Every now and then you just have to do something that doesn't make a lot of sense.
After all of the super linear circuits I have been working on lately I wanted to do something that was more about tone than anything else. I had a couple of EL84's and a 12AX7 handy so I jumped in and started building a tube amp for head phone listening.
My vacuum tube bread board adapters made it a snap! This design won't fit into my new modular console format so I will be putting it into a much larger chassis in the near future.
It's made up of a 12AX7 dual triode and a pair of EL84 pentode power tubes. Signal loss from the EL84 input to output is about 8db. So I decided to use the 12AX7 to make some gain. You can learn how to build your own 12AX7 gain stage by reading my design paper on my web page www.trentonblizzard.com . I use a Bourns dual conductive plastic pot as a volume control. Input impedance is basically determined by the pot and is around 50k.
I will be adding more detail to this post weekly. Stay tuned....