Motorola transistors

. . . but you probabaly won't hear any big difference by changing output devices from one revision to another. The main thing is to make sure that the bias is correctly.

. . . and actually newer, better, and more closely matched out of the box than the 15022/15023 is the ON Semi MJ21195 (PNP) and MJ21196 (NPN). Currently, I'm in the middle of totally rebuilding a Threshold Stasis 2 using these.

Lot's of good info in this area at http://www.diyaudio.com

Thanks Cford. I had read that it was a direct swap but what you say makes me question it. I think I'll stick with what I got until it blows and based on the reputation of these power transistors, it should be a long long time...

The actual part #'s are MJ15......
The MJ15003/4 are 20A, 150V, 25 min hfe, Ft = 2Mhz
The MJ15022/3 are 16A, 200V, 15 min hfe, Ft = 4 Mhz

It will depend on the actual amp design as to whether or not this swap will even work, much less give an improvement.

Motorola Semiconductor was split into two companies a few years back. Freescale Semiconductor designs/builds/markets the more complex semiconductors such as microprocessors, DSP's sensors, RF circuits etc. I work for Freescale.

ON Semiconductor sells the discrete product line.