Quite interesting website Martin. Almost makes me want to learn German, but I fear my patience these days isn't what it used to be. For now I'll just look at the pictures

I have designed and build that in the old style, using solding stripes and wires binding.
As a experience. The plan what is where is the one and all, with the shortest possible connection. ( see Heathkit plans) The microphonic sensitive parts are the both microphone preamps, each with a EF86. The layout have a centered grounding at one point (negative out from PSU.). The most time is required for planing, the building is rather fast about the good plan.
Martin

What I used to do with German tape recorders like the Uher Stereo Record 3
was to add a new bridge rectifier fed from the transformer winding the for the magnets
needed to operate the record/play relays and the capstan seal-in.

That gave me 12 volts DC, to power the heaters of the EF86 tubes, and made a hum free
machine.

this morning i went back and looked all the pictures. very nice work Martin.
in 1979 i bought 2 sets of Canton speakers 1 pair of CT2000's and 1 pair of CT1000's 1 woofer in each is done and parts here are near impossible to find , but i am not giving up .
Cheers Don