Had a chance to record an occluded mechanical grinder throughout our buildings twelve stories. One of the most interesting sounds was in the stairwell, walking up and down each floor was like adjusting the wet / dry mix.
Over 45 minutes of audio was edited using different mics and perspectives. How to turn an awful sound into library 101. Here are some samples of the recording to download.
Mono 24bit / 96KHz
Rode NT4, NTG3