An MJE1503x's are CHEAP so I don't see what the big deal is.Īn EF3 would be possible using the 3055/2955 complementary. People always bash 3055's about poor SOA and that's not really the problem. Which is why you want 3 in parallel, use an 8A driver, and a triple in the first place. But they are also a 25A part that has typical hFE of 20-ish at 25A, and totally not like the 3055 which has a typical hFE of 7 at 10A.

The MJ802/4502 tend to be better matched than most but that was really dumb luck not something they did specifically when they were designed. The NPN and PNP from most 'complementary pairs' of power transistors aren't very well matched. A decent model will help get out major problems, assess stabillity, compare topologies, etc. There are too many other things about the circuit, the layout, and the components that are NOT modeled and have a huge impact on whether you can get to. I use simulators as a guideline - I never take the results as gospel. I have tried with their MJ2955 model and the one for the 2N3055H, but this doesn't seem well matched. They have 3 different models for the 3055 in sp3 format, one of them not correct, because it's for a darlington, a different beast, and they call it a 2N3055A. The models available on onsemi's site are rather old (2004), but they may be recent enough if nothing has changed further since. However I was trying to find an MJ2955 that could match it, and it seems nothing I have found so far is correct. That model works well and I have used it on quasi complementary amps with no problems. Using LTSpice, there is no 2955 in its parts database and I suspect the 2N3055 that comes in its database must be rather recent, but we don't know where it came from and what parts it corresponds to. I would like to find recent models for the fast types manufactured now.

There has been so many variants of the 3055 and the other flavors of the 2955, it's hard to find models that match for both the npn and pnp. I know this thread has been dead for more than 10 years, but I couldn't find decent models that work properly together.

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