Beyer M55 microphone with Pleiades preamplifier connected to EMI RS61

Setup, signal path:


Male singing voice at 1 in - Beyer M55 - 500Ω to 50KΩ transformer with 300mH primary inductance - Pleiades V series ECC82 12 volt pre preamplifier - EMI RS61 - EMI RS106A - Sennheiser HD580


Possibly the best quality sound ever heared.


The Beyer M55 gives an almost flat frequency responce from singer's vocal chords to listener's brain. So EQing was not needed.


It's 500Ω impedance is stepped up to 50KΩ by the external 1/4in to 1/4in signal transformer.


The signal goes through a 10nF coupling capacitor to the grid of ECC82. The cathode is connected to battery (-) or ground. This pre preamplifier operates with only 12V from a small lead acid battery for both heaters and anode. This is made possible by a 10MΩ resistor from anode to grid to free the electrons from the cathode electron cloud. The anode is directly connected to a military output transformer. The other side it's primary to 12V. The secondary gets us back to low impedance. So with a circuit quite simple and similar to the Neumann U47 we have a very low noise and strong signal of low impedance. So we have similar conditions to a top condencer microphone by a world class moving coil microphone. The noise is so low and a reason may be that at such low potentials any secondary electron emission effect is almost eliminated.


The RS61 input is then driven in a similar way to when it was driven by the VF14 tube amplifier of the Neumann U47.


Firstly the 300Ω headphones were connected directly to the RS61. It was an amazing full dynamic and clean sound.


To avoid high pressure levels at ears the RS106A was connected to flat responce and its 200Ω to 200Ω variable attenuator used.


Possibly the best.