Has anyone actually ever used the ST (Straight Tip) connection?

I was considering using a ST-TOSLINK cable... but that does not work.
ST is using 820nm wavelength while Toslink is 650nm (the red light).

That would have been connected to a fancy/high-end DAC maybe?

Julien

Is that connector a standard ST fiber optic one? If so, I wonder if 820nm is a/the standard wavelength used with some (or all) ST-era fiber equipment?

If both of the above are "yes", then I have a couple of ideas of how to use that signal potentially. (I should look this stuff up.)

Edit: Yes, the X0's connector is a standard ST one (I had not heard the term "straight tip" before), and 820nm is a common wavelength over multimode fiber (likely what the X0 accepts). And, since it is adjacent to the Toslink and coaxial connectors, it is probably the same data stream. So, finding or building a media converter may not be super-hard.

Only found super high-end/expensive 80's/90's DACs with ST inputs:

https://audio-database.com/TEAC-ESOTERIC/etc/d-30.html
https://www.stereophile.com/content/theta-ds-pro-generation-v-digital-processor
https://www.stereophile.com/content/sonic-frontiers-sfd-2-da-processor-rh-sfd-2-mkii
https://parasound.com/pages/vintage-units?#DAC2000%20Ultra_specs

Julien

That does not surprise me at all. The HLD-X0 and related MUSE equipment was highly expensive when it was sold new, too.

It is truly funny reading all of that overkill gibberish about "jitter" and "0.5 Hz" and so on, in the description of one of those processors you listed.

My thoughts about "media converters" were more in the range of what "optical/Toslink-to-coaxial converters" do. I live thoroughly in the "digital data is digital data" world/mindset, so I was thinking of just going from 820nm to coaxial, then into your/anyone's same device that was using Toslink or coaxial before. Essentially, a "just for fun" project.

I do not want to download the whole HLD-X0's service manual if it is available here (and use all of that data/bandwidth that you are paying for, thank you!), just to see the schematic diagram of the digital-outputs board(s), but maybe I can find just the diagram online.