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Where did you get your electrical engineering degree?

Your statements are ludicrous and sound like you memorized them from ad copy written by some apologist for tube amplifiers trying to justify this antiquated design. What are the facts? Harmonic distortion of typical solid state amplifiers remains extremely low right across the audible frequency spectrum. There is no comparison in the non linear distortion levels running typically 0.1 to 0.2% or better for a solid state amplifiers up to 20 khz and the 1% to 2% distortion or more of vacuum tube power amplifier circuits. High damping factors are not needed at high frequencies. Dynamic damping also called dynamic braking is the amplifier's ability to shunt reverse emf generated by heavy mechanical loads such as woofer cones having high inertial mass and momentum preventing them from moving out of conformance to the applied electrical voltage. Midrange and tweeter cones don't have nearly enough inertial mass or momentum to present a problem even for poorly damped amplifiers. Negative feedback is NOT a crutch for bad design. It is a way to improve performance of analog circuts resulting in extending and flattening frequency response, reducing non linear distortion, and increasing stability. Admittedly the equations are extremely complicated to apply and difficult to understand even for many electrical engineers and can lead to bad consequences when misapplied but the basic principles of negative feedback are the very foundation for all modern control system theory. Were it not for negative feedback, you couldn't even steer your car where you want it to go.

I've had some experience with laminated magnetic cores. The biggest problem with them are losses do to circulating eddy currents which turn the magnetic flux directly into heat inside the lamina (which is why they are always made thin) and even worse IMO hystresis losses. In this type of loss, the response of the output of the transformer is distorted every time the magnetic field changes polarity which is every half cycle. At the smallest signal levels it is extremely non linear having to overcome the resistance to reorienting the magnetic domains. The magnetization/demagnetization curve where the induced field is measured against the applied field does not retrace itself due to this resistance to magnetization. The area between the curves for a full cycle is the hystersis loss and the best we have so far is from transformer iron made from permalloy and supermalloy which saturate at about 15,000 gauss. Inefficiency for transformers runs about 2.5% to 5% and the curve flattens at the extremes where the core saturates. You also have a very heavy inductive series element in the output circuit which may also help explain the perceived high freqency rolloff of many of them. The 1 watt frequency response graphs don't show this and they don't show the effects of core saturation either which is clipping just as hard as any transistor. How any engineer can justify installing one of these in an audio circuit and say with a straight face that he has created a first rate amplifier is beyond me.

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