IO3 Relay Board


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The IO3 (input/output) Relay Board (the “IO3”) is a 1.7 inch x 2.5 inch circuit board that can be interfaced with the LDR3x Preamp Controller Board (versions 1 or 2) to enable switching between up to 3 audio input signals. In addition to its primary switching function, the IO3 also serves as an overall interface point between multiple input/output jacks and the LDR3x.

Input Switching

  • The IO3 switches between up to 3 singled-ended (unbalanced) audio inputs
  • For switching balanced audio, a pair of IO3 boards are required (each mated to its own LDR3x controller)
  • Switching is via individual non-latching electromechanical relays for each input/channel (3 per channel – 6 total)

Signal Separation

  • No co-mingling of left/right channel signals within the board
  • Allows for left and right channel ground to be kept separate

Power & Control 

  • Relays operate on 5 VDC with external power provided by the LDR3x Preamp Controller Board
  • Relays are activated by the LDR3x switching them to ground
  • Can be interfaced to any control device having similar “switch to ground” capability
  • Power & control are via  the following 4 signals connected to the 5 pin header
    • +5V
    • Input 1 (current sink to ground)
    • Input 2 (current sink to ground)
    • Input 3 (current sink to ground)


  • Termination via 0.1 inch (pitch) miniature screw terminal blocks
    • Between incoming audio signals and  the IO3 (2 x 6 position terminal blocks)
    • Between the IO3 and the LDR3x (2 x 3 position terminal blocks) – align with similar terminal blocks in LDR3x.V2 board
  • Alternative termination via solder pads for all input/output signals plus grounds
  • Board is same width (2.5 inches) as the LDR3x board (could be mounted on top of LDR3x with appropriates standoffs etc.).

More information on interfacing the IO3 with your audio inputs/outputs and the LDR3x can be found in our product documention here.

What’s Included? 

  • IO Board: 1.7 inch long by 2.5 inch wide (same width as LDR3x boards)
  • Power/Control Cable: A set of 4 female-female pin jumpers for connecting the IO Board to the LDR3x Preamp Controller Board

Please Note: Tortuga Audio does not provide any mounting fixtures or hardware.

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