For what it's worth, as someone who spent many a school holiday watching (and listening to) Vulcan 1s engine running on the de-tuners, I do not recall that sound from the Olympus 100 series. Many years ago, I was told by a, sadly now late, departed, member (Alan C) of BAe's XM603 Club that the Vulcan displayers preferred the OLY 201s because of their distinctive sound. Their own 301 powered machine did not produce it. Something to do with cropped compressor blades, as I remember it.