Quote from: galaxiex on November 02, 2015, 07:56:42 PM
Slightly OT...
I actually have one of those Heathkit combo amps (Heath TA-16) that is mentioned in the 2nd post of that thread.
It uses that mix of NPN si and PNP ge transistors in the output stage. TA2577 NPN si, 2N2148 PNP ge.
Most of the designs from the mid to late 60's didn't pay much attention to thermal feedback. Many times the bias diodes weren't mounted on the heatsink. A number of designs just used fixed bias like the Thomas/Vox amps. The Si/Ge designs were an attempt at a complementary output stage using parts that were actually available at reasonable prices.