NTE has a Cross Reference Search that cross references to (what else?) NTE components. The NTE cross reference is pretty general; crossing the BC558 brings up the NTE159. Crossing both the 2N2907 and the 2N3906, which I would not consider to be crosses of one another, brings up the NTE159.
When I need to cross reference a transistor for an audio circuit I search for a transistor the same or higher breakdown voltage, current rating, similar beta, and the same package.
NTE159 and 2N3906 are both PNP, but 2N2222 is a NPN, so could not cross to NTE159. Also worth noting, a 2N2222 has emitter and collector leads switched from the usual configuration (unlike the PN2222),, a fact that has bitten me more than once!
Dave; looked up the TCE crosses. Ref SK......s. Is there a 'better than close' sub guide(s) avaliable? Where do the 'B' series originate?
Message was edited by: SHANACO
Many years ago I had a book that cross referenced thousands of transistors and it might have been the Howard W. Sams book. Amazon.com has several transistor substitution books.
This Wikipedia article on transistors sheds some light on the part numbering conventions. The only comment about letter sufixes is "A letter suffix (such as "A") is sometimes used to indicate a newer variant, but rarely gain groupings."