The pre-calibration modules are a set of four pairs of 100 ohm and 100k ohm precision (0.1% accurate) resistors mounted in four removeable modules that allows the owner of Tortuga Audio’ s LDR3x V2 & V2.1 Passive Preamp Controller Boards to perform a specific pre-calibration sequence to improve the overall accuracy of their preamps.
All Tortuga Audio LDR preamps sold starting January 1, 2015 have had this pre-calibration process performed as part of their commissioning. The only reason to repeat this process with a V2.1 controller board is if the user changes op amps.
Owners of existing V2 version of the LDR3x can improve their boards accuracy and performance by using a set of these pre-calibration modules.
More information of the pre-calibration process can be found here in our online documentation.