If i remember correctly they were the tubes in the eXstatA he designed without the helpful aid proffered by all the more knowleged personnel involved in that project.
That was before he decided to build the Liquid series of amps.
I still can't get over his decision to have a power supply for the eXstatA that was designed for newbie builders and that didn't have protection to stop the supply going unfunctional if it was powered up without a load.
I wonder how many supplies went west while their voltages were being dialed in when the load resistor went OC because the power rating was marginal, or was operated without a load.
The few extra components to make the supply able to stand without a load, or uprate the load resistor would have meant more builds in service.
The idea of making the build as cheap as possible for newbies was fraught with peril for the intended audience, and probably turned off budding DIYers in the process.