The objective of linear power amplification is well recognized by professional audio amplifiers: the shape of the electrical voltage at the input should appear proportionately larger at the output - any deviation is distortion.
If a loudspeaker (dynamic transducer) is connected to a power amplifier carrying the audio signal, an exchange of electric currents begins, because of the loudspeaker as a linear motor develops an electromotive force which makes it appear as a generator or voltage source. These voltages generated periodically by the loudspeaker and the corresponding currents flowing back into the amplifier are, by design, deformed to a greater or lesser extent by linear and nonlinear distortions. In order to achieve the above-mentioned goal of linear power amplification, the regulation of the power amplifier must be able to suppress the loudspeaker electrical audio signals and their linear and non-linear distortions.
Based on measurements with linear and non-linear loads and based on listening tests of different power amplifiers, the output resistance has proved to be a critical parameter: it should be as low as possible over the entire frequency response. With regard to the quality of the bass reproduction, this is no new insight. What is new, however, is the importance of this parameter for the clearly audible distortion in the mid-high range and in the wide range of sonic micro- and macro dynamics, contour, plasticity, and spatial impression in the whole spectrum.
In particular for high frequencies and for large signals, the requirement of the lowest possible output resistance of the audio amplifier enforces the most efficient control, the technical feature of which is a high GBP gain-bandwidth product. The HGBT high-gain bandwidth technology of the SE-PA-100 is a particularly powerful control technology for very low output resistance, very low distortion and very low noise. In fact, the power bandwidth of the SE-PA-100 is 1.7 MHz, limited only by an input filter to 5 Hz - 130 KHz (-3 dB).