Originally Posted by scheong
My BDP-95 is on the latest official firmware (BDP9x-65-0302). HDMI Audio is set to LPCM. SACD Output is set to PCM. I have a 5.1 speaker setup and the BDP-95 is connected to an Anthem AVM50v via HDMI.
Playing tracks 43-48 of the SACD "Stay in Tune with PentaTone" with the 50v volume at -16.5db, I measured the following speaker sound levels with a SPL meter.
LF - 60db, C - 60db, RF - 60db, LS - 61db, RS - 61db, Sub - 68db (fluctuates between 67-69)
Playing the 5.1 LPCM speaker balance tones on the AIX Audio Calibration Disc (Blu-ray) with the 50v volume at -24db, I measured the following speaker sound levels.
LF - 60db, C - 60db, RF - 60db, LS - 61db, RS - 61db, Sub - 63db (fluctuates between 67-69)
I will forward this info to Oppo to see if this is a bug.
Back home now, so I ran some tests tonight on 4 different test discs plus the internal cal tones for ref. All measured with Radio Shack SPL meter C-wtd slow. BDP-93 feeding HDMI bitstreams (except PCM for SACD).
Here is what I notice about the PentaTone disc. It is as they stated:
The level of the subwoofer tone is calibrated so that you should read the same level on a sound pressure meter set to the C weighting scale. (NOTE: The SA-CD standard needs no boost in the LFE channel, in contrast to the 10dB boost required by Dolby Digital.
Which is as Bob commented: >>That is, their SACD LFE test tone is on disc at 0dB compared to the other speaker channels.<<
In my system the LFE gets boosted by 10 dB, so it should read 10 dB higher than the main channels, and indeed it does. Also note that the Explore World and THX Optimizer tones are made with their LFE signals 10 dB lower than the mains so as to shoot for the same SPL overall, and indeed that is how they read. The few dB difference between these two discs is due to use of different spectra in the LFE channel test signals.
The AIX disc is recorded 10 dB louder than the others, and happily, coincidentally, interestingly, the LFE level reads 2-3 dB higher than the mains, just as did the THX signals.
One other thing this confirms is that the Oppo does not do any -10 dB gain shifting of the LFE when playing SACDs. There was some talk of that a while ago.
Conclusion: I see no bug.
I think the reason you do not see the same 10 dB difference between AIX and PentaTone that I do is because our subwoofers have different frequency responses. You did read almost 9 dB increase in the LFE signal on the PentaTone disc, so that's pretty much dead on as expected. The AIX reads high probably because of this wideband issue already discussed. If you have a chance to try a THX disc, that may prove enlightening.
ETA: Added Ratatouille, fixed PentaTone levels.