# Diagnosing not-working filter circuits

I'm trying to build a state variable filter, to this circuit diagram:

All resistors are $1k\Omega$ and both capacitors $1\mu F$.

I've constructed it on a breadboard:

But the output I get, ignoring some distortion when the input is loud, is the same as the input, no filtering is done at all. I have tried powering the opamps with both a 9v battery and a +12v/-12v power supply, and still, the output is the same as the input. (I have of course done the calculations on the circuit and the output should definitely not be the same as the input). The opamps seem to be working (they're getting power and the + and - inputs are at the same voltage).

How can I diagnose this? I do not know where to start.

• start with a frequency sweep measuring amplitudes at each output. Aug 9 '15 at 11:06
• Do you have the ground point shown on the schematic at centre rail? Aug 9 '15 at 11:48
• @Andyaka as in connected to the centre (0v) of the -12/+12v power supply? Yes Aug 9 '15 at 17:13
• Another good tool is LTSpice available for free. Consider simulating the circuit with that and ensuring it is not a design problem vs an implementation problem. Aug 9 '15 at 21:45