I read through the 2Stroke parts list posted in the TAN WIKI. It specs the rectifier tube as a modern Sovtek 5Y3. The Sovtek 5Y3 delivers an output voltage similar to a solid state rectifier, producing a loud signal with punchy mids, tight bottom end and not much sag. A NOS 5Y3, like a Sylvania for example, gives a 35-45 volt reduction in rectifier output, resulting in a browner, greasier tone with more sag, more in the classic tweed era style. The 2nd 2Stroke I built includes a selectable rectifier (tube and SS) and it is easy to evaluate the tonal differences while measuring the voltages of different rectifier tubes compared to the SS circuit. BTW, the SS rectifier works great in the 2Stroke, I would not say it’s better or worse than the 5Y3 tube version, but it does offer a different tonal option. Also, it’s cheap (4 diodes cost: 25 cents) and very easy to build.