The most common phono ‘pickup’ or ‘cartridge’ is the moving-magnet type and the vast majority of phono preamplifiers are designed for their relatively high output voltage … generally about 5 millivolts (at standard stylus velocity of 5 cm/sec). However, extremely high-performance moving-coil pickups are preferred by many audiophiles. These pickups have extremely low output voltage … most often in the 0.1 to 0.5 mV range … and a correspondingly low impedance … most often in the 5 to 50 Ω range. It is extremely difficult to design amplifiers for these pickups that have acceptably low noise floor. Therefore, step-up transformers are commonly used to provide essentially “noiseless” gain to these tiny signals. The benefit is a very low noise floor. Of course, preserving audio quality (low distortion and wide bandwidth) is very important … and why you should consider Jensen.
Posted in: Transformers