BDP-105 Hardware FAQ
Questions frequently asked at AVSForum about the BDP-105.
The BDP-105 shares the same playback platform as the BDP-103, therefore most questions concerning it that do not revolve around its 'optimized analog audio performance', the 'headphone output' and 'digital coaxial, optical and asynchronous USB inputs' are likely the same as those addressed within the BDP-103 FAQ pages.
What op-amps are you using in the 105? Are they the same amps used in the 95?
For the BDP-105 OPPO is using the same op-amps as the BDP-95: the LME4562.
On the BDP-95 the ESS9018 DAC was stacked 4-DAC channels per stereo Left and Right outputs channel. How are they configured on the BDP-105?
In the BDP-105's stereo board design, the 4 pairs of DACs in the ESS9018 DAC are allocated as: 1 pair for the RCA outputs, 1 pair for the XLR outputs, and 2 pairs stacked for the headphone amplifier.
Does the lack of non-4+4 DAC stacking affect the audio performance?
During the initial design stage, OPPO simply continued the BDP-95 approach by stacking 4 pairs of DAC for each Left and Right channel. However due to the complexity brought in by the newly added headphone amp and USB DAC, OPPO could not achieve an ideal PCB layout. The analog specifications became slightly worse than the BDP-95 in this 4 stacked configuration. OPPO's audio engineers and consultants analyzed the problem and made many experiments to further enhance the quality of the analog output stage of the BDP-105. In the end, they decided that the only way to ensure maximum performance was to separate the current-to-voltage conversion stages for each output path. This change enables us to have a much cleaner PCB layout which minimizes interference and crosstalk. It also eliminates the possibility of the load on one output path affecting the other paths. The drawback is that BDP-105 now loses the benefits of the thermal noise cancellation by stacking 4 DACs. The engineers were able to make up for that by designing an improved power supply, optimizing the filter and drive stages, and beefing up the power and ground paths.
But the numbers (SNR, THD, etc) seem lower than the BDP-95!
OPPO tries to give conservative, nominal specifications in any literature that they produce, even when the player is known to exceed them. OPPO lists the BDP-95's THD+N as -110dB. When OPPO actually tested the player, it was closer to -114dB. The BDP-105's THD+N is also listed as -110dB. In OPPO's testing it was between -115 or -116dB, slightly better than the BDP-95.
Why does the headphone amplifier get two pairs of DACs per channel?
The headphone amplifier gets 2 pairs of DAC because its load is much higher than line-level RCA and XLR outputs.
Are the BDP-105 analog outputs AC or DC coupled?
The BDP-105 analog outputs are AC coupled.
The 95 and 83SE outputs were DC coupled. Why is the BDP-105 AC coupled?
The BDP-95 used DC coupled output, and OPPO found a few rare but annoying compatibility issues with certain amplifiers. Some amplifier may have a DC offset on its input and that has caused issues from popping noises, degraded sound to the audio board becoming damaged. OPPO selected the components carefully so that the AC coupled output can still produce excellent bass response. The capacitors used are high quality ELNA capacitors. Again this increases cost so OPPO did not make this kind of design changes without a good reason. For the unbalanced RCA stereo output, OPPO hired an audio consultant who developed a certain way to bias the components so it actually sounds and measures better than the BDP-95, but requires an AC coupled output.
Overall OPPO believes that the BDP-105 sounds slightly better than the BDP-95 due to the many design changes made in this product. In the end, one has to listen to the player to draw a conclusion. When OPPO first got the ES9018 reference design board a more than two years ago, it measured extremely well but sounded completely "dead". OPPO almost decided against using it and went back to the ES9016 until OPPO actually built our own board to test and found that the ES9018 was indeed better. Audio engineering is a combination of craft and science, and sometimes what is good in theory does not translate to good sound. OPPO's design decisions are based on many years of collective experience from their engineers and consultants, as well as test results from many revisions, and never based on cost reduction.