Is this biquad circuit OK?

[Jidis]

Per Abbey Road's recommendation, I threw together a simple state variable biquad to mess around with. The only thing close to a usable output seems to be from the LP tap from the third amp stage, but I'm not sure exactly what range it's passing. I'm simultaneously trying to get my head around LTSpice so I can try out different part values to see what they'll do, as well as figuring out what ranges the outputs on this thing should be giving me.

The circuit looks pretty similar to one I tracked down in someone's app note, but if anyone sees any major flaw in it, please let me know. I'm using a quad chip (TL084) which is socketed, so I've been able to check all paths and values a couple times and they all match the schematic. It came from here.

Thanks!

 

[Jidis]

Don't seem to be able to delete this thread, but I think I'm straight on the filter now. I think those listed values just had it at some crazy range that did me no good. The cap/resistor changes they listed for a 1k center frequency made it sound about right.

Off to battle with LTSpice now.