The fT of mje243/253 is only 40MHz, which is too slow to drive modern audio power transistors that can have ft 30MHz easily.
Although BD139/140 doesn’t specify fT in the datasheet, I feel they are much faster than mje243/253. The weak side is their voltage rating.
Although BD139/140 doesn’t specify fT in the datasheet, I feel they are much faster than mje243/253. The weak side is their voltage rating.