This amplifier is my favorite SE valve design. It uses a 6L6 output tube, and a ECC83 for input. Again it was a test bed for lots of interesting ideas.

My first attempt at custom designed metal work!

Haven't quite finished the transition from rats nest to tag board yet.

As you can see, this amplifier is a hybrid!!! shock horror! In this amplifier I was interested in pushing the boundaries to see what could be achieved. The idea is to combine the good points of valves (high voltage) with transistors (high gain). A transistor is quite happy with a collector current of about 60 mA and sits nicely under the cathode of the 6L6. Running this amplifier open loop I could hear distortion , high output impedance, and that magical transparency, still there, not lost... In its final form, (for the time being) I got the distortion down to 0.02% at full output with 8dBs of feedback. The circuit has a rather odd arrangement of voltage rails and feedback because of the output cascode, which could probably be done better. It sounds very nice and clean in it low distortion form, but the feedback slightly mushes the sound. Well, it had to sound a bit like a valve amp... that was the whole point...