Should I be interested in something else than TPT/ZDF filters at this point of time?

[Z1202]

The one feature that makes ladders worth learning about (after the SVF) is that they are pretty stable to higher orders, which is rather convenient if you're stuck with a high-order transfer function and would prefer not to root-find for biquad decomposition. Converting from direct to ladder form is numerically less than ideal, but still potentially much better than root-finding and the stability condition is trivial (all reflection coefficients less than unit magnitude).

Actually, I tried higher-order TPT SVFs (without factoring into biquads) and they seemed to work fine numerically. Not sure what was the order, at least 4, possibly 8. So I'm not sure what's the source of the idea that higher-order SVFs need to be factored. DFs are a totally different story.

[mystran]

The one feature that makes ladders worth learning about (after the SVF) is that they are pretty stable to higher orders, which is rather convenient if you're stuck with a high-order transfer function and would prefer not to root-find for biquad decomposition. Converting from direct to ladder form is numerically less than ideal, but still potentially much better than root-finding and the stability condition is trivial (all reflection coefficients less than unit magnitude).

Actually, I tried higher-order TPT SVFs (without factoring into biquads) and they seemed to work fine numerically. Not sure what was the order, at least 4, possibly 8. So I'm not sure what's the source of the idea that higher-order SVFs need to be factored. DFs are a totally different story.

I should probably have said lattice rather than ladder, 'cos it was lattice-ladders that I was talking about. By "high order" I mean like order 128 or something.