This microphone is inspired by and styled after the legendary "Neumann U-47", utilizing the German steel tube ( Stahlröhren) . We use a Telefunken Steel Tube in the 22 47 LE which works excellently in the circuit and provides the same sonic quality as the VF14. Each tube is selected individually and the selection parameters are the same or even better as Neumann used for the VF14. There are some tubes in the Telefunken Steel Tube family which are perfectly suitable to replace the old VF14 if they get an independent filament supply.
Technically the only difference in the tube used in the old U47 is that the one that we use has a separate filament supply coming from the power supply.
Our 22 47 LE has the additional feature of 9 polar patterns, controlled from the power supply. It captures the low frequency nuances of the original "47" with smooth mids and balanced highs.