![]() Thanks to you and Mojave, I "cracked the code" in the parametric equalizer and I'm in the middle of resetting up and recalibrating my 5.1 system for use with JRiver playback. For the wide band pink noise, regardless of the sample rate, you should filter your pink noise low pass to 20 kHz so all sample rates measure the same level. You're also offering multiple sample rates. Then do similar with the narrow band pink noise. In a perfect room, with the mike exactly in the center, if he turns on left, and then adds right to it, level should go up about 6 dB, for example. Your next set of tones is correlated wideband pink noise so the user can confirm the polarity, frequency-response match, and relative delay of the loudspeakers. If you generate uncorrelated pink noise and give them check boxes to turn on and turn off individual channels they can check that. ![]() Your next set of tones is uncorrelated wideband pink noise so the user can see that the signal goes up about 3 dB as he doubles it, for example, measure left channel, add right, it goes up 3 dB. So your first set of tones should be -20 dBFS wide band pink noise, sent to L, R, C, LFE, etc. Most people do not have a way of muting their individual loudspeakers easily and besides, for bass managed systems, the subwoofers are going to get all the information from all the low pass of all the incoming multichannels so they will be too hot because the user probably cannot mute the incoming signal prior to the bass management filter, if you get my drift. ![]() You need to send the tone to one channel at a time. Your first goal is to give the user a per-channel choice of output. Matt, there's a basic endemic problem with your calibration tones! They come out of all speakers and alll drivers at all times. I think it is reasonable to say that someone with a Rat-Shack meter and uncorrected loudspeakers that are in good shape and a good brand can get within, say, 1 dB of correct if he is careful using the narrow band PN you will be supplying. HOWEVER, and this is a big however, there was a time when my left front loudspeaker was a little low at 400 Hz and a little high at 1 kHz compared to the right speaker, so narrow band pink noise actually produced a greater measurement error than wideband! After convolution correction with Acourate, the interchannel correlation went up so much that these errors have really disappeared.Īs you can see, there are so many potential sources of error that the deeper you dig, the more you have to take into account. Point being that the less confident you are of your system, better to use narrow band pink noise. In the past, I've seen differences of 1 dB or larger. So it's just a confirmation of the adage that the flatter and more extended your system is, the closer the 500-2k will get to the full range. By the way, I meant to report that after accurate convolution/correction with AcourateConvolver, which extended my system to flat below 20 Hz, the measured SPL level difference between full range pink noise at -20 dBFS RMS* and narrow band pink noise 500-2k also set to -20 dBFS is now less than 0.5 dB.
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