Audio sample rates and bit depth.

Author	Message
PhenixRising Guru Joined: 07/11/2023 Location: United Kingdom Posts: 1996	Posted: 12:36pm 30 May 2026         Martin H. said   Before AI came along, we used to remove the vocals from songs to create backing tracks. As the vocals are usually positioned right in the centre of the stereo recording, they are equally loud on both sides. We’d invert one of the stereo channels and then mix it into the other channel. Sure, there are lots of apps like this one and they are quite amazing. Personally, I am not satisfied with the results and so I load them into a DAW (digital audio workstation) as separate tracks and replace them one at a time. The interesting thing about the video, for me, is the fact that they demonstrate that a higher sampling rate doesn't mean "better". I have the same beef with servo-motion-control; many years ago, it was established that a 1KHz PID sample-time was the sweet-spot and of course, AI agrees, only because it has become a belief. My real-world experiments don't agree. What puzzled me is that;   Quote   For example, audio CDs have a sampling rate of 44100 samples/second. At 0.5 cycle/sample, the corresponding Nyquist frequency is 22050 cycles/second (Hz). Conversely, the Nyquist rate for sampling a 22050 Hz signal is 44100 However, for a closed-loop servomotor, they recommend five to ten times the bandwidth of the motor. Not the Nyquist two-times. The definition of bandwidth is the time taken to reach ~63% of maximum velocity. So if a 3000RPM motor can achieve 1800RPM in 0.01 seconds, it has a bandwidth of 100Hz. Therefore, "ten times the bandwidth" means a 1KHz PID sample rate. In my world, a small motor is 1HP and it is mechanically coupled via belts or ball-screws or gear reducers to a load that has inertia/friction/stiction, etc. (mechanical LPF). So in my case and the majority of cases, the numbers are overkill. They waste processing power and I have found that lowering the sample-rate to 500Hz and 250Hz loses no performance and seems to result is easier loop tuning (only a feeling at this point). Over the years, I have read countless publications pertaining to PID motor control but I am starting to suspect that many of these "authors" have never had actual experience with a real motor and are merely parroting/plagiarizing.