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818.437.0779Email Danny "Sage" McKinney

OS1 Preamplifier MK II

- Starting at $3,500 -

Microphone Preamplifier

The OS1 was developed around the 6SN7 vacuum tube. The 6SN7 was developed in 1939 and, over the years, has become my personal favorite and often considered king of the general-purpose audio triodes. High headroom and broad frequency response are the hallmarks of the OS1. The OS1 can drive a 600-ohm load at a +40dB output and has an internal frequency response of 10Hz to 600,000Hz. This is a very special microphone preamplifier, designed especially for the most demanding audio professional.

Technical Details


  • Variable Microphone Impedance - Six Positions
  • Hi-Pass Filter - Four Positions
  • Mic/DI Gain - Infinitely Variable
  • Meter Range - Three Positions
  • DI Input
  • 20dB Pad
  • Phantom Power
  • Polarity Reverse
  • Extra Large VU Meter


  • Power Supply Inlet (choice of Tube or Solid-State Supply)
  • Transformer Balanced XLR Output (pin 2 HI)
  • Tube Channel (6SN7 - shock mounted - 3 each)
  • Transformer Balanced XLR Input (pin 2 HI)


  • Solid-Core Copper/Silver Wire with Teflon Dielectric
  • Handwired, Point-To-Point Throughout (only Meter/Phantom on PCB)
  • Custom Input and Output Transformers
  • Audio Circuit Shock Mounted
  • Overbuilt - using highly rated, quality components

Special Features

Select a Power Supply


Upgrade to the absolute best OS1 components

  1. Standard Components $0
  2. Super FI Components $2,600