- Written by John E. Johnson, Jr.
- Published on 15 April 2013
On the Bench
All distortion measurements were within an 80 kHz bandwidth, and I used the XLR balanced outputs of the BDA-2 DAC. All digital test signals were at -5 dB unless otherwise stated.
At 16/44.1, 1 kHz sine wave, and 0 dB, the output was 3.9 volts, which is the maximum voltage the unit can produce. Distortion was 0.002%.
With the same signal at -5 dB, which is a more realistic level, the output was 2.2 volts, and distortion was 0.004%. If you compare these results with the BDA-1, you can see that the BDA-2 has a small, but measurable improvement. (Note however, that the "transport" for the BDA-1 tests was the BDP-1 music server.)
Using 19 kHz and 20 kHz sine waves, at 16/44.1, there were only two small side bands near the fundamentals, and there was no visible B-A peak at 1 kHz.
IM distortion came in at 0.005%, using a 16/44.1 test signal.
The measured frequency response for 16/44.1 was 10 Hz - 19 kHz, ± 0.1 dB, with a 0.8 dB roll-off between 19 kHz and 20 kHz.
The results for 24/96 and 24/192 were the same, so I will illustrate just the 24/192 graphs.
At 1 kHz, THD+N was 0.009%. This is truly excellent!
With 19 kHz and 20 kHz, there were no visible side bands, and there was a visible B-A peak 104 dB below the fundamentals.
IMD at 24/192 was 0.002%.
The measured frequency response at 24/192 was flat to about 25 kHz, followed by a decline of 7 dB out to 90 kHz.
Now, here is a 1 kHz sine wave digital signal played from my computer connected to the BDA-2 through the USB input. The distortion is the same as with the coax input, but notice the improved noise floor, which is significantly lower than with the coax input.
I also measured the jitter reduction of the DAC by inducing a specified amount of jitter in a 10 kHz sine wave and measuring the jitter in the signal from the S/PDIF output jack on the BDA-2. With the signal jittered at 531 picoseconds, the output had a measured jitter of 448 picoseconds, which is a 16% reduction. In other words, the DAC could reduce the jitter with its asynchronous design, by 16%. This is a new measurement for consumer A/V reviews, so we have to wait and see how this compares with other DACs tested down the road.