Re: Impedance matching question

Dale H. Cook

At 09:58 AM 3/26/2019, Craig Sawyers wrote:

Going way back long distance telegraph and telephone lines were significant fractions of an audio wavelength in the cables, and they needed to impedance match.
Through the tube era and the discrete solid state era professional balanced audio lines in radio and recording studios were also impedance matched at 600 ohms (earlier 500 ohms) because they were transformer coupled and power sourced. The constant impedance was implemented for maximum power transfer. It was not until the advent of high quality op amps that voltage sourced balanced audio lines became the norm in studios.

Dale H. Cook, Radio Contract Engineer, Roanoke/Lynchburg, VA

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