tomp wrote:
As I have mentioned before you must be cautious about differences just by adding a super tweeter due to possible interactions between the regular tweeter and super tweeter than can fold back into the "normal" high frequency range.
We do not know how our auditory system works in real life. Here is another of my post from 2001.
Psychoacoustics is based on very simple and straight forward observations and facts. I have no doubt about the perception of 17-20kHz freqs in "absolute" sense when measured with pure sinewave tones. And ofcourse, we have JNDs too based on again, pure sinewave tones. Then those who would argue, transmission of high frequencies in bones, middle-ear, cochlea excitation etc, to determine if they reach our brain.
There is lot of good science in psychoacoustics, which should be used to understand the human complex ear-brain perspective mechanisms as a whole. Instead, many in the psychoacoustics field adopt the easier the "divide and rule" principle. Unfortunately, these finite divisions have do not give realistic understanding of our hearing perceptions. For example, we can perceive 1/30th of the JND thresholds when subjected to dynamic content which music is. Similarly, most of us cant hear above 15kHz, yet we can immediately perceive the difference between tweeter with FFRs of 15 and 20kHz. Same can be said for ultra-sonic frequencies, based upon my readings and intereaction with credible sources.Quote:
Also the comments about brickwall filters which I think have merit are rather moot nowdays as most DACs automatically oversample to much higher rates, not to add information which they cannot do but rather to eliminate the need for brickwall filters.
Tom, the brickwall filter is applied in the CD source material. No amount of upsampling during playback can change it.
Nyquist theorem states a minimum of twice the max frequency is needed to accurately represent the waveform. Redbook has the max frequency of 44.1kHz, which means it can represent max of 22.05kHz. Amy material above 22.05kHz in redbook standard becomes noise, hence the brickwall.
Upsampling reduces the noise levels by raising the dB level of the source material, each bit represents 6dB, it does nothing to the fidelity.