In algorithm "tremolo rack" for example, how do you sync the rate to midi clock?
is it that some algos don't support sync?
I took a look at that algorithm (3038) and you are correct, it doesn't implement a midiclock input, so it won't sync. As you probably know, all the algorithms in the H9000 that are numbered less than 9000 come from the H8000FW and previous rack products, and were written by many people over many years, so they aren't very consistent. It's possible that there's another algorithm that will do what you want. I expect it wouldn't be too hard to add midiclock to that algorithm either, but I can't promise that at the moment.