Hairball Audio DIY-990 Opamp

Projects > Hairball Audio DIY-990 Opamp

Hairball Audio’s DIY-990 is a derivative of the JE-990 discrete operational amplifier. Since being designed by Deane Jensen in 1979 and released into the public domain, the 990’s many revisions have found their way into many high-quality audio designs such as the Jensen Twin Servo and Hairball Audio Lola preamps. The kit includes all the parts necessary for completion of a working DOA.

Hairball Audio DIY-990 Features:

  • Designed to the exact specifications found in Deane Jensen’s 1980 JE-990 AES paper
  • Comes with pre-soldered surface-mount transistor and bypass capacitors; through-hole components must be installed by the builder
  • Suited for use with 15/16V power supplies- R10 and R11 may be swapped with 62K resistors for operation with 24V power supplies
  • PCB designed by Mnats, made in the USA


  • $25 for DIY kit
  • $50 for assembled/tested unit

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