I found the following quote on another forum and wonder what people here think of it. It was taken from a thread where they were arguing whether it was more accurate to use internal test tones or tones froma disc like Avia....I'm of the school of thought that a test disc such as Avia or VideoEssentials is the best way to calibrate, as it's coming from the exact machine you'll be doing most of your viewing on, i.e. the DVD player!
--------------------------------------------------- Quote- That makes perfect sense when the signals are analog. But these test tones are all recorded in Dolby Digital, so they don't exist as PCM until they reach the decoder chip. There's nothing that your DVD player can do to in any way to alter or affect those signal levels. All it can do is not play them, or play them perfectly.
That same chip is where the internal noise is generated, so there's nothing about the external signals that's any better or worse, assuming they have the same frequency spectrum. Some noise signals have a wider bandwidth, like th THX Optimode signals, and these will sound and measure differently in most cases. They will be wrong if they measure differently, because it only means the various speakers are not identical in response.
Dolby makes sure the internal noise is calibrated in level and meets certain spectral requirements.
------------------ Roger Dressler Dolby Laboratories ---------------------------------------------UnQuote This is contrary to everything I have been told.
