Klark Teknik DN27A- Mono 31 Band Graphic EQ
Just got Three of these in to overhaul. Nicely built units.
The owner had the original service manual and he was kind enough to send me photos of. The schematics available from KT online do not show the front end daughter board configuration...these do...
It has an interesting front end, no difference amp or transformer...One of the three units has a toroidal line output transformer, the other two just have RC high pass filter like shown in the above schematic.
Online I found versions with an input transformer as well. Interesting.
I have repaired/modified 12 units to date with almost that many manufacturing variations, but all the ones I worked on had a 110 to 220VAC switch installed