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Friday, September 2, 2016

The 6J5 Line Preamplifier


Earlier this year I showed a version of my single chassis entry level line preamplifier with the 27 triode. Here is a variant of this with the 6J5.

They basically share the same circuit only with slight adaptions and parts selection for the tubes used.

The 27 preamp pretty much only has unity gain which is sufficient in most systems with sources with high output levels.

When some gain is needed, this version fits the bill with a bit over 12dB gain at full volume.

This particular unit has 3 inputs (more would be possible of course. It uses transformer volume controls like all my preamps. In this case Intactaudio units driven by Lundahl line output transformers.

The same arrangement on the top plate has been carried over from the 27 version. In this case also the same white color for the capacitors and transformer covers.

Gold color for the front and top plates as seen on the recent EC8020 phono stage. The wood is 'maple carbon effect' to match the stereo 300B amp with which it will be used.

Of course both  glass versions of the 6J5 can be used as well as metal versions:

View from the top:

A nice alternative if the 2 chassis versions of the line stage are too costly or the available space permits only a single chassis.

Best regards



  1. Very cool. I am thinking of building a 6J5 preamp for my brook 12a clones I will be starting soon. I'm torn between 112A and 6j5 preamp for the brook clone..

    Beautiful work as usual.

  2. Hi Thomas,

    Where does this preamp fit in your product line?
    Is it better than say, the 6AH4 line amp you use in your Octal preamp? (because the 6J5 is more linear than the 6AH4)

    Best regards,

    1. Hi!
      This represents the entry level now. I don't offer the Octal preamps any more.