Lately, I've been messing around with attenuators because at some gigs I was not able to get the right tone at the desired volume with my JTM45 clone and I wanted to do something about it. I came across a forum post on the marshall forums about reactive attenuators:
http://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/There are lots of information and experiments done, and there are two designs on the first page that are kind of stable. I built the smaller one cause I felt that I don't need the bypass switching and the resistive load options, and it's pretty simple. Volume is not really an issue anymore, I can even reduce the volume to bedroom level (though it does not sound good, cause the speakers are not really moving air how it supposed to). If you guys need lower volume, I think this is an easy build to do - thought some people would be interested in this here.
The -3.5dB step is missing from my build, I do not need that much switching options, so I omitted it from my build, you can easily do that too.
Schematics:
My build: