Em Tue, 2014-03-18 às 19:52 +0000, Fons Adriaensen escreveu: > On Tue, Mar 18, 2014 at 03:32:55PM -0300, Iain Mott wrote: > > > Thanks a lot Fons. When I pan pink noise with at W at -20dBFS RMS, the > > individual X and Y channels peak at about 3dB higher. Is that why you > > said to meter at 86dB and not 83? > > No. In a stereo system, with the levels as 0dB on the K-20 meter, each > speaker produces 83 dB SPL. Assuming the signals are mostly decorrelated, > the total level will be 86 dB. So the 'reference SPL' is 86 dB. >
OK - I see what you intended. > > For my current purposes, I'd like to reproduce as best as possible, > > ambiental b-format recordings over an array of speakers - and preferably > > try to match SPL measurements taken at each recording location. Do you > > think the formula above would be correct to match levels in this way? > > ie. if I make a recording at a site where the SPL is 70dB, during > > playback I meter this material (the W channel) at -13dB RMS on a k-20 > > meter, and in the case of a 14 channel system, calibrate each speaker > > channel at 71.5dB SPL (x = 83 - 10log14). > > Your only chance to get this right is to calibrate *via the decoder*. > If you follow the procedure I explained, then 0 dB on the K-20 meter > for W will corresponds to 86 dB SPL, no matter how the sound is > distributed over the speakers. That's assuming you don't pan two > or more strongly correlated signals to different directions (if you > do that the result is no longer really Ambisonic). I now understand that W in the metering has a direct relationship to the total audio output of the array - no matter what the configuration - but sorry, I'm still in doubt as to how to go about adjusting the speaker output levels. I initially assumed that during the panning of the signal and the output adjustment, the speaker that is most in focus (at the peak level) would be soloed - but this wouldn't work because it wouldn't factor in the additional output from the other channels. Are you suggesting that all channels should be left open and the system tuned in a number of passes? Dare I say it: might the "-10 log (N)" level be a good starting point for each channel? Thanks _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
