Dear forum members:
I´m new to this site, but not to JBL products which I have been involved with since the late 60´s. Recently I purchased a SA600 and a SA660 amplifier in need of restoring. Now I have scanned this site for info and am sorry if I have missed a thread somewhere, but I´m trying to find out what transistors are used in the output stage of these amplifiers. After looking at hundreds of pictures of SA600 amps on the internet it seems that Q7 and Q8 would be 2N3584 resp 2N6421, and Q9 and Q10 would be MJ15003 and MJ 15004 respectively. Could anybody confirm this? Also, are we using the same devices in the SA660/SE460 amp?
Many years ago I built a copy of the SA600 (I had a SE400 on hand) and I still remember what transistors JBL used in the preamp section. They were 2N4123 (NPN) and 2N4125(PNP) and are actually available today.
Best regards