Originally Posted by k_lewis
I had a phone call with JB about setting up the channel balances manually - He said to not use the internal pink noise generator, it is not accurate and is a normal issue with onboard noise generators.
Well, most internal noise generators are accurate, if the product was certified by Dolby. There may be products that activate the noise with the EQ bypassed, and that then is inaccurate because it does not reflect actual playback conditions.
The proper method for channel balancing is to use the AIX setup disc with reference level tones, and a DB meter set to A weighting / slow response, you want to adjust all to 75dba.
The AIX test signals are not suitable for a 75 dB calibration like most other test discs. In my calibrated system they measure almost 10 dB higher -- 83 dB. Of course it will do no harm to set them to 75 dB, but "ref level" on the volume control will not be anywhere close to ref SPL.
I don;t like the AIX test disc tones though with how they are set up.
I would prefer it if each channel tone were it's own track number. you could then set track repeat and have it loop that track until you are done, then you can manually skip to next track and channel, etc. - there are other test tone discs out there set up in this separate track manner, and I don't see why you could not use one of them as long as the tones are consistent. All we are doing here is ensuring each channel's volume at the speaker is consistent to the FL channel.
For all these reasons, plus the uncertainty as to what levels are actually printed on the AIX disc, I highly recommend the Spears&Munsil 2nd Edition BD. The noise signals are properly bandlimited, and spot on for a 75 dB SPL calibration (including subwoofer). And it's easy to park the signal on any channel you like.
Originally Posted by Steve Bruzonsky
C weighting, not A weighting, for the decibelt meter. A is fast, C is slow!!!@@@
No, A and C are frequency weighting curves. Slow/Fast is a separate selection that can be applied to either curve.
It's a good idea to use A/Slow for comparing relative
channel levels if one must use the AIX disc, as this will reduce SPL errors caused by bass variations. But it's still not certain what is the correct target SPL for AIX, and using that for a subwoofer cal is another can of worms. Much better to use a known quantity as mentioned above. And **if** the product is designed right, there's no reason you cannot use the internal cal tones and get proper results. One way to see if that's true -- compare the results with the S&M test disc.