Originally Posted by
Bob Pariseau 
Bass management (crossover processing) should only be happening in one place for any given method of listening. The Speaker Configuration settings in the OPPO only apply to the multi-channel Analog outs (and not even then, if you are playing an SACD using DSD-Direct-to-Analog conversion, or are using the Asynchronous USB DAC stereo Input).
So with HDMI Audio output, your crossover processing should be set in your HDMI-capable AVR.
For multi-channel Analog, it is pretty common except in high end models that crossover processing is not available in AVRs. If it *IS* available, that will require the AVR to re-digitize the multi-channel Analog input (since the processing is done digitally) and then re-convert the result back to Analog for output.
For stereo Analog, the AVR likely offers crossover processing, but again this requires re-digitization of the input. If you would prefer to avoid that, then you do the crossover process in the OPPO -- using the multi-channel Analog outputs.
Sophisticated crossover processing which happens as part of Room Correction systems like Audyssey also requires re-digitization.
So, for HDMI Audio the settings in the OPPO don't apply. Make the settings in your AVR.
For multi-channel Analog audio, the way to DISABLE crossover processing in the OPPO (i.e., so you can do it in the AVR instead -- via re-digitization) is to set all speakers to Large in the OPPO. "Large" in this context has nothing to do with the physical size of the speakers. It is just standard language meaning "no crossover processing".
If you want to do the crossover processing for multi-channel Analog in the OPPO, then set speakers to small. You'll need to make sure your AVR is not also doing crossover processing. If your AVR doesn't even offer that, then there's nothing to do. If it does offer it, you'll need to decide how to disable it. Disabling re-digitization -- i.e., some sort of Analog-Direct setting -- would be one way. Another would be to set speakers Large in the AVR -- knowing that the OPPO has already done the crossover job.
Selecting a Crossover frequency is something of a matter of trial and error unless you have a way to measure the actual bass response of your room, and your individual speakers AS POSITIONED in that room. But there are a few Rules of Thumb:
1) Don't set a Crossover too high or you will start shifting male voice dialog into the subwoofer -- not a good thing. Try to keep the Crossover below 100Hz. 80Hz is a better choice.
2) Keep in mind that the Crossover is not a sudden switch between bass in the speaker and bass in the subwoofer. It actually rolls into effect over a range of frequencies -- typically an octave (factor of 2 in frequencies). Throughout that range BOTH the main speaker and the sub will share the job of reproducing the audio. That means that you want to make sure both are ABLE to do that. So if your main speakers are rated down to 30Hz, you don't want to set a 30Hz crossover because the mains will be called on to participate in bass for the octave BELOW the crossover -- 15-30Hz in this example. Instead you should set the Crossover at 60Hz (or higher) so that you know the main speaker can produce quality output for the full octave below the crossover -- 30-60Hz.
3) Even if you have expensive speakers sold as "full frequency range" it is wise to STILL use a subwoofer and crossover processing. That's because even top quality "full range" speakers have trouble producing the lowest bass frequencies AT VOLUME. Unless your main speakers have powered woofers you really should plan on using a decent subwoofer for bass below 30Hz (the bass you more feel than hear).
Before you can test your Crossover you need to make sure your speakers and Sub are matched in volume trim. A calibration disc and a Sound Pressure Level (SPL) meter is the way to do this.
The AIX Audio Calibration, Blu-ray, disc has a Crossover test track which sends a test tone to the Left Front which sweeps up and down through the bass range. At the higher frequency end, all of that should be coming out of LF. At the lowest bass end, all of that should be coming out of the Subwoofer (due to the Crossover). In between, varying amounts come out of BOTH the Sub and LF.
If your speakers and Sub are in proper volume balance, and if your Crossover Frequency is well chosen for the capabilities of your Sub and mains, and if your room has no significant bass response issues, that test should produce constant volume across the frequency range (except at the very lowest frequencies which will be hard to hear). There is another factor that comes in as well and that is the combo of Polarity and Phase settings in the Sub. Both of these are related to keeping the output of the sub in precise alignment with the output of the main speakers through the Crossover range when they are both playing the same bass at the same time. If they are out of Phase then you can get "cancellation" between the Sub and the mains -- which will lead to the perception of anemic bass.
Using a wide frequency range noise tone played into the front speakers (like the hiss between FM radio stations), you can test Phase adjustment in the Sub. Adjust Phase for maximum bass -- i.e., minimum bass cancellation. The effect is subtle (since most of the range of the test tone is not subject to cancellation), so it takes some patience and practice to set this. Phase is a timing effect, so the time alignment of the speakers (speaker distance settings) has to be set correctly first.
--Bob
