06-03-2017, 02:06 AM
No problem!
Linsley Hood also provided some insights in his 1969 modular pre-amplifier design, WW 1969 July p.306ff.
Therein, he basically used separate disc input amplifiers for the magnetic and ceramic cartridge cases, for the latter using a jfet input stage to provide a high (2M2) cartridge loading impedance. But he also showed how the magnetic cartridge input amplifier could be modified to provide both a high impedance and equalization for ceramic cartridges, the latter either to compensate for self-equalized cartridges that did not do a complete job, or for those few that had no in-built equalization. These thus required the full upstep of 12.5 dB between 500 and 2120 Hz, as shown in Linsley Hood’s graph.
In this case, the magnetic input amplifier was a three-transistor virtual earth circuit with shunt feedback, which Linsley Hood strongly favoured over the more common non-inverting series feedback type. This viewpoint resulted in the well-know debate with H.P. Walker in the letters pages of WW
WW 1972 May p.233ff: Walker article on low-noise amplifiers.
WW 1972 August p.389: (letters) Linsley Hood’s initial rejoinder.
WW 1972 November p.520: (letters) Walker’s response.
WW 1973 January pp.11,12: (letters) more from Linsley Hood.
WW 1973 April pp.193,194: (letters) Walker’s final comments (as far as I know).
Cheers,
Steve
Linsley Hood also provided some insights in his 1969 modular pre-amplifier design, WW 1969 July p.306ff.
Therein, he basically used separate disc input amplifiers for the magnetic and ceramic cartridge cases, for the latter using a jfet input stage to provide a high (2M2) cartridge loading impedance. But he also showed how the magnetic cartridge input amplifier could be modified to provide both a high impedance and equalization for ceramic cartridges, the latter either to compensate for self-equalized cartridges that did not do a complete job, or for those few that had no in-built equalization. These thus required the full upstep of 12.5 dB between 500 and 2120 Hz, as shown in Linsley Hood’s graph.
In this case, the magnetic input amplifier was a three-transistor virtual earth circuit with shunt feedback, which Linsley Hood strongly favoured over the more common non-inverting series feedback type. This viewpoint resulted in the well-know debate with H.P. Walker in the letters pages of WW
WW 1972 May p.233ff: Walker article on low-noise amplifiers.
WW 1972 August p.389: (letters) Linsley Hood’s initial rejoinder.
WW 1972 November p.520: (letters) Walker’s response.
WW 1973 January pp.11,12: (letters) more from Linsley Hood.
WW 1973 April pp.193,194: (letters) Walker’s final comments (as far as I know).
Cheers,
Steve
