- Written by John E. Johnson, Jr.
- Published on 27 June 2011
On the Bench
Keep in mind that the bench test results for the BDP-1 reflect the fact that the BDA-1 DAC was in the signal path. Distortion measurements were made within an 80 kHz bandwidth. The BDP-1 was connected to the BDA-1 using an XLR balanced cable, and the analog XLR balanced outputs were used to collect the bench test data. The volume control on the BDA-1 was set to maximum. The test files were loaded onto a USB thumb drive which was plugged into a port on the front panel.
Using a 1 kHz sine wave, recorded at 0 dB, THD+N was 0.003%. Note that 0 dB is the highest level a signal can be recorded digitally.
The same test, measured with my usual recorded signal level of - 5 dB, made no significant difference in the distortion. I have used test signals recorded at - 5 dB for my previous reviews, because this is more in line with what a consumer might encounter with a recording.
With a combined signal of 19 kHz and 20 kHz sine waves, there was no measureable B-A peak at 1 kHz. Only a few, very small peaks are adjacent to the fundamental peaks, which is excellent.
IMD was a miniscule 0.006%. Translating a number like this to the sound one would experience, there would be much greater audible detail than if there were significantly higher IMD, which would produce numerous significant intermodulation peaks that obscure the detail.
The measured frequency response at 16/44.1 sampling was 20 Hz - 20 kHz, - 0.1 dB, right on spec for the DAC.
The jitter spectrum below indicates an average of about 5-8 pico-seconds, with a rise at the low end of the spectrum to about 20 pico-seconds, again, right on the specification. In this test, I connected the digital test signal output from the BDP-1 to my Audio Precision test instrument. The BDA-1 DAC was not part of the signal chain for this test.
I ran tests at 24/96 and 24/192. The results were identical, so I will present only the 24/96 graphs.
At 1 kHz, distortion was 0.003%, very close to what it was at 16/44.1.
The B-A peak at 1 kHz is just barely visible in this test using 19 kHz and 20 kHz sine waves. The noise floor is a bit lower than with the 16/44.1 test, so that is why it is now visible.
IMD was a bit lower with 24/96 sampling than with 16/44.1. However, I consider this difference insignificant.
The measured frequency response was 20 Hz - 20 kHz, - 0.1 dB for both 24/96 and 24/192. Also, for both sampling rates, the response was down 1 dB at 40 kHz.