Unbelievably the wizards at Retro Instruments have released a single-channel tube microphone preamp/line amp module that fits into a single slot of a 500 rack. Inside are three premium TAD 12AT7 tubes and CineMag input and output transformers.
The 500PRE has both high (75dB) and low gain (48dB) modes available using either two or three of its tube stages. Total 500 slot current drain is 160-mA and just over the allowable VPR spec.
The front panel has full size switches and control knobs for: Input Gain control, Low or High Gain Modes, 48-volt phantom power on/off, Invert off/on “flips” the polarity of the balanced mic input line, and the Output control sets final level.
I ran the 500PRE in an API 8P High Current 500 rack (250mA per slot) and..