solid-state Bass amp

[unclejed613]

i once replaced 2N3055's with MJ15022's in a bass amp i had. it didn't change the sound of the amp at all, but did give a slightly better margin on the Safe Operating Area of the transistors. i was fortunate to have some transistors whose beta figures were all below 40. you might want to turn down the bias a bit or beta match new transistors to match the old ones as the MJ1502x series transistors average a higher beta than 2N3055's do. also, you might want to check the amp for oscillation, since Miller capacitance may be higher.

also... in regards to the second part of your question NO!!!!! and no.
PNP devices are of the opposite polarity, and will short before the power supply caps finish charging, then there's all the fire and smoke to deal with.... (or at the very least a blown fuse).

mosfets use much higher bias, and requires some major changes in the driver stage, and may require changes in other parts of the amp as well. definitely not for newbies.....