Jupiter 6 filter resonance gain

When I first simulated the jupiter filter, I had made a mistake. I forgot to connect a 33k resistor from the negative terminal of the resonance OTA and to the filter input. I didn't notice, and all my plots looked good. More than that - I actually could add resonance without the lower frequencies getting attenuated. Reading up on state variable filters today indicates that this is a feature of this filter topology (http://sound.whsites.net/articles/state-variable.htm)

When I corrected this error though, to my great surprise, lower frequencies got heavily attenuated once resonance went up!

I have checked and rechecked and traced the original JP6 PCB but I always come to the same conclusion - the resistor is there.

I even went back and simulated the filter with and without the resistor, looking at both filter response and phase, and honestly, I can't see ANY difference, except for the attenuation.

Zero resonance without resistor

Zero resonance with resistor

Max resonance without resistor, same low frequency gain as no resonance

Max resonance with resistor. gain has fallen by 24dB

This begs the question: What is the purpose of this resistor/line?

Right now my only two conclusions are either that it is there to attenuate lower frequencies on purpose - exactly the thing other filter designers fight to. Or LTspice simulates the circuit incorrectly.

I guess won't get an answer to the last question until I breadboard the circuit.

Update: Scott Bernardi made a comment about the attenutation here: http://www.bernacomp.com/elec/og2/og3_4pmultimode.html - Without it the resonance would start clipping (depending on the rest of the circuit of course). That makes sense.