A number of requests for EL DAC benchmarks have popped up lately. Below you’ll find our usual set of tests, conducted in each digital input mode.
- EL DAC v1.01, no DIP switches (filters: SD High, SLOW Low, SSLOW Low)
- JDS Labs 16VAC, 1000mA US transformer
- 3ft USB cable with TDK ZCAT2035-0930 ferrite, connected to a Dell P2715Q USB port*
- Monoprice 6ft TOSLINK cable
- Monoprice 3ft, 75-ohm coaxial cable
- Prism dScope Series III Audio Analyzer
- Windows 10 Pro w/Creators Update*
- Microsoft UAC2 drivers*
* Denotes changes from our 2016 test setup
Our archived EL DAC screenshots from 2016 prototyping contain codenames and irrelevant content; the analyzer test PC has also changed over the past two years. Thus, the entire collection of benchmarks was repeated for this post to give some sense of screenshot consistency. Sampling rates, frequencies, amplitudes, and analyzer configuration data should be discernible for each measurement. Configuration details are essential to anyone who wishes to compare or replicate our measurements, so please feel free to reach out if any information is unclear. As a general reminder, different test setups will produce different results!
Operating System Configuration
Also take note of the operating system setup information found in EL DAC’s Instructions Guide, page 4:
When using USB mode, set sampling rate to the highest integer multiple of your music collection. For example, use 24/176.4kHz for a collection of 44.1k or 88.2k or 176.4kHz files. Use 24/192kHz for a collection of 48k or 96k or 192k audio files. Alternatively, you may use ASIO drivers.
EL DAC automatically selects appropriate clocking rates for Optical and Coaxial S/PDIF modes. S/PDIF input is optimized for 44.1k, 48k, 172.6k, and 192k source sampling rates.
The above suggestions are applicable to all PCM DACs and ensure maximum MCLK rates are provided to the DAC. Deviating from these suggestions will limit MCLK rates, resulting in fewer interpolation samples to the AK4490, and a consequent decrease of 0.35dB frequency response in the highest audible octave. So, follow the instructions guide. More on this another day.
In accordance with these recommendations, the USB Playback device in Windows was set to 24/192kHz for all 48k and 192k tests.
TOSLINK Connectors @ 192k
Before diving into benchmarks, it’s important to note that we have used three different styles of optical jacks in EL DAC since 2016 due to worldwide inventory shortages (no circuitry, ICs, or passives have changed). While all three TOSLINK connectors tested successfully at 192kHz on the audio analyzer, two customers reported unsuccessful optical connections in early 2018, so we promptly exchanged as needed, and eliminated the troublesome optical jacks. OL DAC and EL DAC only ship with the preferred Everlight TOSLINK connector as of March 2018, and benchmarks below were conducted with the Everlight connector.
Frequency Response, 20-20kHz, 192kHZ Sampling Rate
Noise, A Weighted w/8x FFT Buffering
IMD CCIF, 19k+20kHz Tones @ -7dBFS, 192kHz Sampling Rate
IMD SMPTE, 192kHz Sampling Rate
Linearity, 48kHz Sampling Rate
Jitter Components, 12 kHz -1 dBFS Signal, 192 kHz Sampling Rate
Dynamic Range, -60 dBFS Signal, A Weighted, 192kHz Sampling Rate
THD+N Sweep 20-20kHz, -0.15dBFS, Various Sampling Rates (see legend)
The TOSLINK and isolated coaxial inputs rely on the same S/PDIF to I2S controller, thus, performance is similar in most scenarios. Optical and coax modes mode achieve slightly better THD than USB mode. Jitter is more ideal in USB mode, as expected from comparison to an S/PDIF signal. All results exceed our expectations for audible transparency.
As always, discussion is encouraged!
JDS Labs is swamped between several active projects and double digit order growth. Time allowing, we’ll share a measurement perspective of interpolation filters.