Quote:
Originally Posted by
MikeyD360 
On the subject of hot v reference, I don't know as dont have an SPL meter to see what's going on - but Audessy has set most of my channels to -9 to -10.5 when I look at channel level settings. I leave the sub where Audessy sets it, apart from 2ch music, where I bump it up to -5.
If Audessy is going to make across the board level reductions, why not instead make smaller reductions to fewer channels?
I.e instead of LCR, SR SL, SBR SBL SW all being -9, -9.5. -10 etc, why not just -1.5 or -2 as this seems to be the differential between the channels. Soz if this is a dumb or off-topic question.
There are 2 things at work here, Reference Level Calibration and the sensitivity, (efficiency) of of your speakers. Let's start with sensitivity.
Sensitivity is measured in an anechoic chamber by sending the speaker a 1 watt signal and measuring the SPL output 1 meter away from the speaker. Some speakers can take 1 watt of input and produce 95 or more dB of output. Others may take that same 1 watt and only produce 85 dB. That 10 dB difference is perceived to be twice as loud, but it requires more than 8X as much power to drive an 85 dB sensitivity speaker as it does to drive a 95 dB sensitivity speaker.
Calibration of the speakers/subwoofer(s) system is intended to ensure that all the speakers produce the same level at the listening position when they are sent the same input signal. You don't want the L/R speakers outputting higher than the CC and surrounds, or you won't hear the CC and surrounds in proper balance. You want them all at the same level so the sounds will be heard as the mixer intended you to hear them.
Audyssey's Reference Level Calibration is intended to set the levels such that, when the speaker is sent a "Full Scale" signal, the speaker puts out 105 dB with the Master Volume Control at "0". This is the reference standard calibration for a digital recording. However, if you used a 105 dB test signal for calibration, it would be extremely loud, you would need ear plugs to perform it. Some speakers can't even handle this loud of a signal. Therefore, they instead use a signal meant to be set at 75 dB. This is refereed to as a -30 dBFS signal, or 30 dB below Full Scale, (105 - 30 = 75). The speaker trims are then set so the SPL measured at the listening position is 75 dB.
To tie this all together... if you have high sensitivity speakers, in order to get the SPL to measure 75 dB at the LP, the trim needs to be turned down to a negative number. The higher the sensitivity of the speakers, the lower the trim setting. The lower the sensitivity of the speakers, the higher the trim setting. So, when Audyssey sets your speakers to -9 or -10, that just means you have fairly high sensitivity speakers.
You can change the trim settings if you like, as long as you change them all
by the same amount to keep them all calibrated relative to each other. The only thing it will change is the setting of Reference Level on the Master Volume Control. If you don't care where the MVC needs to be set to output RL, then feel free to change them. However, just realize that there is no difference between the speakers trims set at -10 with the MVC set at 0, and the speaker trim set at 0 and the MVC set at -10. They'll both result in the same output. IOW, there is no benefit to changing them; it only changes the position of RL on the MVC.
In terms of the subwoofer trim, that is additionally affected by the level setting on the subwoofer amplifier. If the sub amp level setting is low, Audyssey will set a higher subwoofer trim to compensate. If it's too high, and the trim setting is at the end of the range, (i.e, if the range is -12 to +12 and the subwoofer is trim is set to +12, then you need to raise the sub amp's level setting and rerun Audyssey so it can set a trim level that is in range. Similarly, if it's set too low, (i.e, -12), you'll need to turn the sub amp down and rerun Audyssey so it can set a higher trim.
Hope that helps.
Craig
I thought dips were able to be corrected thru EQing while nulls had more to do with placement issues or room problems?
