Hi, I'm using the APEX PA84S power opamp in a simple inverting configuration with a gain of 30 (R2=300kOhm, R1=10kOhm). I used it successfully for driving a MEMS device (*very* small capacitive load) from 0-150V in 1 microsecond and used this opamp specifically for its high spec'd slew rate (~200 V/us). The rails were biased at + and - 150V using an Acopian dual regulated supply. I wanted to use it again with the same power supply, but this time at 0 V at the lower rail and +300 V at the upper rail. This is pretty easy to hook up with the power supply by grounding the minus terminal of second supply and tying the plus terminal to the minus terminal of the first supply; with the plus terminal of the first supply being +Vs. Overall, things work, however, the slew rate with the new rails is now around 15 V/us, about 10 times slower. Playing with the compensation resistor and capacitor values did not seem to change anything (which was somewhat a surprise), nor did changing out the R1 and R2 to have different values (maintaining and varying the gain). Does anyone know why the slew rate suddenly dropped with this configuration and how to bring it back up if possible? I was hoping this would be an easy problem. The power supply can source 100 mA according to its data sheet which should be more than enough for the opamp (according to its data sheet). The voltage terminals at the power supply have been checked using a voltmeter and offset trimpot specified by the datasheet (50 kOhm) is being used. Bringing back the power supply to a bipolar configuration (+/- 150V) showed that the opamp was still good so the opamp did not die. Any suggestions would be appreciated!