Originally Posted by indebtbassfreak
Mike, i just read the section of "increasing volume with two sub woofers". I havent finished my first cup of coffee yet so bare with me. Since i always thought adding 5db trim per sub out (would) equal 10 total DB's of boost, i find this section very interesting.
Am i understanding correctly that if your avr has two sub outs, one to each identical sub,,,, and although audyssey is trying to set (all) channels to say 75db's, it is actually combining both sub channels to equal 75db's (total) despite having audyssey running sweeps separately? Thats what i'm understanding (if i'm awake enough). If thats the case, then i completely get the math with regards to adding trim via LFE channel equaling 5db total, not 10.
(If) so far i'm correct in my understanding, how then would it play out if the boost was added through individual sub gain, not avr trim? If i added 5DB's of gain per sub what would that equate to, 5DB total, or 10?
Some of this stuff makes my head spin sometimes, regardless of coffee. Seriously! Audyssey and all other forms of automated calibration with which I am familiar, sum the SPL from multiple subwoofers. So, we use the first test tone for level-matching, and for setting the AVR trim levels on multiple subs individually. And, the two, or four, or eight subwoofers in our systems are calibrated to produce a combined volume of 75db, as measured at the MLP in microphone position 1.
After the calibration, if we raise the volume symmetrically, using either the gain controls on the subs, or the trim controls in our AVR's, the net increase will still be the summed number of the two subs. So, +5 in gain from two subs (or from ten subs) will still equal +5db. The same thing will be true for trim increases.
Asymmetrical increases are a little different, but still follow the same summed rule, as explained in this section of the Guide:
We still have the full benefit of our extra headroom from dual subs available to us, but we have to utilize that additional headroom in the way I described above. If we want +10db, for instance, we have to increase each subwoofer by that amount using either sub gain, or AVR trim, or a combination of the two.