Originally Posted by asere
Originally Posted by Torqdog
The same way you have always used it. Play some content, turn the SPL meter on and see what your real time volume levels are.
I know but won't Audyssey set it to 75db to begin with?
Audyssey doesn't set anything to 75db.
What Audyssey does, aside from room correction (to compensate for the effects of your room on the frequency response), is to calibrate for THX Reference levels. The WAY it does this is by playing the calibration sweeps at 75db and then measuring how loud these tones are at the first mic measurement position you use. For example, if your speakers have 89db/w/m sensitivity and are 10' away and in YOUR room, the mic measures an SPL of 74db, the avr then sets that speaker's trim to +1db. If you have 95db/w/m speakers and you're sitting at a different distance, the mic might measure 80db at the MLP, in which case, that speaker's trims would be set at -5db.
Why does it do all this? To set the volume to a known standard (THX Reference). In other words, after the calibration, if you set your avr to Relative volume mode (where the volume readout will usually show -ve numbers that decrease as you turn up the volume), setting the Master Volume to 0db is supposed to replicate the SPL's you would hear in a theater that conforms to THX standards. What does THAT mean? The THX standards state that each satellite speaker (anything that's not a subwoofer) have a maximum SPL at the MLP of 105db, with the LFE channel being able to hit 115db. The theoretical maximum SPL possible if a soundtrack is recorded with maximum volumes in all channels is somewhere around 127db. This is if the digital signal on the soundtrack is recorded at the maximum 0db (with anything softer showing up as -ve numbers).
When you use the Relative volume mode, turning it down to -15db means that the volume heard at the MLP should be 15db softer than THX Reference levels.
The thing is though, that soundtracks could be recorded at any level they choose. A quiet drama with soft conversation will be a lot softer at say, -10db MV than an action movie with lots of gunshots and explosions, which is why folks are suggesting using an SPL meter. Play whatever you want to play and use the SPL meter at your seating position to see how loud the average volume is. If it's too loud, turn it down. If it's lower than the level you're comfortable listening at, then you're good.