Originally Posted by Alex Cross
I somehow put my question into the quote. what I am asking is the procedure to calibrate My system when connected via the 7.1 analog outputs from the 103 to a pre/pro
You have to decide whether the pre-pro or the OPPO will do your speaker configuration management. You only want to do that in one place. You disable such stuff in the other place. For example, if the pre-pro is going to do the work, then, in the OPPO, you set all speakers LARGE, equidistant (any distance will do so long as they are all set the same), and with 0dB volume trim. If the OPPO is going to do the work -- which is what I'll assume here -- then you make similar settings in the pre-pro to keep it from also trying to do it.
In the OPPO, set up your desire speaker configuration. In your case, that's a down-mix of 7.1, for example. Also enter your speaker distances -- measured from the front of the grill to your head position at center seating. You also need to decide whether you want the OPPO do to Crossover processing -- steering bass from your normal speakers to the subwoofer. If so, set those speakers to SMALL, otherwise to LARGE. From my post above you'll know that you need to make this choice *BEFORE* you go set your speaker levels. If you've decided to set any speakers SMALL, also select a Crossover frequency. 80Hz is a good, "one size fits all", choice until you have a chance to experiment.
Typically you will do main Volume adjustment for listening using the Volume knob on your pre-pro. In that case, set the Analog output volume of the OPPO to FIXED (= Volume 100). Be sure to set the volume knob of the pre-pro way down until you find out a comfortable setting for it.
OK, now play your calibration track. If you get the AIX disc from OPPO, use the 7.1 LPCM track from the set it offers.
Take your SPL meter and set it to "Slow" response and "C" weighting. If it has a range adjustment, set it to the range for 75dB -- a comfortably loud level that will give you accurate results without being too annoying while you do this.
In the OPPO, set ALL of the speaker Volume trims to 0dB.
Now play the test track and adjust main Volume on the pre-pro until the Left Front speaker measures 75dB SPL. When measuring this, hold the SPL meter so it points straight up towards the ceiling, held at arm's length and positioned at seated ear height at your center seating position. If your seat has a high back or is flush to a wall, move the SPL meter up a few inches or a foot closer to the TV to get it away from such blocking surfaces. You will use this exact same positioning of the SPL meter to measure all the speakers and Sub.
OK so now you have main Volume set so that the Left Front speaker produces 75dB SPL from that calibration track with 0dB speaker volume trim in the OPPO. That's one speaker done.
Now, without changing main volume, measure each of the other speakers in turn. Adjust their speaker volume trim in the OPPO so that they ALSO measure 75dB SPL.
When you get to the Subwoofer, do *NOT* use the speaker volume trim in the OPPO. Leave its Sub trim at 0dB, just like Left Front. Instead adjust the Sub output using the volume knob on the Sub itself. It helps if a friend can turn that while you stay with the meter.
Take another pass around the speakers with the calibration track. They should all measure the same SPL. Voila! That's done.
While you are at it, you can now play the Crossover test track on the AIX disc. That sends a test tone to Left Front that sweeps up and down in frequency from very low bass to mid-range. At the higher frequency end, all of the sound will be coming from Left Front. At the lower frequency end, all of the sound will be coming EITHER from Left Front or from your Sub depending on whether you have a Crossover enabled.
If everything is set up right, that tone should maintain constant volume throughout the frequency range (except for the very lowest bass which is more felt than heard). If you have no Crossover set, this will show you whether your speaker is OK producing that bass on its own. If you have Crossover set, this will show you how smoothly the Crossover transition is working. If the volume goes up and down across the sweep, you could try a different Crossover frequency. In many cases, taming bass output problems is best handled by repositioning speakers/sub. In bass frequencies, even inches matter in terms of how the speaker driver couples bass to the geometry of the room.
Note that if you decide to change from having a Crossover to no Crossover, you will need to revisit your speaker level settings to make sure the Sub output level is correct.