Thanks for the welcome.
I'm not good at writing up projects, but I wrote up a couple of small ones on
http://www.desmith.net/NMdS/Electronics - the Quad 405-2 rebuild is there and some other small stuff.
Most of the rest is in forum posts on AT or elsewhere - many other projects around the web - mostly HV stuff to do with solid-state Tesla coils & EM can-crushers etc.
Currently I'm working on an ultra-low-noise heater supply - there's a lot of tech in it and hopefully it'll sound good too - specs are 2-20V @ up to 10A, ideal bridge, SMPS pre-regulator, ultra-low-noise linear secondary regulator, current sourced (Hi-Z) floating output (can be biased +/- 1kV), programmable slow start and shutdown, opto-isolated power-good out and power on/off input.
Because of the use of the ideal bridge and pre-regulator, efficiency should be very high (c. 90%) and power dissipation very low - one of my pet hates with DHT and other purely linear supplies is the huge heat output, coupled with switching noise from the bridge and transformer ringing etc. (although that can be mitigated with suitable snubbing) - this is all well documented by Morgan Jones and others in Linear Audio and elsewhere. There are some cool features too, like true linear current increase during soft-start, not the usual simple RC model - much kinder on a cold filament...
Another advantage of an SMPS regulator is that I may make it a buck/boost, i.e. it could be possible to use a lower voltage xfrmr winding to drive a higher voltage heater... buck/boost is a more complex configuration requiring more real estate and adds to what is an already complex project - this is a nice to have, not must have.
There are a lot of engineering issues to work through, specifically with managing any EMI (not that big a deal), but I have a bunch of 6C33Cs and 13E1s etc. that need a good, compact, efficient heater supply... The prototypes are looking and sounding good but there is a bunch of work still to do.
As I'm mostly out of the UK and away from my workshops now, it's unlikely I'll have boards for others before the year end, but I'm always hopeful