Originally Posted by jpeter1093
Originally Posted by Bob Pariseau
No. Set the Sub trim to produce the same output level as your other speakers.
The Sub output needs boost to match the other speakers, but when the proper boost is applied the output levels ARE matched.
Now the needed amount of Sub boost is best applied external to the player -- i.e., using the volume knob on the sub itself. If you are running the sub signal through an AVR, the AVR is likely already providing the "standard" boost of +10dB.
So lets say you use Left Front as your reference and with 0dB volume trim in the OPPO it produces 75dB SPL output level. Just set the Sub volume trim to 0dB and adjust the volume knob on the Sub until you also have 75dB SPL. Voila! It doesn't matter whether you are running the signal through the AVR or not -- the goal is to get the levels MATCHED and that's what you've now accomplished.
If you change from all speakers LARGE to some speakers SMALL you will need to redo this level adjustment for the Sub as the amount of boost needed changes in that case.
Thanks, Bob. I'm running the multi-channel analog outputs and am running ALL my speakers as small. In that case, is that where the amount of boost should be 10db? If so, I will do that on the sub's volume control
If any speakers are Small, the Analog Subwoofer RCA jack needs +15dB boost to match the level of the other RCA jacks. If you are running the Analog Sub signal through an AVR, odds are it is already getting +10dB boost added by the AVR -- meaning you only need an additional +5dB boost from the Sub's volume knob. Some AVRs even have adjustable boost levels for different, common configurations (0dB, +5dB, +10db -- the default, and +15dB).
Note that if you play an SACD with DSD-Direct-to-Analog conversion in effect, no audio processing can happen in the player. In particular, Crossover processing can't happen. And thus the player is operating as if all your speakers were set to LARGE. When all speakers are LARGE the Analog Sub output needs +10dB boost, so the Sub volume knob setting you set in your Small speaker configuration would no longer be correct. To avoid having to keep adjusting things, use SACD Output PCM, which lets the player do all its normal audio processing.
Again, keep in mind that when things are set correctly, the output level of the Sub will MATCH the other speakers (when tested with Test Tones or a calibration disc). That is, the end result is that the Sub should sound the same as the main speakers, not 10dB (or whatever) louder.
To test your SACD playback levels, you can use tracks 43-48 of the 5.1 layer of "Stay in Tune With PentaTone", SACD.
TECHIE NOTE: There's an attribute of a good listening room called Room Gain which has the effect of increasing bass levels a couple dB. Movie mixers assume home listening rooms will have about 2-4dB of Room Gain. Thus you may find that you like your bass better if the Sub is set to be, say, 2 to 3 dB hotter than the mains. With a calibrated mic and measuring tools you can find out what's really going on in your room, but most folks don't go that far. The point is, it's OK if you find you like your sub to be set a couple dB hot. Other folks have rooms with significant bass response issues and find they need to turn down the sub (i.e., since they don't know how to address the room issues). It's not uncommon for Subs to show even a 12dB swing across bass frequencies affected by room geometry. If the peaks are in frequencies typically prominent in movie tracks (e.g., 50 Hz for explosions) you might find your Sub sounds too strong even though it measures as being at the right level using a sound meter (which averages a wide range of frequencies). Truly proper bass setup is a complicated topic.