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Purple Audio BIZ MK

Purple Audio BIZ MK
A unique sounding, three amplifier, discrete microphone preamp 500 Series module.

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€782.20 VAT Excluded

€782.20 VAT included
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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 one KDJ4 opamp.

Read a review from Tape Op Magazine!

Also be sure to check out the Purple Audio Pants Preamp!


  • 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


  • Maximum output level +27dBu
  • Frequency response 10hz – 70kHz +/- 1db (3db down at 100kHz)

Transformer input
Mic mode

  • Maximum gain 60dB in single mode
  • Maximum gain 75dB in dual mode

Line mode

  • Maximum gain 35dB in single mode
  • Maximum gain 50dB in dual mode

Direct input

  • Maximum gain 30dB in single mode
  • Maximum gain 40dB in dual mode

Beginning Serial Number 1600 February 2008

  • 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

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Product Details

Data sheet

500 Mic Pre
Solid State
Inout transformer(s)
Output transformer(s)
1 Slot
Purple Audio Biz MK Recall Sheet
Purple Audio Biz MK Recall Sheet
Download (75.6KB)
Overall rating
1 Review
Ease of use
Quality/price ratio
I just wanted to drop you a line to let you know how much I like the Biz module I purchased from you. Over the past two weeks I have been tracking a bunch of electric guitar (Les Paul and Marshall JCM-800) and we went through a pretty thorough comparison of quite a few different flavors of pre amp that I have in my set up. We put an AEA R-92 ribbon in front of an old Marshall 4X12 cab and went to town. The candidates were: API 312, API 512C, API 512A, Biz, OSA MP-L3, OSA MP-L, Chandler LTD-1, a pre from an E-Series SSL, and an old Ampex 351. All were great sounding in their own way, but both the player and I continually came back to the Biz and ended up using it for a majority of the tracks with some Chandler (for the 1073-esque flavor) and the 512C thrown in to add some different flavor. I found the Biz module to be big and thick – but not tubby. Aggressive – but not too edgy, and overall a very complimentary pre for the amp/guitar/mic combo we were using. I knew a product like this from you guys would be very good, but I have to say that the Biz is a stellar pre amp. I also intend to spread the word to my other 500-Series brothers
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