I did a suboctave comparison with the Iron Ether Subterranea and Subterrograph, the 3 Leaf Audio Octabvre MKII and MKIII, and the Broughton Subsonic. (I don't have an OC-2.) I'll share my thoughts on the two Iron Ether pedals so anyone searching this thread in the future can find them.
As many of you know, the Iron Ether Subterranea has its own suboctave sound. It's not another OC-2 clone. It's somewhat gritty (though not to the level of a COG T-16 or Mu-Tron) and has that characteristic bit of synth bleed on the clean circuit. It's a good sound. A rich sound. I'm glad that it is different from the 3 Leaf and Broughton stuff because that means more options (and fun!) for us bass players.
I hear a difference between my Subterranea and Subterrograph, which is not surprising because I know individual Subterranea sound different. I haven't owned as many examples of Subterraneae--yes, that is the official plural form because I've decided it's a first declension Latin noun--as some of you, but I chat regularly with many of the pedal collectors and enthusiasts who frequent this thread; my impression is that the Subterranea has more variance between individual units than any other Iron Ether pedal. Why? I don't know. Perhaps component differences? The human factor in the build? Small refinements to the circuit over time? This particular Subterranea isn't the first to pass through my hands, but I don't recall the nuances of how my previous Subterranea sounded so I cannot speak to all this myself. I just remember liking it lol.
Anyway, in my comparison of these two particular units, the Subterranea had a brighter character while the Subterrograph sounded warmer and fuller. I vastly prefer the Subterrograph. While the difference is clear and undeniable, I could imagine someone preferring the brighter Subterranea if they wanted a more of certain frequencies in their suboctave and synth tone. It would certainly sit differently in a mix and, depending on that mix, could cut through better.
I'd love to hear from anyone else who A/B'ed both of these. Did you hear the same things as me?