Richard Lee’s Ultra-Low Noise MC Head Amp

This design was a development of Marshall Leach’s MC head-amp from the 1970’s and to my knowledge, Richard Lee’s implementation presented here has not been bested in terms of noise – about 280pV/rt Hz in a well implemented exemplar. Importantly, it requires only about 3-4mA of current in the +-15V rail powered version, and about a quarter of that in the battery version. If you try to achieve this type of performance with only NPN devices (the Diodes Inc ZTX851 being and excellent candidate), you will probably require 10 to 15 times the current, or an opamp and a lot more circuit complexity.

The design is not without its foibles in that it requires low rbb’ NPN-PNP complements, now (2019) difficult to get and the gain is directly dependent upon the cartridge DC resistance – so you have to select the output load resistor appropriately. Nevertheless, it is a fantastic example of the ‘less is more’ dictum and achieves remarkable performance for pennies.

Lee worked for various UK Hi-Fi outfits in the heyday of home audio in the 1960’s through 1980’s, including a stint at KEF, and is now retired to Cooktown, Queensland, Australia.