As we said in connection with audio distribution transformers, sound is produced by the overlapping of many sound waves in the air, that is, by many electromagnetic waves within the audio application. The fact that the human ear has, in general, a perception of sound in the range of frequencies, that is, the bandwidth, between 20Hz and 20KHz, with the best perception being between 700Hz and 6KHz, could make us think at a first examination that it is sufficient for an audio application not to introduce distortions in the range 700Hz-6KHz.
These initial evaluations go against the search for the perfect reproduction of sound, obtained with audio applications of the highest quality (high-end), where every detail from the valve to the individual components and wiring is carefully looked after so as to avoid the presence of the slightest disturbance or distortion even well beyond the range of audible frequencies. This obliges TECA to design and produce coupling audio valve transformers which follow the above philosophy without worrying about economic dictates.
When designing and producing these transformers, TECA takes into account not only the classic design parameters, that is performance, reliability, quality and safety, but it also pays particular attention to testing perfect linearity within the bandwidth, and to the attenuation of the signal at –3dB which must take place at frequencies well beyond the cut-off frequency of the transformer (at least 10 times greater). In this way the signal transmitted by the final amplifier to the acustic transductor is perfect, even to the most demanding ear.
These results are made possible by the particular full-custom design based on three main aspects:
the choice of magnetic material for the core, using components with high permeability and characteristics which differ depending on the frequency, which adapt perfectly to the elaboration of complex signals;
the pairing of the core and the copper of the windings, chosen so as to select the dimensions and form of the core that optimize the successive position of the windings;
the single windings, suitably subdivided and wound onto each other and paired so as to obtain the values required for resistance, current and voltage, and to reach the electromagnetic performance required.
The field of high fidelity is in continuous evolution and so TECA’s models are constantly being developed thanks to the use of new technologies, new winding and testing techniques, at the same time researching new materials which allow the performance of TECA’s tube output transformer series to be further improved.