- This PCB is projected to put heatsink at bottom site of PCB, connected with both FETs.

- Adjust VR3 to get around 4 volts on pin 9. Try to adjust mearuring power drained. Start with 3v and incrase until power drained start to increase too.

- Low value cap filter after inductor can cause IRS protection activation and more output noise (but not noticeable at speakers). Prefer to use more cap as you can for the frequency response you want.

- 30uH inductor with 3uF filter provide good stability, power and noise reduction, for frequency response up to 12kHz or more.

- IRS easily active protection overcurrent if not correct calculate resistors of pin 8 and pin 16. When increasing volume, protection was activating with less then half of power I want. I got to fix it with R2, R3, R9 and R10 resistor value used in this schema, increasing output filter cap from 470nF to 2.7 uF, and adjusting Zenner resistors to stabilyze pin 1 and 6 with at least 5,0v in idle (amp on).

- 12v bias from -B need to be strong enough. ICs and FETs uses a lot of current. An good solution is to invert Bias Transistor to bottom side of PCB (like doing with FETs), and fix them in the same heatsink.

- Using IRFB4227 or IRFB4115 can run amp with more than 80W with no heatsink. Mosfets with this gate resistors values (10R), and 140kHz modulation, provides no heat dissipation on idle, when correctly adjusted deat time. I got more than 300W with no problem.

- Zenner resistors (R4 and R6) need to be defined according to power supply voltage. Reduce for lower value if using less then 50v+50v. Test when circuit is complete with all components, to get not less then 5v on pin 1 and pin 6 (reffered to ground) in idle.

- Increase R2 resistor (Vref) and redude R3 to activate overcurrent protection with less power. With actual values it is disabled. On my tests, 0,4v on pin 8 (from -B) activate OC procetcion wth small power, and with 0,65v protection no more is activated.

- Power tests with 80 Hz sine wave, 140kHz frequency modulation:

   - Test 1: I got 390W @ 4 Ohms, 59v+59v output power supply. After 5 minutes at full power, IRS2092 reach 60ºC, inductor 70ºC, and FETs 70ºC with this small heatsink without fan.

   - Test 2: I got 480W @ 3 Ohms, 58v+58v output power supply. This small heatsink is not enought to support this power for more than 4 minutes.

By add heatsink to IRS, and fan direct to board and FET heatsink, can probably solve temperature problem to use at full power (400W+) for several minutes.

Limit power for this board and configuration (IRFB4115 and 140kHz switch) probably can be reached with 70v+70v power supply, using 4 or maybee 3 ohms output load.