I got a start on my newest project: a single ended amp using a 6U8 triode/pentode for the preamp tube and a single ended 6V6 for the output.

Here are some pix.

The amp uses a 6U8 triode/pentode for the preamp. The pentode section is the input tube; the triode drives the 6V6. I have quite a few NOS 6U8 tubes as well as 6GH8 and 6BL8, which have the same pinout but slightly different ratings.

The output is based on the tweed Princeton/Champ. I decided to use JJ 6V6S tubes as I got a batch with the skinny pins. The ceramic tube sockets I got a while back grip the pins very tightly, which is good because the JJ 6V6S tubes are loose in the NOS sockets I have

One interesting thing about this circuit is that it has a built in compression control. More on that later.

I also plan on installing the VVR circuit using this layout. The VVR is a type of power scaling which uses a MosFet to control the anode voltages, and thereby reduce the ouput wattage. I've been wanting to try this for a while because it is supposed to give good OD sounds at whisper-quiet volumes. We'll see. The one bummer about using the VVR is that the MosFet costs about $12US. It really pains me to pay that much for a solid state device.

So far I've generated the schematic and the board layout. Next up is building the board, and then generating a chassis layout.

I've been wanting to do this project because eventually I want to build a push pull version of this amp using the 6U8, a 12AX7 phase inverter and a pair of 6V6 tubes. Maybe even a tube rectifier.

Stay tuned...

tung