Can anyone tell me why is this stage causing distortion?

[slow_rider]

So I have this circuit on a board and when I set the gain of the 2nd stage to anything but ~1 I start getting distortion. I've hooked up a signal generator with a 0.4Vppk 1KHz signal and could see it goes in clean and is still clean before entering the 2nd stage, as I increase the value of the feedback the resistor the Sine wave starts looking like it has a bunch of added harmonics (I can take pictures from my scope if needed). Why is that? The headroom on the supplies is almost 18V and the max. amplitude amplified by a factor of 3 would give a signal very small compared to that. On the simulation everything works as should.

Any thoughts?

* Voltage rails where checked.

[T3sl4co1l]

There's no resistor to U1A +in.

Resistor values are also rather large for a 5532.  A JFET amp like TL072, LF412, etc. would be better suited here.

Tim

[mij59]

Pin 3 of the U1A is floating for dc, no bias current can flow, connect a resistor between pin 3 and gnd.

[slow_rider]

That is true! Thanks!

I'll see if I have a 1M resistor somewhere...

[rjeberhardt]

Your 400 mH inductor combined with the two 0.1 uF capacitors is giving you a series resonant circuit, resonant at about 1 kHz.  So, when the two variable resistors are at or near zero you will get a much magnified signal at the input of the second OPamp and overload it.

Russell.