Bewag Pentode Dual Microphone Preamplifier

Built for Robbie Moore

Originally used by the Berliner Städtische Elektrizitätswerke or Bewag, here in Berlin as a high current power supply, I found this in a junk shop one day and thought it would make a great case for this project. Besides having a nice shape, the ergonomic handle really assists in the portability.

Design-wise, it is a very simple preamplifier. The Character control changes the EF86 from pentode to triode operation and everything in between. Essentially a gain control, this is especially useful when a bit of distortion or truly large amounts of gain are needed.From there, the Level control determines how much signal goes to the output tube-- a triode-strapped EL95-- which drives a balancing transformer.

Per usual, the preamp also accepts high impedance instrument and line inputs, as well as offering phantom power, phase and a -20dB pad.