----a 10pf caps need to be solder directly on R5 ,
----a NP capacitor 220uF 50vdc is raccomended on C1
----RB TRIMMER is otionals , NO install !!
bias setting : for first setup install a trimmer 200k instead R11 , start to a 20k value and turn the trimmer for your best value bias setting then replacemente with a fix value.
the Heatsink run very hot , for this amplifier need a very large heatsink ...four unit dissipation cabinet.