Originally Posted by csludwig2
Just a side bar: when sending stereo or multi-channel downmixed to stereo via multi-channel L/R analog output or stereo analog output, bass management will have to come from AVR or prepro's DSP. Seems the only means to bass management on the OPPO is from 5.1 SACDs output as PCM, which, of course, treats bass as a channel and permits adjustment of trim/distance on all channels.
That's true of course. If your output is Stereo, there's no way to send out separate, steered bass. You need another wire. So "bass management" in the player wouldn't be useful.
By the way, if you want to play an SACD as Stereo Analog output, you'd be wise to select the Stereo content on that SACD (assuming it is present) instead of do a down-mix on the multi-channel SACD content. The purpose-built Stereo track on the SACD disc will likely give superior results since it has been tweaked by the audio engineer for just that type of listening.
Actually, there *IS* something important to consider here. Ideally when down-mixing multi-channel content to Stereo output you should *DISCARD* any LFE channel content. Why? Because LFE content is, by design, recorded -10dB down. If you want to mix it into the other speaker channels destined for the Stereo output you have to level match -- i.e., lower the other channels -10d, before summing in the LFE (since there is no way to separate out the LFE and provide its required +10dB boost *AFTER* you've done the summation). But you are not done yet. You also have to lower ALL the channels (including LFE) even more for "down-mix attenuation". This provides the headroom so that you can sum all this stuff into just two speakers of output without clipping the output if all the content channels are high volume at the same time.
Now, you can compensate for all this by raising you Main Volume of course. But the problem is, that the substantial attenuation just described lowers the content signals closer to the "noise floor". When you amplify the summed result you are ALSO amplifying the noise floor. Which can make it audible. Simply put, you have discarded dynamic range -- your ability to hear very low volume content cleanly.
In the OPPO, the down-mix provided for the Dedicated Stereo Analog outputs takes care of this automatically. I.e., the down-mix does not include any LFE channel content.
If you are doing the same thing with the multi-channel Analog outputs -- i.e., if you want to wire them to feed just a Stereo output signal -- you can accomplish the same thing by setting LF/RF to LARGE and Subwoofer to ON -- even though the Subwoofer output is not wired! Since LF/RF are LARGE, the full frequency range of the down-mixed normal speaker channels will be included in the Stereo output. But LFE channel content will be dumped to that non-connected Subwoofer output. So the extra attenuation needed to provide headroom for carrying the LFE content is no longer necessary.
TECHNICAL NOTE: This works because audio engineers are not allowed to assume the listener will have a Subwoofer. That means all critical bass must be authored into the regular speaker channels -- which have no lower limit on the frequencies they can carry. The LFE channel, then, is not for ALL bass, but rather reserved for LOUD bass.