This is something I’m also interested in. There’s only a couple of analog VCO’s on the common market that can do through-zero. Doepfer has one, the Intellijel Rubicon (and I’m assuming their soon to be release Rubicon 2) and a new one that’s been teased from hexinverter electronique, called the Mindphaser.

I love analog FM noise, I suspect adding a through-zero module is a next step, but…haven’t gone down that path yet. I asked a question about it here, but it didn’t kick off any conversations. Glad to hear someone else is wondering. Given the Rubicon 2 and the Mindphaser, maybe it’s a soon-to-be-trend?