Why is impedance mismatching so dangerous?
The crux of the problem lies in the inductive nature of the output tranny. Inductive loads are pretty special things, since they STORE energy in a magnetic field. A property of this effect, as has been pointed out, is that the voltage can soar to levels above the supply voltage in the amplifier– sometimes WAY above. You can’t do that with any other kind of load other than inductive. Now the transformer doesn’t have an impedance of its own; it only reflects an impedance from one winding to another in proportion to the turns (or voltage– they are the same) ratio squared. So imagine that you’ve got an open secondary. This impedance is for all intents and purposes infinite. Thus, regardless of the turns ratio, the primary impedance is infinite as well. (leakage inductance and parasitic capacitance– two unavoidable nasties of real-world trannies– will limit this to some finite number less than infinity, but suffice it to say its really high.) This means that the primary will act like a
