DISCLAIMER: Vacuum tube circuits work with dangerously high voltages. Do not attempt to build circuits presented on this site if you do not have the required experience and skills to work with such voltages. I assume no responsibility whatsoever for any damage caused by the usage of my circuits.

All rights of photos and text reserved. Usage of photos or text from my blog on other websites or for any other purpose only with prior permission. If you want to use any material from my blog please contact me by email.

Saturday, December 21, 2013

Making of a 801A / 211 Amplifier, Part 2: PSU Assembly


The first post about the creation of these 801A / 211 single ended mono block amplifiers showed how the layout was done. Part 2 will cover the assembly of the power supply chassis.

Everything starts with the top metal plate, here with connectors, sockets and switch mounted:

The bottom side:

While the filament transformer for the driver tube will be mounted on top of the plate, the other transformers are too high to fit under the cover. They need to be mounted slightly lower. Here a foto with the power transformers mounted:

View from below, which shows how the two larger transformers are mounted on rails:

Some foots showing details how the transformers are mounted below the plate:

Wiring of the transformers:

Adding the filament supply section:

Almost finished PSU with capacitors and chokes added for output and driver section high voltage supplies. The green resistors are only temporarily added for testing, and will later be replaced by aluminium cased resistors.

Testing the power supply:

One of the power supplies finished with final bleeder resistors. Ready for the transformer covers to be added and to be encased into the wooden frame.

The assembly of the amplifier chassis will be shown next. Stay tuned!

Best regards



  1. Hi Thomas,
    I see you connect PE to both the filament and plate voltage connector. May I ask for your reasons to connect it through both umbilicals? For shielding?


    1. Hi Daniel,

      well observed :-)
      I wanted to make sure PE is always connected even if the user accidentally has only one of the umbilicals attached and switches the PSU on.

      Best regards