Check the listing for details. Professor Dan - Vacuum Tube Microphone Preamplifier and EQ. Color: Blue, Condition: New. Listed at 3500.00 USD. Professor Dan's original vacuum tube design. A boutique microphone preamplifier with no sonic compromises and the ability to shape your tone with a musical tube and inductor equalizer. You can even add dimension to your mixes with line level operation. Features 67 dB GainXLR Inputs/Outputs-25 dB PAD +48V Phantom Power Ø Polarity Switch High Pass FilterFixed Lo and Hi EQ bandsSelectable MID frequenciesMic and line level operation Carefully-Selected Components Cinemag transformers & inductorsV1 NOS General Electric 6072a tubesV2-V5 JJ 12AY7 and 12BH7 tubesWima film capacitors Elma and Grayhill Rotary SwitchesExternal power supply for low noise Specifications 20 Hz- 20 kHz (+/- 0.2 dB)8 Hz - 62 kHz (+/- 0.5 dB)-3dB @ 3 Hz and 85 kHzMax Output 28 dBu (1% distortion at 1 kHz into 600 ohm)Dim (3U): 19" W x 5.25" H x 11" D