI (exclusive mode is recommended). An ASIO driver, if required is provided for download on the SRC•DX product page.
  • macOS: Any version (including the Sonoma update). Tested with MacMini and laptop Macs with USB 2.0 output (direct) or with USB-C output (using the Apple USB-C to USB Adapter).
  • Linux: SRC•DX has sufficient critical mass that users have encouraged device manufacturers to ensure resolution of the known issue of volume attenuation.
    • UBUNTU. All versions. Refer to service note
    • Antipodes/Sonore/Small Green Computer. Refer to service note.
    • SOTM. Fixed in Version 0.5.5. Choose 'Max Volume' button.

Also, here's some useful (anecdotal) information:

  • The 'SRC' in SRC•DX is an abbreviation of 'Source' or (software) 'Sample Rate Converter'
  • The hardware design combined a small FPGA with a ComTrue CT7601 I/O interface chip for USB and SPDIF. This chip is well proven in Asian market audio electronics and the PSAudio Directstream MK2 DAC.
  • SRC•DX is fully compatible as a single digital coax (SBNC) device: for sample rates of 384kHz and lower, the SINGLE BNC LED lights and only Output #1 is active (Output #2 is silent). Otherwise for 705.6/768kHz sample rates, the DUAL BNC lights and both Output #1 & #2 are valid.
  • SRC•DX has had one firmware upgrade in 2021: user downloaded and installed, otherwise the product is current and has remained the same.
  • The pushbutton on the rear switches the HIGH/STD LEVEL to support MScaler/DBNC (HIGH) or SPDIF/SBNC (STD). This has nothing to do with volume: it's a digital voltage level setting to ensure signal compatibility. STD level is preferred.
  • For PCM playback bit-depth, choose up to 24-bits as this is the maximum supported by the SPDIF standard. 
  • For DSD playback, supports DoP up to DSD 128.