Again, there are many ways to do this passive resistor load. A lot of these techniques, including the ones used by many commercially available load boxes, don’t maintain a constant impedance load to your amp as you change the attenuation. People debate whether this is important. You can search the net for these discussions. I decided I wanted to keep a constant impedance load to my amps.

By Sid of Stone Marmot

Warning: To keep this article a reasonable size, I purposely skipped listing all the safety steps I had taken while troubleshooting this amp. There are some very high and potentially lethal voltages and currents in these tube amps. If you are not intimately familiar with the safety precautions [...]