Eli-Audio AMEK/TAC Scorpion Diff.004

Projects > Eli-Audio AMEK/TAC Scorpion Diff.004

Eli-Audio’s Diff.004 PCB is an API 2520 style Differential Line Receiver drop-in to replace the original pre-amp of the Amek/TAC Scorpion S1000/S1100 channel-strip. Eli designed this board to modify his own TAC Scorpion I console, and to improve the original “Bottle Neck” line-input of all 32 channels.

A discrete circuit, based on the 2520 design notes, was drawn around the well know 2520 DOA footprint, to accommodate the clean but dirty API sound, adding substantial grit to the audio signal! To install a Diff.004 line receiver in your channel-strip you need just remove some of the original parts on the main board, Eli’s PCB slides in place using existing solder pads, no wiring needed!!

There is a CMRR (Common mode Rejection Ratio) calibration option built in the design. For those not owning the right equipment for such calibrations, when using 0.1% resistors there’s no need for calibration, CMRR wil be excellent!

You can source your own parts and buy the PCB’s only, or get the full parts kit including all the surface mount components needed to build the sub-pcb. DOA’s (Discrete Operational Amplifiers) are not included in this kit!!

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  • Discrete differential line receiver.
  • Drop-in, no wiring!!
  • Takes any 2520 style DOA.
  • CMRR calibration with multi-turn trim pot or use 0.1% resistors for excellent results!


Boards and kit available at Eli’s store


  • PCB’s from €5.37/piece
  • Parts kit + PCB from €15/kit
  • No DOA’s included!

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3 thoughts on “Eli-Audio AMEK/TAC Scorpion Diff.004

  1. Hello, I’ll be very interested in ordering you two copies to get them on two slices of my TAC scorpion console.
    how can you pass command please in advance of your answer. Zoltan

  2. I would be interested in purchasing some of these. Is there a link somewhere that I am missing?

  3. I Would also like to buy several! is there any way to acquire these now? I cannot seem to find a working link

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