Purple Audio Biz MK 500 Series Mic Preamp


500 Series Discrete Microphone Preamplifier

Manufacturer Description:

A unique sounding, three amplifier, discrete microphone preamp module designed to work in standard “500″ racks.

The smooth Gain control helps you dial in the sound you want. If the output level is too high (the Class A/B output opamp can pump out up to +27 dBu), you can ride the level down with the separate Level control.

Pressing the “Dual” switch splits the gain between two of our Class A opamps, enabling up to 75 dBu of clean gain, making the Biz a perfect match for ribbon microphones.

With different Gain, Level, and Dual settings the Biz can produce an infinite variety of tonal variations with the same amount of output level. The front panel DI helps you record instruments and line level sources with unrivaled clarity and punch.

Two LEDs clearly indicate signal level for the gain and output stages at a glance, turning green to indicate signal present, yellow for 10dB below clipping, and red for clipping. The Biz uses two KDJ3 opamps and oneKDJ4 opamp.


  • Output level control
  • Input and output tricolor LED metering
  • Mic / Line switch for rack input Bridging line input for high output mics or line level sources Use with our Moiyn 8×2 mixer module in the Sweet Ten rack for mic or line mixing
  • DI Load switch for front panel input 33kohms as in the original Biz or 100kohms for a more open tone
  • Discrete signal path
  • Over Current Resettable Fused (prevents any module problem from affecting your rack)
  • ROHS – Lead Free


Biz Pinout:

  • Pin 1: Chassis Ground
  • Pin 2: Output A +
  • Pin 3: Output B+ (Purple Audio Rack Only – XLR OUT 2)
  • Pin 4: Output A -
  • Pin 5: Audio Ground
  • Pin 6: Output B – (Purple Audio Rack Only – XLR OUT 2)
  • Pin 7: Input -
  • Pin 8: Input -
  • Pin 9: Input +
  • Pin 10: Input +
  • Pin 11: NC
  • Pin 12: +15 or 16VDC 80ma
  • Pin 13: Audio Ground
  • Pin 14: -15 or 16VDC 80ma
  • Pin 15: +48VDC

Year Condition
Call Brand New


Sound Pure
Durham, NC
4:24 PM
10am-6pm EST Monday-Friday and 11am-5pm Saturday