Hey everyone,
I've a poweramp pcb that contains a bunch of these SO642 (in a long tailed pair etc).

Now, maybe it's normal but it never happened to me.
Why the datasheet doesn't contains any curves?

The component seem obsolete on most distributors, what would be an alternative?
Shouldn't one also look at the curves to find a good alternative?

thanks

 

You don't always get curves in the datasheet, unless they are particularly impressive.
You have to guess that the maximum beta will be between 10% and 25% of Ic max

I'd suggest 2SC3324 as an alternative, but most transistor manufacturers make an audio-power-amplifier front-end transistor rated at 120V to 150V with good beta and low noise. 2N5551 will probably be pretty good as well.
https://www.mouser.com/datasheet/2/408/2SC3324_datasheet_en_20140301-1150780.pdf
and I bet you don't need 300V Vceo.