On the digital filter issue here is what can happen: lets say you are feeding the ADC in the recording studio an analog waveform in which the peaks are exactly at the level to produce a Full Scale (FS) output. What happens when a sharp peak (say a piano key pressed hard) hits inbetween the sample points? The numbers that come out of the ADC are slightly less than FS, the sample time hits the "skirts" rather than the peak. When these samples are fed to a DAC the digital filter inside reconstructs the peak inbetween the original sample points at exactly FS, the DAC handles that correctly and everything is fine.
But what frequently happens is the track gets processed and those samples which were slightly below FS now get boosted so they are at exactly FS. When THESE samples hit the digital filter in the DAC it now produces a peak which is greater than FS. There are a few different ways a DAC can deal with this. If it was not specifically designed to deal with this issue that peak above FS will most likely wrap around and become a FS peak of the opposite polarity, a short impulse as loud as the DAC can produce, a REALLY REALLY bad distortion! It can clip the value, this is not as bad since it is just chopping off the very peak of the waveform, OR it can decrease the volume of the whole waveform very slightly so it can properly reproduce these peaks above FS. The last option seems like a good way to deal with it, BUT the chip makers don't like doing this, it means everything is slightly lower in amplitude which decreases the overall SN ratio of the chip, and to a chip maker that is the single most important spec to get as good as possible. Doing this to one of their chips puts it at a disadvantage in the marketplace. If every chip on the planet did this and did it by the same amount, then it probably would not be an issue. But then you would have massive creative specmanship going on. John S. ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=97483 _______________________________________________ Touch mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/touch
