[sdiy] Polivoks filter principle questions

[julian schmidt]

Hello,

I'm trying to understand the polivoks filter at the moment.
http://m.bareille.free.fr/modular1/vcf_polivoks/polivoks_schem.pdf

so far I understand that it is a 2 pole SVF like topology
In difference to the OTA based SVF where the OTAs only act as integrators,
each UA776 opamp stage is a 1-pole LP filter (internal compensation cap) 
using the gain bandwidth as cutoff frequency.
by varying the gain bandwidth using the Iset pin 8 the gain bandwidth is 
increased/decreased.

Now I wonder what makes the distinctive polivoks sound
http://m.bareille.free.fr/modular1/vcf_polivoks/polivoksVCF@1kHz.gif
look at the harmonics in the resonance.

replacing the opamp integrators with 1-pole OTAs would just result in 
regular 2-pole LP.
Is this due to a frequency dependant saturation happening in the opamp 
when the gain bandwidth is exceeded?

cheers,
julian