How to build the F5

Bias

Need a little help trouble shooting. My F5 has been working perfectly. This week I swapped out the PS to increase the capacitance. Now I am having issues being able to bias one channel. PS voltages are at 23V. With the 2K2 resistors at R5 and R6 I can get to about 70mV with zero dc offset; with 4K4 resistors I can get to about 90mV; with 6K8 resistors I can get to about 150mV. I have also swamped 3 different pairs of Mosfets which had no impact. Before I keep increasing the values for R5 and R6 is there something else I should be checking? It seems odd that I would need to increase R5 and R6 resistance (it seems like I would need to go over 10K) when the 2K2 resistors were working fine just a couple days ago.
 
Nevermind! I left Firefox and went to Chrome, started over and it all worked. Order placed. When I get all of this built, I'm going to use the crossover and the two F5 amps to power a pair of 2-way speakers. Experiment between the sound of line level crossover + biamp and traditional passive crossovers in the speakers. A curiosity satisfying project that will keep me occupied for a bit.
 
Another working F5

Last night I finished my F5 build.
Nothing unusual, just a text book build, using everything I learnt from reading the diyaudio forums.

Thank you to the experts, who kindly share their insight.

An even bigger thank you to those who shared mistakes and disasters. Reading about them helped me check my work very very carefully.

My tips:

Remember which end of the soldering end gets hot.

Position the big 0.47 ohm resistors so that you can attach your multimeter hooks, I have them standing off the board a little.

Make very sure that the vairable resistors are dialled down to the minimum.
I measured the 2.21K resistors that are in parallel.
Memorize which way you need to turn the pots.
It could be either way, depending on how you position your pot on the board.

And finally Mr Pass sir, thanks for the design and the posts!
 
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