Spot on, yes Tannoy's bought the brains as well as the documentation et al.
about 7 years ago, I came across a DR-1 Tresham pre amp, with no power supply...1st call = Tannoy. I spoke to customer services; Can't help you Sir point blank.
2nd Call to Schweppes (You know who): totally negative response, didn't want to know, why don't you try one of my plastic boxes with earthing problems?
There's load more, but this thread is all about re creating a power supply, and whose got the schematics...