Hifisonix High Performance Balanced Line Stage

You can buy a stereo PCB for this line stage over in the Shop.

This OPA1641 and OPA1642 opamp based stereo line stage, which is used in the X-Altra Mini II full feature line level preamplifier, offers a balanced output for the left and right channels and 2 unbalanced outputs each for the left and right channels. As such, it can form the basis of a high performance line level preamplifier where the balanced outputs can be used, for example, to drive a power amplifier, one pair of unbalanced outputs to drive a sub bass leaving you with a spare set to perhaps drive a headphone amplifier. For level control, you can use an Alps RK16 or RK27 potentiometer, although on my original implementation, I used a beautiful Goldpoint 20k Log Taper level control. For build details and measurements, see the X-Altra Mini II presentation and for the BOM, see the X-Altra Mini II BOM (Excel) – sheet ‘Balanced Line Amp’.

Here are the specifications for the Balanced Line Stage

Here is a block diagram of the Balanced Line Stage


2 responses to “Hifisonix High Performance Balanced Line Stage”

  1. Bill Ellis says:

    Can the gain be reduced without compromising sound quality?

  2. admin says:

    Bill, on the balanced line stage, yes. The OPA1641/OPA1642 devices used are unity gain stable

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