I have recently get a new job involving service and maintanance of a lot of PA equipment. A lot of really NICE ! equipment I may add. d&b, Crown, QSC, LABGruppen, Chevin, and a lot more
We have a lot of Crown amps, and these sometime get broken despite the good quality, and their reputation of beening able to handle "anything".
Right now there are five amp's (two Crown's) waiting for new output-transistors, and the original Crown-type is rather expensive. Thats why I've been curious in using MJ15024/25 transistors instead.
The question is: How many of each (NPN/PNP) transistors would I need too bee able too match them properly if I use the method described here : http://sound.westhost.com/transistor-matching.htm , and how many categories could I expect ?
Total match is probably out of the question so how big difference would You consider as a good match ?
My thought was to get the best matches, and use the transistors that I can't match in amplifiers that don't need matched outputs (like Studiomaster ++)
Would really appreciate some advice in this matter.