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Monday, November 18, 2013

Passive Transformer Volume Control Unit


Here some photos of a passive transformer volume control which I just finished.

Independent volume control switches for left and right channel. The two jacks on the left side are for headphones (both wired in parallel).

The unit uses Intactaudio AVCs (auto former volume control). Here a shot of the inside before it got mounted into the wooden enclosure:

All the wiring is done with teflon insulated solid core silver.

The backplate :

Just single sets of RCAs for  inputs and outputs.

The unit is similar to the passive line stage which I showed last year, except that it has no input selection switch but just a single stereo input.

Passive AVC units like this are meant for use with low impedance sources which are known to be able to cope well with the inductive load. Otherwise active line stages are my preferred solution.

Best regards



  1. hi thomas

    may i know how do you wire it for headphone usage?



  2. Hi!

    It will be used with headphones which are 300 Ohms impedance, So the headphone outputs are simply parallel to the RCA output