This Magnatone (rebranded as Ariatone) 401 is an interesting amp. It doesn’t use a power transformer. The incoming line voltage is directly rectified, and the tube filaments run on the line AC. It uses a 20EZ7 tube for the preamp and tremolo, a 45B5/UL84 power tube (cathode biased), and a 36AM3A rectifier. There is a 1:3 transformer isolating the input jacks from the circuit. Also interesting is that the tremolo has no speed control, only depth.
In the interest of my customer’s safety, I have added a 1:1 isolation transformer on the incoming AC, and changed the cord to a grounded 3-wire.