I’m trying out my new TO-3 to TO-3P adapters on this Marantz 1060 that’s been sitting around my shop, 90% complete for the last few years. They look so cool!

I think these Sanken 2SC4468’s —that I found in my junk bin— are going to be a better fit for the 1060 than the usually recommended ON Semi MJ21194. The MJ21194 is a super high-power device, 250W, with a big 5.5mm die, and big Cob and Cib to go along with it. And only 4MHz. (Minimum spec, it’s probably more like 10MHz) The original Hitachi 2SC897’s are only 60W, with a much smaller die, and low Cob. This is only a 30WPC amp, so why use a 250W transistor? The Sanken 2SC4468 is 100W, 250pF Cob, and its 20MHz Ft is a closer match to the 15Mhz of the 2SC897.

The 1060 is a well-compensated amplifier, I’m not too worried that it will oscillate with these slightly faster transistors. But I have yet to actually test it, this amp still needs work!

This is so cool, the selection of transistors that could be fitted is vast! Not just MJ2119X. Pick the best transistor for the job. And soldered to an adapter, even better thermal performance! (I’ll be doing experiments to test this assertion soon.)

Update 2024.04.20

Changed my mind! ST 2SD1047 instead. Even lower Cob, 150pF… If I’m going to test the concept of using lower capacitance devices in the 1060, well these are even lower.