K&K Phono Preamp questions.

@lewm ,

I don’t think the OP gave us a mirror example of how his phono looks. The link showed a blank front plate with no company logo or the switching options he talked about.

That picture leads me to believe it may have been a customer built kit?

I had just assumed the polarity switch on my Trio was regarding the music signal, not the AC polarity.

Since it appears you have the oldest version of the K&K, I'm guessing it will use two 6N1P Russian tubes.  Any of the newer PCB based units will use two 6N23P tubes.  I've tried swapping nearly every known variant of the the equivalent 6922/E88CC/7308 etc, and I always come back to the Russian tubes.  Kevin designed the unit around that tube, and it sounds best with them IMO.

palasr 

Thanks for the feedback. The Russian Tubes have been entered into the notepad for future reference. 

Looking at the photos of other K&K phono stages, it appears the design changed to a single circuit board rather than multiple boards. 

This unit has a pair of Cardas Golden ratio 4.7uf capacitors. It appears as though many units used different types as well as combinations of capacitors in this position. 

If the polarity switch is on the rear panel next to the IEC input for the AC cord, then I might imagine it is for input AC polarity. However, it is also true that the balanced circuit in at least many of the K&K phono stages permits switching the polarity of the audio signal. Like you, I would expect the switch for audio signal polarity to be on the front panel for easy access.