[sdiy] CEM3372 passband gain trick?

[Lanterman, Aaron]

Looking over the CEM3372 VCF datasheet, this line caught my eye:

"A unique feature of the 24db/octave filter is that, unlike others of this type, the passband gain reminds constant as the amount of resonance is varied, this eliminating the annoying drop in volume at higher resonance settings."

Any ideas how the CEM3372 pulls that off?

- Aaron

P.S. What does "VCF Uses Open Loop Design for Enhanced Sound Richness" mean?