The Wattkins Universal PCB is one of the basic building blocks for building a guitar amplifier with up to four vacuum tubes. It supports most amp designs (it started out life as a Fender 5E3 Tweed Deluxe), including support for Paraphase, Cathodyne and Long Tail Pair phase inverter as well as Cathode or Fixed Bias. As well as the more common 12AX7 & EF86 pre-amp tubes, it also supports Russian pre-amp tubes such as 6N2P & 6J32P with the heaters on pins 4 & 5. Output tubes supported include 6V6, 6L6 and 5881.
This is Dave Brons and his homebrew guitar amp. It's a low cost ThriftyWreck design, which is based around Ken Fisher's Trainwreck design, but uses alternative Russian tubes such as the 6p1p. Find out more from Wattkins Amp Forums' Tone Per Buck Club.